Related References

Author: Tokutsu, R.; Teramoto, H.; Takahashi, Y.; Ono, T. A.; Minagawa, J.
Year: 2004
Title: The light-harvesting complex of photosystem I in Chlamydomonas reinhardtii: protein composition, gene structures and phylogenic implications
Journal: Plant Cell Physiol
Volume: 45
Issue: 2
Pages: 138-145
Date: Feb
Abstract: Light-harvesting chlorophyll a/b-binding proteins (LHCI) associated with photosystem I (PSI) and the genes encoding these proteins have been characterized in the unicellular green alga Chlamydomonas reinhardtii, extending previous studies of the PSII-LHCII [Teramoto et al. (2001) Plant Cell Physiol. 42: 849]. In order to assign LHCI proteins in the thylakoid membranes, the PSI-LHCI supercomplex that retains all of the major LHCI proteins was purified. Seven distinct LHCI proteins were resolved from the purified supercomplex by a high-resolution SDS polyacrylamide gel electrophoresis, and their N-terminal amino acid sequences were determined. One LHCI protein (band e) was newly found, although the other six LHCI proteins corresponded to those previously reported. Genomic clones encoding these seven LHCI proteins were newly isolated and the nucleotide sequences were determined. A comprehensive characterization of all members of Lhc gene family in this alga revealed that LHCI proteins are more highly diverged than LHCII, suggesting functional differentiation of the protein components in LHCI. Neighbor joining trees were constructed for LHC proteins from C. reinhardtii and those of Arabidopsis thaliana or Galdieria sulphuraria to assess evolutionary relationships. Phylogenetic analysis revealed that (1). green algal LHCI and LHCII proteins are more closely related to one another than to LHCI proteins in red algae, (2). green algae and higher plants possess seven common lineages of LHC proteins, and (3). Type I and III LHCI proteins are conserved between green algae and higher plants, while Type II and IV are not. These findings are discussed in the context of evolution of multiple diverse antenna complexes.

Author: Nagasaka, S.; Nishizawa, N. K.; Mori, S.; Yoshimura, E. Y.
Year: 2004
Title: Metal metabolism in the red alga Cyanidium caldarium and its relationship to metal tolerance
Journal: Biometals
Volume: 17
Issue: 2
Pages: 177-181
Date: Apr
Abstract: The unicellular red alga Cyanidium caldarium is tolerant to high levels of various metal ions. Cells of this alga cultured with divalent metal ions at 5 mM contained an elevated concentration of each metal, with the highest level for Zn followed by Mn > Ni > Cu. This order is in fair agreement with the toxicity levels reported previously, with the exception of Mn, which shows a toxicity level comparable to that of Ni. Transmission electron microscopy indicated the presence of electron-dense bodies in the algal cells, and elemental analysis by energy dispersive X-ray spectrometry showed high levels of Fe and P in these bodies. Accumulation of Zn was found in these particles in Zn-treated algal cells, whereas no such deposition was found for Cu, Ni, or Mn in cells treated with the respective metals. Although trapping of Zn in the intracellular bodies may contribute to reduction of metal activity in the cells, this effect can be overcome by high intracellular levels of Zn that result in a high degree of toxicity. The correlation between intracellular concentration and toxic levels of metal ions implies that the reduced incorporation of the metals is a major detoxification mechanism in this alga.

Author: Miyagishima, S. Y.; Nozaki, H.; Nishida, K.; Matsuzaki, M.; Kuroiwa, T.
Year: 2004
Title: Two types of FtsZ proteins in mitochondria and red-lineage chloroplasts: the duplication of FtsZ is implicated in endosymbiosis
Journal: J Mol Evol
Volume: 58
Issue: 3
Pages: 291-303
Date: Mar
Abstract: The ancestors of plastids and mitochondria were once free-living bacteria that became organelles as a result of endosymbiosis. According to this theory, a key bacterial division protein, FtsZ, plays a role in plastid division in algae and plants as well as in mitochondrial division in lower eukaryotes. Recent studies have shown that organelle division is a process that combines features derived from the bacterial division system with features contributed by host eukaryotic cells. Two nonredundant versions of FtsZ, FtsZ1 and FtsZ2, have been identified in green-lineage plastids, whereas most bacteria have a single ftsZ gene. To examine whether there is also more than one type of FtsZ in red-lineage chloroplasts (red algal chloroplasts and chloroplasts that originated from the secondary endosymbiosis of red algae) and in mitochondria, we obtained FtsZ sequences from the complete sequence of the primitive red alga Cyanidioschyzon merolae and the draft sequence of the stramenopile (heterokont) Thalassiosira pseudonana. Phylogenetic analyses that included known FtsZ proteins identified two types of chloroplast FtsZ in red algae (FtsZA and FtsZB) and stramenopiles (FtsZA and FtsZC). These analyses also showed that FtsZB emerged after the red and green lineages diverged, while FtsZC arose by the duplication of an ftsZA gene that in turn descended from a red alga engulfed by the ancestor of stramenopiles. A comparison of the predicted proteins showed that like bacterial FtsZ and green-lineage FtsZ2, FtsZA has a short conserved C-termmal sequence (the C-terminal core domain), whereas FtsZB and FtsZC, like the green-lineage FtsZ1, lack this sequence. In addition, the Cyanidioschyzon and Dictyostelium genomes encode two types of mitochondrial FtsZ proteins, one of which lacks the C-terminal variable domain. These results suggest that the acquisition of an additional FtsZ protein with a modified C terminus was common to the primary and secondary endosymbioses that produced plastids and that this also occurred during the establishment of mitochondria, presumably to regulate the multiplication of these organelles.

Author: Matsuzaki, M.; Misumi, O.; Shin, I. T.; Maruyama, S.; Takahara, M.; Miyagishima, S. Y.; Mori, T.; Nishida, K.; Yagisawa, F.; Yoshida, Y.; Nishimura, Y.; Nakao, S.; Kobayashi, T.; Momoyama, Y.; Higashiyama, T.; Minoda, A.; Sano, M.; Nomoto, H.; Oishi, K.; Hayashi, H.; Ohta, F.; Nishizaka, S.; Haga, S.; Miura, S.; Morishita, T.; Kabeya, Y.; Terasawa, K.; Suzuki, Y.; Ishii, Y.; Asakawa, S.; Takano, H.; Ohta, N.; Kuroiwa, H.; Tanaka, K.; Shimizu, N.; Sugano, S.; Sato, N.; Nozaki, H.; Ogasawara, N.; Kohara, Y.; Kuroiwa, T.
Year: 2004
Title: Genome sequence of the ultrasmall unicellular red alga Cyanidioschyzon merolae 10D
Journal: Nature
Volume: 428
Issue: 6983
Pages: 653-657
Date: Apr 8
Abstract: Small, compact genomes of ultrasmall unicellular algae provide information on the basic and essential genes that support the lives of photosynthetic eukaryotes, including higher plants. Here we report the 16,520,305-base-pair sequence of the 20 chromosomes of the unicellular red alga Cyanidioschyzon merolae 10D as the first complete algal genome. We identified 5,331 genes in total, of which at least 86.3% were expressed. Unique characteristics of this genomic structure include: a lack of introns in all but 26 genes; only three copies of ribosomal DNA units that maintain the nucleolus; and two dynamin genes that are involved only in the division of mitochondria and plastids. The conserved mosaic origin of Calvin cycle enzymes in this red alga and in green plants supports the hypothesis of the existence of single primary plastid endosymbiosis. The lack of a myosin gene, in addition to the unexpressed actin gene, suggests a simpler system of cytokinesis. These results indicate that the C. merolae genome provides a model system with a simple gene composition for studying the origin, evolution and fundamental mechanisms of eukaryotic cells.

Author: Yoshida, E.; Nakamura, A.; Watanabe, T.
Year: 2003
Title: Reversed-phase HPLC determination of chlorophyll a' and naphthoquinones in photosystem I of red algae: existence of two menaquinone-4 molecules in photosystem I of Cyanidium caldarium
Journal: Anal Sci
Volume: 19
Issue: 7
Pages: 1001-1005
Date: Jul
Abstract: Chlorophyll (Chl) a', the C13(2)-epimer of Chl a, is one of the two Chl molecules constituting the primary electron donor (P700) of photosystem (PS) I of a thermophilic cyanobacterium Synechococcus elongatus. To examine whether PS I of other oxygenic photosynthetic organisms in general contain one Chl a' molecule in P700, the pigment composition of thylakoid membranes and PS I preparations isolated from red algae Porphyridium purpureum and Cyanidium caldarium was examined by reversed-phase HPLC with particular attention to Chl a' and phylloquinone (PhQ), the secondary electron acceptor of PS I. The two red algae contained one Chl a' molecule at the core part of PS I. In PS I of C. caldarium, two menaquinone-4 (MQ-4) molecules were detected in place of PhQ used by higher plants and cyanobacteria. The 1:2:1 stoichiometry among Chl a', PhQ (MQ-4) and P700 in PS I of the red algae indicates that one Chl a' molecule universally exists in PS I of oxygenic photosynthetic organisms, and two MQ-4 molecules are associated with PS I of C. caldarium.

Author: Suzuki, T.; Minagawa, J.; Tomo, T.; Sonoike, K.; Ohta, H.; Enami, I.
Year: 2003
Title: Binding and functional properties of the extrinsic proteins in oxygen-evolving photosystem II particle from a green alga, Chlamydomonas reinhardtii having His-tagged CP47
Journal: Plant Cell Physiol
Volume: 44
Issue: 1
Pages: 76-84
Date: Jan
Abstract: Oxygen-evolving photosystem 11 (PSII) particles were purified from Chlamydomonas reinhardtii having His-tag extension at the C terminus of the CP47 protein, by a single-step Ni2(+)- affinity column chromatography after solubilization of thylakoid membranes with sucrose monolaurate. The PSII particles consisted of, in addition to intrinsic proteins, three extrinsic proteins of 33, 23 and 17 kDa. The preparation showed a high oxygen-evolving activity of 2,300-2,500 mumol O-2 (mg Chl)(-1) h(-1) in the presence of Ca2+ using ferricyanide as the electron acceptor, while its activity was 680-720 mumol O-2 (mg Chl)(-1) h(-1) in the absence of Ca2+ and Cl- ions. The activity was 710-820 mumol O-2 (mg Chl)(-1) h(-1) independent of the presence or absence of Ca2+ and Cl when 2,6-dichloro-p- benzoquinone was used as the acceptor. These activities were scarcely inhibited by DCMU. The kinetics of flash-induced fluorescence decay revealed that the electron transfer from Q(A)(-) to Q(B), was significantly inhibited, and the electron transfer from Q(A)(-) to ferricyanide was largely stimulated in the presence of Ca2+. These results indicate that the acceptor side, Q(B) site, was altered in the PSII particles but its donor side remained intact. Release-reconstitution experiments revealed that the extrinsic 23 and 17 kDa proteins were released only partially by NaCl-wash, while most of the three extrinsic proteins were removed when treated with urea/NaCl, alkaline Tris or CaCl2- The 23 and 17 kDa proteins directly bound to PSII independent of the other extrinsic proteins, and the 33 kDa protein functionally re-bound to CaCl2-treated PSII which had been reconstituted with the 23 and 17 kDa proteins. These binding properties were largely different from those of the extrinsic proteins in higher plant PSII, and suggest that each of the three extrinsic proteins has their own binding sites independent of the others in the green algal PSII.
ISI:000180841900011

Author: Reichert, A.; Dennes, A.; Vetter, S.; Scheibe, R.
Year: 2003
Title: Chloroplast fructose 1,6-bisphosphatase with changed redox modulation: comparison of the Galdieria enzyme with cysteine mutants from spinach
Journal: BBA-Proteins Proteomics
Volume: 1645
Issue: 2
Pages: 212-217
Date: Feb 21
Abstract: Spinach fructose 1,6-bisphosphatase (FBPase, EC 3.1.3.11), a redox-modulated chloroplast enzyme and part of the Calvin cycle, and three different Cys mutants were expressed in E. coli. The properties of the purified proteins were compared to those of native and recombinant chloroplast FBPase from the red alga Galdieria sulphuraria. In spinach chloroplast FBPase, Cys(155) and Cys(174) are engaged in the formation of the disulfide bridge. The corresponding mutants are active when expressed in E. coli, while C179S is inactive and can be reductively activated as can the wild-type enzyme. The active C174S mutant, however, could be inactivated by oxidation, and reactivated, but only by reduction, not alternatively with high pH and high Mg2+ as is the case for the wild-type enzyme. In the sequence of Galdieria FBPase, the Cys that corresponds to Cys(179) in the spinach enzyme is lacking. However, the Galdieria FBPase, in contrast to the spinach Cys(179) mutant, does not show any indication for a comparable redox modulation of its activity. Instead, oxidation only leads to partial inactivation without any qualitative changes in enzyme properties. Upon reduction, the lost activity can be recovered. © 2002 Elsevier Science B.V. All rights reserved.
Go to ISI:000180957900012

Author: Ohta, N.; Matsuzaki, M.; Misumi, O.; Miyagishima, S. Y.; Nozaki, H.; Tanaka, K.; Shin, I. T.; Kohara, Y.; Kuroiwa, T.
Year: 2003
Title: Complete sequence and analysis of the plastid genome of the unicellular red alga Cyanidioschyzon merolae
Journal: DNA Res
Volume: 10
Issue: 2
Pages: 67-77
Date: Apr 30
Abstract: The complete nucleotide sequence of the plastid genome of the unicellular primitive red alga Cyanidioschyzon merolae 10D (Cyanidiophyceae) was determined. The genome is a circular DNA composed of 149,987 bp with no inverted repeats. The G + C content of this plastid genome is 37.6%. The C. merolae plastid genome contains 243 genes, which are distributed on both strands and consist of 36 RNA genes (3 rRNAs, 31 tRNAs, tmRNA, and a ribonuclease P RNA component) and 207 protein genes, including unidentified open reading frames. The striking feature of this genome is the high degree of gene compaction; it has very short intergenic distances (approximately 40% of the protein genes were overlapped) and no genes have introns. This genome encodes several genes that are rarely found in other plastid genomes. A gene encoding a subunit of sulfate transporter (cysW) is the first to be identified in a plastid genome. The cysT and cysW genes are located in the C. merolae plastid genome in series, and they probably function together with other nuclear-encoded components of the sulfate transport system. Our phylogenetic results suggest that the Cyanidiophyceae, including C. merolae, are a basal clade within the red lineage plastids.

Author: Nozaki, H.; Matsuzaki, M.; Takahara, M.; Misumi, O.; Kuroiwa, H.; Hasegawa, M.; Shin-i, T.; Kohara, Y.; Ogasawara, N.; Kuroiwa, T.
Year: 2003
Title: The phylogenetic position of red algae revealed by multiple nuclear genes from mitochondria-containing eukaryotes and an alternative hypothesis on the origin of plastids
Journal: J Mol Evol
Volume: 56
Issue: 4
Pages: 485-497
Date: Apr
Abstract: Red algae are one of the main photosynthetic eukaryotic lineages and are characterized by primitive features, such as a lack of flagella and the presence of phycobiliproteins in the chloroplast. Recent molecular phylogenetic studies using nuclear gene sequences suggest two conflicting hypotheses (monophyly versus non-monophyly) regarding the relationships between red algae and green plants. Although kingdom-level phylogenetic analyses using multiple nuclear genes from a wide-range of eukaryotic lineages were very recently carried out, they used highly divergent gene sequences of the cryptomonad nucleomorph (as the red algal taxon) or incomplete red algal gene sequences. In addition, previous eukaryotic phylogenies based on nuclear genes generally included very distant archaebacterial sequences (designated as the outgroup) and/or amitochondrial organisms, which may carry unusual gene substitutions due to parasitism or the absence of mitochondria. Here, we carried out phylogenetic analyses of various lineages of mitochondria-containing eukaryotic organisms using nuclear multigene sequences, including the complete sequences from the primitive red alga Cyanidioschyzon merolae. Amino acid sequence data for two concatenated paralogous genes (alpha- and beta-tubulin) from mitochondria-containing organisms robustly resolved the basal position of the cellular slime molds, which were designated as the outgroup in our phylogenetic analyses. Phylogenetic analyses of 53 operational taxonomic units (OTUs) based on a 1525-amino-acid sequence of four concatenated nuclear genes (actin, elongation factor-1alpha, alpha-tubulin, and beta-tubulin) reliably resolved the phylogeny only in the maximum parsimonious (MP) analysis, which indicated the presence of two large robust monophyletic groups (Groups A and B) and the basal eukaryotic lineages (red algae, true slime molds, and amoebae). Group A corresponded to the Opisthokonta (Metazoa and Fungi), whereas Group B included various primary and secondary plastid-containing lineages (green plants, glaucophytes, euglenoids, heterokonts, and apicomplexans), Ciliophora, Kinetoplastida, and Heterolobosea. The red algae represented the sister lineage to Group B. Using 34 OTUs for which essentially the entire amino acid sequences of the four genes are known, MP, distance, quartet puzzling, and two types of maximum likelihood (ML) calculations all robustly resolved the monophyly of Group B, as well as the basal position of red algae within eukaryotic organisms. In addition, phylogenetic analyses of a concatenated 4639-amino-acid sequence for 12 nuclear genes (excluding the EF-2 gene) of 12 mitochondria-containing OTUs (including C. merolae) resolved a robust non-sister relationship between green plants and red algae within a robust monophyletic group composed of red algae and the eukaryotic organisms belonging to Group B. A new scenario for the origin and evolution of plastids is suggested, based on the basal phylogenetic position of the red algae within the large clade (Group B plus red algae). The primary plastid endosymbiosis likely occurred once in the common ancestor of this large clade, and the primary plastids were subsequently lost in the ancestor(s) of the Discicristata (euglenoids, Kinetoplastida, and Heterolobosea), Heterokontophyta, and Alveolata (apicomplexans and Ciliophora). In addition, a new concept of "Plantae" is proposed for phototrophic and nonphototrophic organisms belonging to Group B and red algae, on the basis of the common history of the primary plastid endosymbiosis. The Plantae include primary plastid-containing phototrophs and nonphototrophic eukaryotes that possibly contain genes of cyanobacterial origin acquired in the primary endosymbiosis.

Author: Nagasaka, S.; Nishizawa, N. K.; Watanabe, T.; Mori, S.; Yoshimura, E.
Year: 2003
Title: Evidence that electron-dense bodies in Cyanidium caldarium have an iron-storage role
Journal: Biometals
Volume: 16
Issue: 3
Pages: 465-470
Date: Sep
Abstract: The acidophilic and thermophilic unicellular red alga, Cyanidium caldarium (Tilden) Geitler, is widely distributed in acidic hot springs. Observation by transmission electron microscopy (TEM) showed that algae grown in Allen's medium contained electron-dense bodies with diameters from 100 to 200 nm. Electron dispersive x-ray analysis indicated that the electron-dense bodies contained high levels of iron, phosphorous, and oxygen; P/Fe ratios were from 1.3 to 2.0. The electron spin resonance (ESR) spectrum of the intact C. caldarium cells showed an isotropic signal at a g value of 2.00. Density-gradient centrifugation of the cell lysate yielded a fraction that included substances showing the isotropic ESR signal. EDTA treatment of this fraction reduced the ESR signal intensity, whereas it increased a signal that is typical of Fe(III)-EDTA. The fact that the isotropic signal dominates the ESR spectrum, together with a previous finding that iron is confined to the electron-dense bodies, led us to conclude that iron in the electron-dense bodies accounts for the isotropic ESR signal. Since the intensity of the ESR signal depends on the amount of iron in the cells, the electron-dense bodies are probably iron storage sites.

Author: Miyagishima, S. Y.; Nishida, K.; Mori, T.; Matsuzaki, M.; Higashiyama, T.; Kuroiwa, H.; Kuroiwa, T.
Year: 2003
Title: A plant-specific dynamin-related protein forms a ring at the chloroplast division site
Journal: Plant Cell
Volume: 15
Issue: 3
Pages: 655-665
Date: Mar
Abstract: Chloroplasts have retained the bacterial FtsZ for division, whereas mitochondria lack FtsZ except in some lower eukaryotes. Instead, mitochondrial division involves a dynamin-related protein, suggesting that chloroplasts retained the bacterial division system, whereas a dynamin-based system replaced the bacterial system in mitochondria during evolution. In this study, we identified a novel plant-specific group of dynamins from the primitive red alga Cyanidioschyzon merolae. Synchronization of chloroplast division and immunoblot analyses showed that the protein (CmDnm2) associates with the chloroplast only during division. Immunocytochemical analyses showed that CmDnm2 appears in cytoplasmic patches just before chloroplast division and is recruited to the cytosolic side of the chloroplast division site to form a ring in the late stage of division. The ring constricts until division is complete, after which it disappears. These results show that a dynamin-related protein also participates in chloroplast division and that its behavior differs from that of FtsZ and plastid-dividing rings that form before constriction at the site of division. Combined with the results of a recent study of mitochondrial division in Cyanidioschyzon, our findings led us to hypothesize that when first established in lower eukaryotes, mitochondria and chloroplasts divided using a very similar system that included the FtsZ ring, the plastid-dividing/mitochondrion-dividing ring, and the dynamin ring.

Author: Linka, N.; Hurka, H.; Lang, B. F.; Burger, G.; Winkler, H. H.; Stamme, C.; Urbany, C.; Seil, I.; Kusch, J.; Neuhaus, H. E.
Year: 2003
Title: Phylogenetic relationships of non-mitochondrial nucleotide transport proteins in bacteria and eukaryotes
Journal: Gene
Volume: 306
Pages: 27-35
Date: Mar 13
Abstract: Current knowledge about the nucleotide metabolism of intracellular bacteria is very limited. Here we report on the identification of nucleotide transport proteins (NTT) of two obligate endoparasites, Caedibacter caryophila and Holospora obtusa, both alpha-proteobacteria, which reside in the vegetative macronucleus of Paramecium caudatum. For comparative studies, we also identified the first nucleotide transporter in chloroplasts of a red alga, i.e. Galdieria sulphuraria, and further homologs in plant chloroplasts. Heterologous expression of the NTT proteins from C. caryophila, H. obtusa, and G. sulphuraria in Escherichia coli demonstrate that the nucleotide influx mediated by these transporters is specific for ATP and ADP. The NTT proteins of C. caryophila and H. obtusa exhibit substantial sequence identity with their counterparts in chloroplasts and intracellular bacterial pathogens of humans, but not with the nucleotide transport system of mitochondria. Comprehensive phylogenetic analyses of bacterial and chloroplast NTT proteins showed that homologs in chloroplasts from plants, and green, red, stramenopile and glaucocystophyte algae are monophyletic. In contrast, the evolutionary relationships of the bacterial counterparts appear highly complex. In the presented phylogeny, NTT proteins of C. caryophila and H. obtusa are only distantly related to one another, although these two taxa are close relatives in 16S rRNA trees. The tree topology indicates that some bacterial NTT paralogs have arisen by gene duplications and others by horizontal transfer.

Author: Tohri, A.; Suzuki, T.; Okuyama, S.; Kamino, K.; Motoki, A.; Hirano, M.; Ohta, H.; Shen, J. R.; Yamamoto, Y.; Enami, I.
Year: 2002
Title: Comparison of the structure of the extrinsic 33 kDa protein from different organisms
Journal: Plant Cell Physiol
Volume: 43
Issue: 4
Pages: 429-439
Date: Apr
Abstract: The psbO gene encoding the extrinsic 33 kDa protein of oxygen-evolving photosystem II (PSII) complex was cloned and sequenced from a red alga, Cyanidium caldarium. The gene encodes a polypeptide of 333 residues, of which the first 76 residues served as transit peptides for transfer across the chloroplast envelope and thylakoid membrane. The mature protein consists of 257 amino acids with a calculated molecular mass of 28,290 Da. The sequence homology of the mature 33 kDa protein was 42.9-50.8% between the red alga and cyanobacteria, and 44.7-48.6% between the red alga and higher plants. The cloned gene was expressed in Escherichia coli, and the recombinant protein was purified, subjected to protease-treatments. The cleavage sites of the 33 kDa protein by chymotrypsin or V8 protease were determined and compared among a cyanobacterium (Synechococcus elongatus), a euglena (Euglena gracilis), a green alga (Chlamydomonas reinhardtii) and two higher plants (Spinacia oleracea and Oryza sativa). The cleavage sites by chymotrypsin were at 156F and 190F for the cyanobacterium, 159M, 160F and 192L for red alga, 11Y and 151F for euglena, 10Yand 150F for green alga, and 16Y for spinach, respectively. The cleavage sites by V8 protease were at 181E (cyanobacterium), 182E and 195E (red alga), 13E, 67E, 69E, 153D and 181E (euglena), 176E and 180E (green alga), and 18E or 19E (higher plants). Since most of the residues at these cleavage sites were conserved among the six organisms, the results indicate that the structure of the 33 kDa protein, at least the structure based on the accessibility by proteases, is different among these organisms. In terms of the cleavage sites, the structure of the 33 kDa protein can be divided into three major groups: cyanobacterial and red algal-type has cleavage sites at residues around 156-195, higher plant-type at residues 16-19, and euglena and green algal-type at residues of both cyanobacterial and higher plant-types.

Author: Smith, A. C.; Purton, S.
Year: 2002
Title: The transcriptional apparatus of algal plastids
Journal: Eur. J. Phycol.
Volume: 37
Issue: 3
Pages: 301-311
Date: Aug
Abstract: The plastid organelle of plants, eukaryotic algae and apicomplexan protists contains its own DNA genome (the 'plastome'). In higher plants, at least two RNA polymerases have been shown to participate in the transcription of plastid genes. The multisubunit 'plastid-encoded plastid RNA polymerase' (PEP) is derived from the cyanobacterial ancestor of the organelle and is structurally similar to eubacterial RNA polymerases. The core subunits of PEP are encoded by genes on the plastome, whilst sigma-like transcription factors and other regulatory factors are encoded in the nucleus. In contrast, the 'nuclear-encoded plastid RNA polymerase' (NEP) is a single-subunit enzyme related to the T3/T7 bacteriophage and mitochondrial RNA polymerases that is believed to have arisen by duplication of the nuclear gene for the mitochondrial enzyme. The situation in algal plastids is less well understood. All algal groups, apart from possibly the dinoflagellates, possess a PEP but it is far from clear whether any possess additional plastid RNA polymerases. In this article we review what is known about the transcription apparatus of algal plastids, and examine the evidence for and against the presence of NEPs.
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Author: Okano, Y.; Mizohata, E.; Xie, Y.; Matsumura, H.; Sugawara, H.; Inoue, T.; Yokota, A.; Kai, Y.
Year: 2002
Title: X-ray structure of Galdieria Rubisco complexed with one sulfate ion per active site
Journal: FEBS Lett
Volume: 527
Issue: 1-3
Pages: 33-36
Date: Sep 11
Abstract: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the reactions of carboxylation and oxygenation of ribulose-1,5-bisphosphate. These reactions require that the active site should be closed by a flexible loop (loop 6) of the large subunit. Rubisco from a red alga, Galdieria partita, has the highest specificity for carboxylation reaction among the Rubiscos hitherto reported. The crystal structure of unactivated Galdieria Rubisco has been determined at 2.6 A resolution. The electron density map reveals that a sulfate binds only to the P1 anion-binding site of the active site and the loop 6 is closed. Galdieria Rubisco has a unique hydrogen bond between the main chain oxygen of Val332 on the loop 6 and the epsilon-amino group of Gln386 of the same large subunit. This interaction is likely to be crucial to understanding for stabilizing the loop 6 in the closed state and to making a higher affinity for anionic ligands.

Author: Oesterhelt, C.; Gross, W.
Year: 2002
Title: Different sugar kinases are involved in the sugar sensing of Galdieria sulphuraria
Journal: Plant Physiol
Volume: 128
Issue: 1
Pages: 291-299
Date: Jan
Abstract: The unicellular acidophilic red alga Galdieria sulphuraria is a facultative heterotroph with a complex uptake system for sugars and polyols, consisting of at least 14 transporters. Upon transfer to heterotrophic conditions, these transporters were induced simultaneously. Once induced, transporters for common hexoses and pentoses are apparently not down-regulated under heterotrophic conditions. Uptake of deoxysugars (FUC/Rha), however, was repressed by substrates metabolized via gluco-, galacto-, glycero-, or hexokinase, whereas substrates phosphorylated by xylulokinase had no effect. This indicates that several sugar kinases play a key role in sugar sensing. In contrast, polyol transporters were repressed only by glucose or its analogs but not by other sugars. This repression does not involve the activity of kinases. Most likely this type of glucose sensing is independent of metabolism and takes place prior to or during uptake. In its natural environment, these two different sensing mechanisms would enable the alga to utilize a mixture of different substrates in a most economic way by repressing dispensible transporters.

Author: Nagasaka, S.; Nishizawa, N. K.; Negishi, T.; Satake, K.; Mori, S.; Yoshimura, E.
Year: 2002
Title: Novel iron-storage particles may play a role in aluminum tolerance of Cyanidium caldarium
Journal: Planta
Volume: 215
Issue: 3
Pages: 399-404
Date: Jul
Abstract: Cyanidium caldarium (Tilden) Geitler, a unicellular red alga, has extraordinarily high aluminum (Al) tolerance. Algal cells cultured in the presence or absence of Al were subjected to transmission electron microscopy and energy dispersive X-ray analysis. Substantial changes to the thylakoid lumens were observed for the algal cells cultured in medium containing 200 mM Al, while other organelles were largely unaffected. Several spherical electron-dense bodies were found in the cytoplasm near the nucleus of both of the control and Al-treated cells. Although high levels of Fe and P were found in the bodies of control cells, immunocytochemical and morphological analysis data did not match the criteria established for Fe-accumulating substances like ferritin and phytate. In addition to these elements, Al was found in the bodies of the Al-treated cells. These results suggest that the electron-dense bodies function as an Fe-storage site under normal culture conditions, and that sequestration of Al in these bodies contributes to the high Al tolerance exhibited by C. caldarium.

Author: Muramoto, T.; Tsurui, N.; Terry, M. J.; Yokota, A.; Kohchi, T.
Year: 2002
Title: Expression and biochemical properties of a ferredoxin-dependent heme oxygenase required for phytochrome chromophore synthesis
Journal: Plant Physiol
Volume: 130
Issue: 4
Pages: 1958-1966
Date: Dec
Abstract: The HY1 gene of Arabidopsis encodes a plastid heme oxygenase (AtHO1) required for the synthesis of the chromophore of the phytochrome family of plant photoreceptors. To determine the enzymatic properties of plant heme oxygenases, we have expressed the HY1 gene (without the plastid transit peptide) in Escherichia coli to produce an amino terminal fusion protein between AtHO1 and glutathione S-transferase. The fusion protein was soluble and expressed at high levels. Purified recombinant AtHO1, after glutathione S-transferase cleavage, is a hemoprotein that forms a 1:1 complex with heme. In the presence of reduced ferredoxin, AtHO1 catalyzed the formation of biliverdin IXalpha from heme with the concomitant production of carbon monoxide. Heme oxygenase activity could also be reconstituted using photoreduced ferredoxin generated through light irradiation of isolated thylakoid membranes, suggesting that ferredoxin may be the electron donor in vivo. In addition, AtHO1 required an iron chelator and second reductant, such as ascorbate, for full activity. These results show that the basic mechanism of heme cleavage has been conserved between plants and other organisms even though the function, subcellular localization, and cofactor requirements of heme oxygenases differ substantially.
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Author: Kobayashi, T.; Takahara, M.; Miyagishima, S. Y.; Kuroiwa, H.; Sasaki, N.; Ohta, N.; Matsuzaki, M.; Kuroiwa, T.
Year: 2002
Title: Detection and localization of a chloroplast-encoded HU-like protein that organizes chloroplast nucleoids
Journal: Plant Cell
Volume: 14
Issue: 7
Pages: 1579-1589
Date: Jul
Abstract: Chloroplast DNA (cpDNA) is packed into discrete structures called chloroplast nucleoids (cp-nucleoids). The structure of cpDNA is thought to be important for its maintenance and regulation. In bacteria and mitochondria, histone-like proteins (such as HU and Abf2, respectively) are abundant and play important roles in DNA organization. However, a primary structural protein has yet to be found in cp-nucleoids. Here, we identified an abundant DNA binding protein from isolated cp-nucleoids of the primitive red alga Cyanidioschyzon merolae. The purified protein had sequence homology with the bacterial histone-like protein HU, and it complemented HU-lacking Escherichia coli mutants. The protein, called HC (histone-like protein of chloroplast), was encoded by a single gene (CmhupA) in the C. merolae chloroplast genome. Using immunofluorescence and immunoelectron microscopy, we demonstrated that HC was distributed uniformly throughout the entire cp-nucleoid. The protein was expressed constitutively throughout the cell and the chloroplast division cycle, and it was able to condense DNA. These results indicate that HC, a bacteria-derived histone-like protein, primarily organizes cpDNA into the nucleoid.

Author: Kitajima, S.; Ueda, M.; Sano, S.; Miyake, C.; Kohchi, T.; Tomizawa, K.; Shigeoka, S.; Yokota, A.
Year: 2002
Title: Stable form of ascorbate peroxidase from the red alga Galdieria partita similar to both chloroplastic and cytosolic isoforms of higher plants
Journal: Biosci Biotechnol Biochem
Volume: 66
Issue: 11
Pages: 2367-2375
Date: Nov
Abstract: Depletion of the electron donor ascorbate causes rapid inactivation of chloroplastic ascorbate peroxidase (APX) of higher plants, while cytosolic APX is stable under such conditions. Here we report the cloning of cDNA from Galdieria partita, a unicellular red alga, encoding a novel type of APX (APX-B). The electrophoretic mobility, Km values, kcat and absorption spectra of recombinant APX-B produced in Escherichia coli were measured. Recombinant APX-B remained active for at least 180 min after depletion of ascorbate. The amino-terminal half of APX-B, which forms the distal pocket of the active site, was richer in amino acid residues conserved in chloroplastic APXs of higher plants rather than cytosolic APXs. In contrast, the sequence of the carboxyl-terminal half, which forms the proximal pocket, was similar to that of the cytosolic isoform. The stability of APX-B might be due to its cytosolic isoform-like structure of the carboxyl-terminal half.

Author: Kawashima, T.; Amano, N.; Higuchi, S.; Minezaki, Y.; Clowney, L.; Ishijima, S. A.; Koike, H.; Aramaki, H.; Nunoshiba, T.; Kawamoto, T.; Yokoyama, K.; Kimura, S.; Makino, K.; Suzuki, M.
Year: 2002
Title: Nucleotide sequences of the plastid and nuclear chromosome I of the unicellular red alga Cyanidioschyzon merolae
Journal: Proc. Jpn. Acad. Ser. B-Phys. Biol. Sci.
Volume: 78
Issue: 10
Pages: 299-304
Date: Dec
Abstract: We have determined the complete nucleotide sequence of the plastid (149,705 bps), and the nucleotide sequence of the smallest chromosome (422,021 bps of chromosome I) of the unicellular red alga Cyanidioschyzon merolae. Fragments of other chromosomes have been also sequenced, altogether covering 1,313,748 bps. Both the process of this determination, and the determined sequences of the plastid and chromosome I are reported in this paper. The sequence of chromosome I does not have a telomere repeat at either end. Lines of evidence indicate that the undetermined parts are short, similar to500 bps each.
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Author: Gross, W.; Oesterhelt, C.; Tischendorf, G.; Lederer, F.
Year: 2002
Title: Characterization of a non-thermophilic strain of the red algal genus Galdieria isolated from Soos (Czech Republic)
Journal: Eur. J. Phycol.
Volume: 37
Issue: 3
Pages: 477-482
Date: Aug
Abstract: Volcanic areas with highly acidic solfatara soils and temperatures of up to 56 degreesC are inhabited by the red algal genus Galdieria. We examined three highly acidic but non- volcanic habitats in the western part of the Czech Republic for the occurrence of this red alga. In soil samples from the National Nature Reserve of Soos we found, together with Euglena mutabilis, Pseudococcomyxa situplex and species of Chlorella, a new strain of Galdieria. In contrast to all other Galdieria strains described so far, the strain from Soos exhibited a low temperature optimum for growth of about 30 degreesC. Other properties, such as the substrate spectrum for heterotrophic growth, ultrastructure, fatty acid composition, thermostability of enzymes and the nitrogen source, showed no obvious differences from other strains of Galdieria. Within a phylogenetic tree based on 18S rRNA sequence data, the strain from Soos occupied a position at the base of the 'Galdieria'- branch. Our findings indicate that the genus Galdieria is not restricted to volcanic and mining areas and that strains of Galdieria are able to compete successfully with green algae in habitats like Soos.
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Author: Donachie, S. P.; Christenson, B. W.; Kunkel, D. D.; Malahoff, A.; Alam, M.
Year: 2002
Title: Microbial community in acidic hydrothermal waters of volcanically active White Island, New Zealand
Journal: Extremophiles
Volume: 6
Issue: 5
Pages: 419-425
Date: Oct
Abstract: We report the first description of the microbial community in a stream of acidic hydrothermal waters on volcanically active White Island, New Zealand, using both molecular and microbiological methods. alpha- and beta-Proteobacteria, green- sulfur bacteria, and uncultured Firmicutes were identified from the community DNA-based 16s rRNA gene library. The same bacterial groups and the Rhodophyte Cyanidium caldarium were represented in enrichment cultures. C caldarium, two Firmicutes and an acidophilic alpha-Proteobacterium, Acidiphilium cryptum, were brought into pure culture. Bacteria cultured from the stream grow at pH greater than or equal to 2, and the Cyanidium grows at pH 0.2.
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Author: Whitney, S. M.; Baldet, P.; Hudson, G. S.; Andrews, T. J.
Year: 2001
Title: Form I Rubiscos from non-green algae are expressed abundantly but not assembled in tobacco chloroplasts
Journal: Plant J
Volume: 26
Issue: 5
Pages: 535-547
Date: Jun
Abstract: Non-green algae have Rubiscos that are phylogenetically distinct from their counterparts in green algae and higher plants. Some non-green-algal Rubiscos are more specific for CO2, relative to O2, than higher-plant Rubiscos, sometimes coupled with lower Michaelis constants for CO2. If these Rubiscos could be substituted for the higher-plant enzyme, and if they functioned successfully in the higher-plant chloroplast and were regulated appropriately, they would improve the CO2 use and quantum efficiency of higher-plant photosynthesis. To assess the feasibility of expressing non-green algal Rubiscos in higher-plant chloroplasts, we inserted the rbcLS operons from the rhodophyte Galdieria sulphuraria and the diatom Phaeodactylum tricornutum into the inverted repeats of the plastid genome of tobacco, leaving the tobacco rbcL gene unaltered. Homoplasmic transformants were selected. The transgenes directed the synthesis of abundant amounts of transcripts and both subunits of the foreign Rubiscos. In some circumstances, leaves of the transformants with the P. tricornutum Rubisco contained as much foreign Rubisco protein as endogenous tobacco Rubisco (>30% of the soluble leaf protein). However, the subunits of the foreign Rubiscos were not properly folded and/or assembled. All the foreign large subunits and most of the foreign small subunits were recovered in the insoluble fractions of leaf extracts. Edman sequencing yielded the expected N-terminal sequences for the foreign small subunits but the N-termini of the foreign large subunits were blocked. Accumulation of large amounts of denatured foreign Rubisco in the leaves, particularly of the P. tricornutum transformants, caused a reduction in the amount of tobacco Rubisco present, with concomitant reductions in leaf CO2 assimilation and plant growth.

Author: Sano, S.; Ueda, M.; Kitajima, S.; Takeda, T.; Shigeoka, S.; Kurano, N.; Miyachi, S.; Miyake, C.; Yokota, A.
Year: 2001
Title: Characterization of ascorbate peroxidases from unicellular red alga Galdieria partita
Journal: Plant Cell Physiol
Volume: 42
Issue: 4
Pages: 433-440
Date: Apr
Abstract: Galdieria partita, a unicellular red alga isolated from acidic hot springs and tolerant to sulfur dioxide, has at least two ascorbate peroxidase (APX) isozymes. This was the first report to demonstrate that two isozymes of APX are found in algal cells. Two isozymes were separated from each other at the hydrophobic chromatography step of purification and named APX-A and APX-B after the elution order in the chromatography. APX-B accounted for 85% of the total activity. Both isozymes were purified. APXs from Galdieria were monomers whose molecular weights were about 28,000, similar to stromal APX of higher plants. APX-A cross-reacted with monoclonal antibody raised against APX of Euglena gracilis in immunoblotting, but APX-B did not, although the antibody can recognize all other APXs tested. The amino-terminal sequences of APX-A and -B from Galdieria had some homology with each other but little homology with those from other sources. Their Km values for ascorbate and hydrogen peroxide were comparable with those of APX from higher plants. Unlike the green algal enzymes, the donor specificities of Galdieria APXs were as high as those of plant chloroplastic APX. On the contrary, these APXs reduced tertiary-butyl hydroperoxide as an electron acceptor as APXs from Euglena and freshwater Chlamydomonas do. The inhibition of APX-A and -B by cyanide and azide, and characteristics of their light absorbance spectra indicated that they were heme peroxidases.

Author: Muravenko, O. V.; Selyakh, I. O.; Kononenko, N. V.; Stadnichuk, I. N.
Year: 2001
Title: Chromosome numbers and nuclear DNA contents in the red microalgae Cyanidium caldarium and three Galdieria species
Journal: Eur. J. Phycol.
Volume: 36
Issue: 3
Pages: 227-232
Date: Aug
Abstract: An image analysis system was used to count and measure acetoorcein-stained mitotic chromosomes of the acidothermophilic unicellular red algae Galdieria maxima, G. partita, G. sulphuraria and Cyanidium caldarium (Cyanidiophyceae). Chromosome numbers fell into two groups: n = 2 for all three species of Galdieria and n = 5(7) for C. caldarium. It seems that a separation of C. caldarium from Galdieria is karyologically justified. A chromosome number of 2 appears to be indicative of the genus Galdieria and could be used as a marker to distinguish this taxon from Cyanidium. The two smaller chromosomes in the karyotype of C. caldarium were about 0.4 mum. long whereas the other three were 0.5-0.7 mum long. In karyotypes of Galdieria species, the two chromosomes differed in length, the smaller chromosome ranging from 0.8 to 1.8 mum and the larger one from 1.2 to 2.3 mum. The visualization of these extremely small chromosomes was possible due to pretreatment of the cells with the DNA intercalator 9- aminoacridine. The mean absolute length of each chromosome of the three members of Galdieria had statistically significant interspecies differences. Nuclear IC DNA contents were estimated in the algal cells by the Feulgen technique. All species investigated had genome sizes of 1.50-2.25 x 10(-2) pg. Thus it seems that the members of Cyanidiophyceae have the smallest known genomes of all photosynthetic eukaryotes.
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Author: Miyagishima, Sy; Takahara, M.; Mori, T.; Kuroiwa, H.; Higashiyama, T.; Kuroiwa, T.
Year: 2001
Title: Plastid division is driven by a complex mechanism that involves differential transition of the bacterial and eukaryotic division rings
Journal: Plant Cell
Volume: 13
Issue: 10
Pages: 2257-2268
Date: Oct
Abstract: During plastid division, two structures have been detected at the division site in separate analyses. The plastid-dividing ring can be detected by transmission electron microscopy as two (or three) electron-dense rings: an outer ring on the cytosolic face of the outer envelope, occasionally a middle ring in the intermembrane space, and an inner ring on the stromal face of the inner envelope. The FtsZ ring, which plays a central role in bacterial division, also is involved in plastid division and is believed to have descended to plastids from cyanobacterial endosymbiosis. The relationship between the two structures is not known, although there is discussion regarding whether they are identical. Biochemical and immunocytochemical investigations, using synchronized chloroplasts of the red alga Cyanidioschyzon merolae, showed that the plastid FtsZ ring is distinct and separable from the plastid-dividing ring. The FtsZ ring localizes in stroma and faces the inner plastid-dividing ring at the far side from the inner envelope. The FtsZ ring and the inner and outer plastid-dividing rings form in that order before plastid division. The FtsZ ring disappears at the late stage of constriction before dissociation of the plastid-dividing ring, when the constriction is still in progress. Our results suggest that the FtsZ ring;-based system, which originated from a plastid ancestor, cyanobacteria, and the plastid-dividing ring;-based system, which probably originated from host eukaryotic cells, form a complex and are involved in plastid division by distinct modes.

Author: Miyagishima, S.; Kuroiwa, H.; Kuroiwa, T.
Year: 2001
Title: The timing and manner of disassembly of the apparatuses for chloroplast and mitochondrial division in the red alga Cyanidioschyzon merolae
Journal: Planta
Volume: 212
Issue: 4
Pages: 517-528
Date: Mar
Abstract: The timing and manner of disassembly of the apparatuses for chloroplast division (the plastid-dividing ring; PD ring) and mitochondrial division (the mitochondrion-dividing ring; MD ring) were investigated in the red alga Cyanidioschyzon merolae De Luca, Taddei and Varano. To do this, we synchronized cells both at the final stage of and just after chloroplast and mitochondrial division, and observed the rings in three dimensions by transmission electron microscopy. The inner (beneath the stromal face of the inner envelope) and middle (in the inter-membrane space) PD rings disassembled completely, and disappeared just before completion of chloroplast division. In contrast, the outer PD and MD rings (on the cytoplasmic face of the outer envelope) remained in the cytosol between daughter organelles after chloroplast and mitochondrial division. The outer rings started to disassemble and disappear from their surface just after organelle division, initially clinging to the outer envelopes at both edges before detaching. The results suggest that the two rings inside the chloroplast disappear just before division, and that this does not interfere with completion of division, while the outer PD and MD rings function throughout and complete chloroplast and mitochondrial division. These results, together with previous studies of C. merolae, disclose the entire cycle of change of the PD and MD rings.

Author: Miyagishima, S.; Takahara, M.; Kuroiwa, T.
Year: 2001
Title: Novel filaments 5 nm in diameter constitute the cytosolic ring of the plastid division apparatus
Journal: Plant Cell
Volume: 13
Issue: 3
Pages: 707-721
Date: Mar
Abstract: The plastid division apparatus (called the plastid-dividing ring) has been detected in several plant and algal species at the constricted region of plastids by transmission electron microscopy. The apparatus is composed of two or three rings: an outer ring in the cytosol, an inner ring in the stroma, and a middle ring in the intermembrane space. The components of these rings are not clear. FtsZ, which forms the bacterial cytokinetic ring, has been proposed as a component of both the inner and outer rings. Here, we present the ultrastructure of the outer ring at high resolution. To visualize the outer ring by negative staining, we isolated dividing chloroplasts from a synchronized culture of a red alga, Cyanidioschyzon merolae, and lysed them with nonionic detergent Nonidet P-40. Nonidet P-40 extracted primarily stroma, thylakoids, and the inner and middle rings, leaving the envelope and outer ring largely intact. Negative staining revealed that the outer ring consists of a bundle of 5-nm filaments in which globular proteins are spaced 4.8 nm apart. Immunoblotting using an FtsZ-specific antibody failed to show immunoreactivity in the fraction containing the filament. Moreover, the filament structure and properties are unlike those of known cytoskeletal filaments. The bundle of filaments forms a very rigid structure and does not disassemble in 2 M urea. We also identified a dividing phase-specific 56-kD protein of chloroplasts as a candidate component of the ring. Our results suggest that the main architecture of the outer ring did not descend from cyanobacteria during the course of endosymbiosis but was added by the host cell early in plant evolution.

Author: Hoober, J. K.; Eggink, L. L.
Year: 2001
Title: A potential role of chlorophylls b and c in assembly of light-harvesting complexes
Journal: FEBS Lett
Volume: 489
Issue: 1
Pages: 1-3
Date: Jan 26
Abstract: Chlorophyll (Chl)-containing light-harvesting complexes (LHCs) in chloroplasts of plant and algal cells usually include an oxidized Chl (Chl b or c) in addition to Chl a. Oxidation of peripheral groups on the tetrapyrrole structure increases the Lewis acid strength of the central Mg atom. We propose that the resulting stronger coordination bonds between oxidized Chls and ligands in LHC apoproteins (LHCPs) stabilize the initial intermediates and thus promote assembly of LHCs within the chloroplast envelope.

Author: Heilmann, I.; Perera, I. Y.; Gross, W.; Boss, W. F.
Year: 2001
Title: Plasma membrane phosphatidylinositol 4,5-bisphosphate levels decrease with time in culture
Journal: Plant Physiol
Volume: 126
Issue: 4
Pages: 1507-1518
Date: Aug
Abstract: During the stationary phase of growth, after 7 to 12 d in culture, the levels of phosphatidylinositol 4,5-bisphosphate (PtdInsP(2)) decreased by 75% in plasma membranes of the red alga Galdieria sulphuraria. Concomitant with the decrease in PtdInsP(2) levels in plasma membranes, there was an increase in PtdInsP(2) in microsomes, suggesting that the levels of plasma membrane PtdInsP(2) are regulated differentially. The decline of PtdInsP(2) in plasma membranes was accompanied by a 70% decrease in the specific activity of PtdInsP kinase and by reduced levels of protein cross-reacting with antisera against a conserved PtdInsP kinase domain. Upon osmotic stimulation, the loss of PtdInsP(2)from the plasma membrane increased from 10% in 7-d-old cells to 60% in 12-d-old cells, although the levels of inositol 1,4,5-trisphosphate (InsP(3)) produced in whole cells were roughly equal at both times. When cells with low plasma membrane PtdInsP(2) levels were osmotically stimulated, a mild osmotic stress (12.5 mM KCl) activated PtdInsP kinase prior to InsP(3) production, whereas in cells with high plasma membrane PtdInsP(2), more severe stress (250 mM KCl) was required to induce an increase in PtdInsP kinase activity. The differential regulation of a plasma membrane signaling pool of PtdInsP(2) is discussed with regard to the implications for understanding the responsive state of cells.

Author: Gross, W.; Heilmann, I.; Lenze, D.; Schnarrenberger, C.
Year: 2001
Title: Biogeography of the Cyanidiaceae (Rhodophyta) based on 18S ribosomal RNA sequence data
Journal: Eur. J. Phycol.
Volume: 36
Issue: 3
Pages: 275-280
Date: Aug
Abstract: The only eukaryotes found in highly acidic environments (pH 0.5-3) with elevated temperatures (up to 56 degreesC) are three species of unicellular red algae: Cyanidioschyzon merolae, Cyanidium caldarium and Galdieria sulphuraria. These habitats are scattered all over the world and are usually very small. Because all three species are strictly acidophilic and will not tolerate desiccation, distribution by wind or water seems very unlikely. The populations in the various habitats might have been isolated for very long times, providing a unique opportunity to observe a significant degree of independent evolution under strong, selective pressure. We investigated the biogeography of 18 isolates of these red algae by comparison of partial sequences of the 18S rRNA. A gene tree based on ISS rRNA assigns 15 strains to one branch with high bootstrap values. These isolates share the feature of facultative heterotrophy, whether or not they were originally placed in the genus Galdieria. The remaining three strains - Galdieria maxima, C. merolae and C. caldarium - form a sister clade to this group. The exact position of these two groups in relation to other red algae remains unresolved. The evolutionary distance between individual Galdieria strains is high, indicating that within this genus several races have developed significantly altered 18S sequences. Our comparison of 18S sequences from thermo-acidophilic red algae indicates that even within a seemingly homogeneous group of eukaryotic organisms the limits of phylogenetic analysis may be reached.
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Author: Asada, R.; Tazaki, K.
Year: 2001
Title: Silica biomineralization of unicellular microbes under strongly acidic conditions
Journal: Can. Mineral.
Volume: 39
Pages: 1-16
Date: Feb
Abstract: Silica biomineralization associated with unicellular microbes (Cyanidium caldarium) living in strongly acidic hot springs were observed by electron microscopy. The unicellular microbes form green biomats undergoing photosynthesis in Kamuiwakka Falls, Hokkaido, Japan. The hot-spring water is strongly acidic, with pH less than 2, and rich in S. Electron microscopy observations showed that the cell walls of unicellular microbes served as sires for nucleation of silica, polymerization of silicic acid and adhesion of colloidal silica. The precipitates formed an amorphous silica crust on the cell walls, which consist of granular silica spherules with a uniform size. The spherules commonly assimilate the cell walls. Data from X-ray diffraction and electron diffraction of the silica crusts reveal that the crusts are amorphous or of low crystallinity. Electron-dispersion X-ray spectroscopy also showed that the crusts are mainly composed of Si with traces of S and Cl. The unicellular microbes have a double-layer cell wall; therefore, silica crusts may form a double laver. FT-IR spectra of cells with and without silica crusts indicated that N-H, C=O and C-N- H bands were derived from peptides in cells, whereas the Si-O band was derived from silica crusts. Some models also are suggested on the interaction between cell wall and silica under strongly acidic conditions. Processes of silica biomineralization of unicellular microbes as described in this paper have profound implications for evolution of siliciferous microbes.
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Author: Yoshimura, E.; Nagasaka, S.; Satake, K.; Mori, S.
Year: 2000
Title: Mechanism of aluminium tolerance in Cyanidium caldarium
Journal: Hydrobiologia
Volume: 433
Issue: 1-3
Pages: 57-60
Date: Aug
Abstract: Cyanidium caldarium, an acidophilic, thermophilic red alga, specifically tolerates Al. The tolerance increases at lower culture temperatures. The intracellular Al concentration is kept at low levels, especially when the cells are cultured at lower temperatures. Lower Al incorporation accounts for the Al tolerance in this alga. Fe incorporation antagonizes the Al incorporation, implying that Fe transporters incorporate Al ions. Treatment with an uncoupler, carbonylcyanide m- chlorophenylhydrazone, increases the intracellular concentration of Al. These results support the hypothesis that Al ions taken up by the algal cells are exported by an energy- dependent mechanism.
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Author: Takahara, M.; Takahashi, H.; Matsunaga, S.; Sakai, A.; Kawano, S.; Kuroiwa, T.
Year: 2000
Title: Isolation, characterization, and chromosomal mapping of an ftsZ gene from the unicellular primitive red alga Cyanidium caldarium RK-1
Journal: Curr Genet
Volume: 37
Issue: 2
Pages: 143-151
Date: Feb
Abstract: The FtsZ protein is involved in eukaryote plastid division, but there is little information on its involvement in the plastid-dividing apparatus. To investigate the relationship between FtsZ and the plastid-dividing ring, the ftsZ gene was isolated from the unicellular primitive red alga Cyanidium caldarium RK-1. Comparison of several prokaryotic and eukaryotic FtsZ proteins shows that there are six highly conserved domains in the core region of FtsZ. To determine the chromosomal location of ftsZ, we first determined the electrophoretic karyotype of C. caldarium RK-1. Southern-hybridization analysis combined with CHEF revealed the chromosomes on which the ftsZ gene exist. Northern-hybridization analysis indicated that the C. caldarium RK-1 ftsZ gene is transcribed as a 1.9-kb molecule, and that the transcripts specifically accumulate just before plastid division. Phylogenetic analysis indicated that C. caldarium RK-1 and other eukaryotic ftsZ genes are the descendants of cyanobacterial ftsZ genes, supporting the current agreement that FtsZ is involved in plastid division.

Author: Oliveira, M. C.; Bhattacharya, D.
Year: 2000
Title: Phylogeny of the Bangiophycidae (Rhodophyta) and the secondary endosymbiotic origin of algal plastids
Journal: Am J Bot
Volume: 87
Issue: 4
Pages: 482-492
Date: Apr
Abstract: The Rhodophyta (red algae) are composed of the subclasses Bangiophycidae and Florideophycidae. Two evolutionarily interesting features of the Bangiophycidae are: (1) they are the ancestral pool from which the more morphologically complex taxa in the Florideophycidae have arisen and (2) they are the sources of the plastids, through secondary endosymbioses, for the Cryptophyta, Haptophyta, and the Heterokonta. To understand Bangiophycidae phylogeny and to gain further insights into red algal secondary endosymbioses, we sequenced the plastid-encoded small subunit ribosomal DNA (rDNA) coding region from nine members of this subclass and from two members of the Florideophycidae. These sequences were included in phylogenetic analyses with all available red algal plus chlorophyll a + c algal plastid rDNA coding regions. Our results are consistent with a monophyletic origin of the Florideophycidae with these taxa forming a sister group of the Bangiales. The Bangiophycidae is of a paraphyletic origin with orders such as the Porphyridiales polyphyletic and distributed over three independent red algal lineages. The plastids of the heterokonts are most closely related to members of the Cyanidium-Galdieria group of Porphyridiales and are not directly related to cryptophyte and haptophyte plastids. The phylogenies provide strong evidence for the independent origins of these "complex" algal plastids from different members of the Bangiophycidae.

Author: Marquardt, J.; Wans, S.; Rhiel, E.; Randolf, A.; Krumbein, W. E.
Year: 2000
Title: Intron-exon structure and gene copy number of a gene encoding for a membrane-intrinsic light-harvesting polypeptide of the red alga Galdieria sulphuraria
Journal: Gene
Volume: 255
Issue: 2
Pages: 257-265
Date: Sep 19
Abstract: Genes for light-harvesting proteins (lhc genes) of higher plants are well examined. However, little is known about the corresponding genes of algae, although this knowledge might give valuable information about the evolution of photosynthetic antennae. In the case of rhodophytes only two cDNA sequences from a single organism, Porphyridium cruentum, have been published. Here we describe an additional sequence from another species, the thermo-acidophilic red alga Galdieria sulphuraria. For the first time also a genomic sequence for a red algal lhc gene is presented. From a cDNA library of G. sulphuraria we isolated a clone containing an open reading frame for a protein of 302 amino acids with a deduced molecular mass of 33.86kDa. It shares major structural features with eukaryotic light-harvesting polypeptides. A proposed cleavage site between transit peptide and mature protein gives rise to a transit peptide of 119 amino acids and a mature protein of 183 residues. Hydropathy analysis suggests that the mature protein consists of three transmembrane helices. Several amino acid residues supposed to bind chlorophyll a and chlorophyll b in higher plants are conserved. The protein shows up to 69% identity and 81% similarity to the Porphyridium polypeptides in the transmembrane helices 1 and 3. Using oligonucleotides annealing in the regions of the start and stop codons of the gene as primers, a DNA sequence was amplified from nuclear G. sulphuraria DNA by PCR. Compared with the cDNA clone, this sequence contains five additional intervening DNA strings of 50-74bp length. Four of them show typical features of spliceosomal introns with GT-AG borders, and the fifth differs by starting with GC. Three of the supposed introns are located in similar positions as introns of higher plant light-harvesting proteins. Southern blotting and hybridization experiments indicate that G. sulphuraria contains at least three copies of this gene.

Author: Glöckner, G.; Rosenthal, A.; Valentin, K.
Year: 2000
Title: The structure and gene repertoire of an ancient red algal plastid genome
Journal: J Mol Evol
Volume: 51
Issue: 4
Pages: 382-390
Date: Oct
Abstract: Photosynthetic eukaryotes can, according to features of their chloroplasts, be divided into two major groups: the red and the green lineage of plastid evolution. To extend the knowledge about the evolution of the red lineage we have sequenced and analyzed the chloroplast genome (cp-genome) of Cyanidium caldarium RK1, a unicellular red alga (AF022186). The analysis revealed that this genome shows several unusual structural features, such as a hypothetical hairpin structure in a gene-free region and absence of large repeat units. We provide evidence that this structural organization of the cp-genome of C. caldarium may be that of the most ancient cp-genome so far described. We also compared the cp-genome of C. caldarium to the other known cp-genomes of the red lineage. The cp-genome of C. caldarium cannot be readily aligned with that of Porphyra purpurea, a multicellular red alga, or Guillardia theta due to a displacement of a region of the cp-genome. The phylogenetic tree reveals that the secondary endosymbiosis, through which G. theta evolved, took place after the separation of the ancestors of C. caldarium and P. purpurea. We found several genes unique to the cp-genome of C. caldarium. Five of them seem to be involved in the building of bacterial cell envelopes and may be responsible for the thermotolerance of the chloroplast of this alga. Two additional genes may play a role in stabilizing the photosynthetic machinery against salt stress and detoxification of the chloroplast. Thus, these genes may be unique to the cp-genome of C. caldarium and may be required for the endurance of the extreme living conditions of this alga.

Author: Enami, I.; Yoshihara, S.; Tohri, A.; Okumura, A.; Ohta, H.; Shen, J. R.
Year: 2000
Title: Cross-reconstitution of various extrinsic proteins and photosystem II complexes from cyanobacteria, red algae and higher plants
Journal: Plant Cell Physiol
Volume: 41
Issue: 12
Pages: 1354-1364
Date: Dec
Abstract: Photosystem II (PSII) contains different extrinsic proteins required for oxygen evolution among different organisms. Cyanobacterial PSII contains the 33 kDa, 12 kDa proteins and cytochrome (cyt) c-550; red algal PSII contains a 20 kDa protein in addition to the three homologous cyanobacterial proteins; whereas higher plant PSII contains the 33 kDa, 23 kDa and 17 kDa proteins. In order to understand the binding and functional properties of these proteins, we performed cross-reconstitution experiments with combinations of PSII and extrinsic proteins from three different sources: higher plant (spinach), red alga (Cyanidium caldarium) and cyanobacterium (Synechococcus vulcanus). Among all of the extrinsic proteins, the 33 kDa protein is common to all of the organisms and is totally exchangeable in binding to PSII from any of the three organisms. Oxygen evolution of higher plant and red algal PSII was restored to a more or less similar level by binding of any one of the three 33 kDa proteins, whereas oxygen evolution of cyanobacterial PSII was restored to a larger extent with its own 33 kDa protein than with the 33 kDa protein from other sources. In addition to the 33 kDa protein, the red algal 20 kDa, 12 kDa proteins and cyt c-550 were able to bind to cyanobacterial and higher plant PSII, leading to a partial restoration of oxygen evolution in both organisms. The cyanobacterial 12 kDa protein and cyt c-550 partially bound to the red algal PSII, but this binding did not restore oxygen evolution. The higher plant 23 kDa and 17 kDa proteins bound to the cyanobacterial and red algal PSII only through non-specific interactions. Thus, only the red algal extrinsic proteins are partially functional in both the cyanobacterial and higher plant PSII, which implies a possible intermediate position of the red algal PSII during its evolution from cyanobacteria to higher plants.

Author: Eisele, L. E.; Bakhru, S. H.; Liu, X.; MacColl, R.; Edwards, M. R.
Year: 2000
Title: Studies on C-phycocyanin from Cyanidium caldarium, a eukaryote at the extremes of habitat
Journal: Biochim Biophys Acta
Volume: 1456
Issue: 2-3
Pages: 99-107
Date: Jan 10
Abstract: C-Phycocyanin, a biliprotein, was purified from the red alga, Cyanidium caldarium. This alga grows at temperatures up to 57 degrees C, a very high temperature for a eukaryote, and at pH values down to 0.05. Using the chromophores on C-phycocyanin as naturally occurring reporter groups, the effects of temperature on the stability of the protein were studied by circular dichroism and absorption spectroscopy. The protein was unchanged from 10 to 50 degrees C, which indicates that higher temperatures are not required to cause the protein to be photosynthetically active. At 60 and 65 degrees C, which are above the temperatures at which the alga can survive, the protein undergoes irreversible denaturation. Gel-filtration column chromatography demonstrated that the irreversibility is caused by the dissociation of the trimeric protein to its constitutive polypeptides. Upon cooling, the alpha and beta polypeptides did not reassemble to the trimer. Unlike phycocyanins 645 and 612, the C-phycocyanin does not show a reversible conformational change at moderately high temperatures. At constant temperature, the C-phycocyanin was more stable than a mesophilic counterpart. It is designated a temperature-resistant protein.

Author: Cozzolino, S.; Caputo, P.; De Castro, O.; Moretti, A.; Pinto, G.
Year: 2000
Title: Molecular variation in Galdieria sulphuraria (Galdieri) Merola and its bearing on taxonomy
Journal: Hydrobiologia
Volume: 433
Issue: 1-3
Pages: 145-151
Date: Aug
Abstract: Cyanidium caldarium, Cyanidioschyzon merolae and Galdieria sulphuraria are three unicellular algae characteristic, of acid thermal environments. Recently, on the basis of morphological characters, three new species of Galdieria (G. partita, G. daedala, G. maxima ) isolated from acid-thermal springs in Russia have been instituted. A selected region of rbcL and the sequence of the intergenic spacer between the rbcL and rbcS have been amplified and sequenced from different Galdieria species and strains, in order to define molecular relationship among these interesting algae. The obtained cladogram shows that Cyanidium caldarium and Cyanidioschyzon merolae form a sister group which, in turn, is in a sister group relationship with Galdieria. This last genus is divided in two clades, one of which includes G. sulphuraria accessions from Naples (Italy), California, and Yellowstone and the other one includes G. sulphuraria accessions from Java (Indonesia) and from the Russian species. These results support the status of the genus Galdieria and suggest that G. daedala, G. maxima and G. partita are three very similar strains of G. sulphuraria; the rbcL variation within Galdieria accessions has a pattern which is broadly connected to the geographial distribution. The data obtained from the intergenic rbcL-rbcS spacer partly confirm those from the rbcL analysis.
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Author: Albertano, P.; Ciniglia, C.; Pinto, G.; Pollio, A.
Year: 2000
Title: The taxonomic position of Cyanidium, Cyanidioschyzon and Galdieria: an update
Journal: Hydrobiologia
Volume: 433
Issue: 1-3
Pages: 137-143
Date: Aug
Abstract: The ecophysiological, cytomorphological, biochemical and molecular data presently available for the acidophilic red algal species Cyanidium caldarium, Cyanidioschyzon merolae and Galdieria sulphuraria are summarised. The taxonomic position of the three genera is discussed and emendements to the generic diagnosis are presented.
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Author: Yoshimura, E.; Nagasaka, S.; Sato, Y.; Satake, K.; Mori, S.
Year: 1999
Title: Extraordinary high aluminium tolerance of the acidophilic thermophilic alga, Cyanidium caldarium
Journal: Soil Sci. Plant Nutr.
Volume: 45
Issue: 3
Pages: 721-724
Date: Sep
Abstract: A strain of an acidophilic, thermophilic alga, Cyanidium caldarium, was cultured in a medium containing various metal ions (Al, Cd, Cr, Cu, Mn, Ni, Zn). Among these metals, the alga tolerates especially high levels of Al: it can grow in a medium containing 200 mid Al, although the growth rate was reduced to 58%. The cellular Al concentration was kept at a considerably lower level as compared to the medium Al concentration. This may account for the Al tolerance of the alga. Treatment of the algal cells with carbonylcyanide m-chlorophenylhydrazone in the presence of Al increased the cellular Al concentration. It was suggested that energy-coupled Al exclusion mechanisms can operate in the alga.
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Author: Takahara, M.; Takahashi, H.; Matsunaga, S.; Sakai, A.; Kawano, S.; Kuroiwa, T.
Year: 1999
Title: Two types of ftsZ genes isolated from the unicellular primitive red alga Galdieria sulphuraria
Journal: Plant Cell Physiol
Volume: 40
Issue: 8
Pages: 784-791
Date: Aug
Abstract: FtsZ plays a crucial role in bacterial cell division, and may be involved in plastid division in eukaryotes. To investigate the evolution of the dividing apparatus from prokaryotes to eukaryotes, the ftsZ genes were isolated from the unicellular primitive red alga Galdieria sulphuraria. Two ftsZ genes (GsftsZ1 and GsftsZ2) were isolated. This suggests that duplication and divergence of the ftsZ gene occurred in an early stage of plant evolution. A comparison of the FtsZs of G. sulphuraria and other organisms shows that FtsZ is highly and universally conserved among prokaryotes, primitive eukaryotic algae, and higher plants. The GsftsZ2 gene seems to contain an intron. Southern hybridization analysis of the G. sulphuraria chromosomes separated by CHEF revealed that each ftsZ gene and its flanking region may be duplicated.

Author: Sugawara, H.; Yamamoto, H.; Shibata, N.; Inoue, T.; Okada, S.; Miyake, C.; Yokota, A.; Kai, Y.
Year: 1999
Title: Crystal structure of carboxylase reaction-oriented ribulose 1, 5-bisphosphate carboxylase/oxygenase from a thermophilic red alga, Galdieria partita
Journal: J Biol Chem
Volume: 274
Issue: 22
Pages: 15655-15661
Date: May 28
Abstract: Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1. 39) obtained from a thermophilic red alga Galdieria partita has the highest specificity factor of 238 among the Rubiscos hitherto reported. Crystal structure of activated Rubisco from G. partita complexed with the reaction intermediate analogue, 2-carboxyarabinitol 1,5-bisphosphate (2-CABP) has been determined at 2.4-A resolution. Compared with other Rubiscos, different amino residues bring the structural differences in active site, which are marked around the binding sites of P-2 phosphate of 2-CABP. Especially, side chains of His-327 and Arg-295 show the significant differences from those of spinach Rubisco. Moreover, the side chains of Asn-123 and His-294 which are reported to bind the substrate, ribulose 1,5-bisphosphate, form hydrogen bonds characteristic of Galdieria Rubisco. Small subunits of Galdieria Rubisco have more than 30 extra amino acid residues on the C terminus, which make up a hairpin-loop structure to form many interactions with the neighboring small subunits. When the structures of Galdieria and spinach Rubiscos are superimposed, the hairpin region of the neighboring small subunit in Galdieria enzyme and apical portion of insertion residues 52-63 characteristic of small subunits in higher plant enzymes are almost overlapped to each other.

Author: Stec, B.; Troxler, R. F.; Teeter, M. M.
Year: 1999
Title: Crystal structure of C-phycocyanin from Cyanidium caldarium provides a new perspective on phycobilisome assembly
Journal: Biophys J
Volume: 76
Issue: 6
Pages: 2912-2921
Date: Jun
Abstract: The crystal structure of the light-harvesting protein phycocyanin from the cyanobacterium Cyanidium caldarium with novel crystal packing has been solved at 1.65-A resolution. The structure has been refined to an R value of 18.3% with excellent backbone and side-chain stereochemical parameters. In crystals of phycocyanin used in this study, the hexamers are offset rather than aligned as in other phycocyanins that have been crystallized to date. Analysis of this crystal's unique packing leads to a proposal for phycobilisome assembly in vivo and for a more prominent role for chromophore beta-155. This new role assigned to chromophore beta-155 in phycocyanin sheds light on the numerical relationships among and function of external chromophores found in phycoerythrins and phycoerythrocyanins.

Author: Ohta, H.; Okumura, A.; Okuyama, S.; Akiyama, A.; Iwai, M.; Yoshihara, S.; Shen, J. R.; Kamo, M.; Enami, I.
Year: 1999
Title: Cloning, expression of the psbU gene, and functional studies of the recombinant 12-kDa protein of photosystem II from a red alga Cyanidium caldarium
Journal: Biochem Biophys Res Commun
Volume: 260
Issue: 1
Pages: 245-250
Date: Jun 24
Abstract: The encoding extrinsic 12-kDa protein of oxygen-evolving PS II complex from a red alga, Cyanidium caldarium, was cloned and sequenced by means of PCR and a rapid amplification of cDNA ends (RACE) procedure. The gene encodes a putative polypeptide of 154 amino acids with a calculated molecular mass of 16,714 Da. The full sequence of the protein includes two characteristic transit peptides, one for transfer across the chloroplast envelope and another for targeting into the thylakoid lumen. This indicates that the protein is encoded in the nuclear genome. The mature protein consists of 93 amino acids with a calculated molecular mass of 10,513 Da. The cloned gene was successfully expressed in Escherichia coli and the resulting protein was purified, reconstituted to CaCl2-washed PS II complex together with the other extrinsic proteins of 33 and 20 kDa and cyt c-550. The recombinant 12-kDa protein bound completely with the PSII complex, which resulted in a restoration of oxygen evolution equal to the level achieved by binding of the native 12-kDa protein.

Author: Oesterhelt, C.; Schnarrenberger, C.; Gross, W.
Year: 1999
Title: Characterization of a sugar/polyol uptake system in the red alga Galdieria sulphuraria
Journal: Europ. J. Phycol.
Volume: 34
Issue: 3
Pages: 271-277
Date: Aug
Abstract: The unicellular, acido- and thermophilic red alga Galdieria sulphuraria is unique in its ability to grow heterotrophically on at least 27 different sugars and polyols. The enzymatic machinery necessary for metabolizing this variety of compounds is constitutively expressed in the alga. The uptake system, however, has to be induced. From in vivo studies we conclude that the uptake system consists of several transporters with a partly overlapping substrate specificity. These transporters can be grouped into hexose, polyol and pentose transporters. The mode of induction depends on the substrate supplied for heterotrophic growth. When autotrophic cells were supplied with hexoses, hexose and polyol transporters were induced from the onset of heterotrophic conditions. Depletion of substrate in the medium triggered the induction of other transporters. Dulcitol, as well as other polyols and pentoses, led to a co- induction of all transporters as judged from induction and competition experiments. The heterotrophic capabilities of Galdieria are intriguing, because the natural habitat of the alga contains only traces of organic carbon. The substrates for heterotrophic growth apparently originate from decaying cells releasing hydrolysed cell material. Trace amounts of glucose were sufficient for the induction of sugar uptake in Galdieria. The co-induction of transporters obviously enables the cells in endolithic mats to import a wide spectrum of organic carbon in order to survive periods of light limitation.
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Author: Miyagishima, S.; Itoh, R.; Aita, S.; Kuroiwa, H.; Kuroiwa, T.
Year: 1999
Title: Isolation of dividing chloroplasts with intact plastid-dividing rings from a synchronous culture of the unicellular red alga cyanidioschyzon merolae
Journal: Planta
Volume: 209
Issue: 3
Pages: 371-375
Date: Sep
Abstract: In order to obtain a three-dimensional view of the plastid-dividing ring (PD ring) and promote the biochemical study of plastid division, we developed a procedure to isolate structurally intact dividing chloroplasts (rhodoplasts) possessing PD rings from a highly synchronized culture of the unicellular red alga Cyanidioschyzon merolae. The procedure consists of five steps. (1) The chloroplast division cycle is synchronized by light/dark cycles and treatment with 5-fluorodeoxyuridine. (2) The synchronized cells are treated with hypotonic solution. (3) The swollen cells are lysed in a French Pressure Cell. (4) The lysate is treated with DNase I. (5) The intact chloroplasts are separated by density-gradient centrifugation. The PD ring was visualized by fluorescence microscopy, after labeling the surface proteins of isolated chloroplasts with N-hydroxy-sulfo-succinimidyl biotin and detecting them with fluorescein isothiocyanate avidin. Scanning electron microscopy (SEM) showed that the outer envelopes and PD rings were conserved on the isolated dividing chloroplasts. These are the first fluorescence microscopic and SEM images of the PD ring and they clearly show PD rings encircling isolated dividing chloroplasts in three dimensions.

Author: Itoh, R.; Takano, H.; Ohta, N.; Miyagishima, S.; Kuroiwa, H.; Kuroiwa, T.
Year: 1999
Title: Two ftsH-family genes encoded in the nuclear and chloroplast genomes of the primitive red alga Cyanidioschyzon merolae
Journal: Plant Mol Biol
Volume: 41
Issue: 3
Pages: 321-337
Date: Oct
Abstract: The red algal chloroplast genome encodes an essential prokaryotic cell division gene, ftsH, which has never been found in the mitochondrial genome of any organism. To compare the conserved prokaryote-derived mechanism for mitochondrial division with that of chloroplasts, we cloned chloroplast- and nuclear-encoded ftsH genes from the primitive red alga Cyanidioschyzon merolae. The deduced amino-acid sequence of chloroplast ftsH (ftsHcp) consists of 603 amino acids and shows the highest similarity with algal-chloroplast and cyanobacterial FtsH. On the other hand, the nuclear-encoded ftsH (ftsH2) encodes a protein of 920 amino acids and has the highest similarity with two yeast mitochondrial FtsHs, Rca1p and Afg3p. Furthermore, the amino-terminal extension of FtsH2 appears to be an amphipathic alpha-helix, a characteristic mitochondrial targeting signal, suggesting that FtsH2 is a mitochondrial protein. Southern hybridization revealed that ftsH2 is a single gene located on chromosome III of the 17 C. merolae chromosomes. The level of expression of the 3.0 and 4.0 kb transcripts of this gene decreased in concert during the organelle division phase of a synchronized culture, indicating a cell-cycle-dependent manner of ftsH2 transcription, while northern hybridization did not detect ftsHcp transcripts. Nevertheless, reverse transcription-PCR and immunoblotting demonstrated for the first time that chloroplast-encoded ftsH is transcriptionally and translationally active. Overproduction of FtsHcp and FtsH2 in Escherichia coli disrupted cytokinesis and produced filamentous cells, but had no effect on the replication, segregation, or distribution of their nucleoids, as also occurs in ftsH-deficient E. coli. These observations suggest the possible involvement of both C. merolae FtsHs in organelle division.

Author: Heilmann, I.; Perera, I. Y.; Gross, W.; Boss, W. F.
Year: 1999
Title: Changes in phosphoinositide metabolism with days in culture affect signal transduction pathways in Galdieria sulphuraria
Journal: Plant Physiol
Volume: 119
Issue: 4
Pages: 1331-1339
Date: Apr
Abstract: The metabolism of phosphatidylinositol-4,5-bisphosphate (PIP,) changed during the culture period of the thermoacidophilic red alga Galdieria sulphuraria. Seven days after inoculation, the amount of PIP2 in the cells was 910 +/- 100 pmol g(-1) fresh weight; by 12 d, PIP2 levels increased to 1200 +/- 150 pmol g(- 1) fresh weight. In vitro assays indicated that phosphatidylinositol monophosphate (PIP) kinase specific activity increased from 75 to 230 pmol min(-1) mg(-1) protein between d 7 and 12. When G. sulphuraria cells were osmostimulated, transient increases of up to I-fold could be observed in inositol-1,4,5-trisphosphate (IP3) levels within 90 s, regardless of the age of the cells. In d-12 cells, the increase in IP3 was preceded by a transient increase of up to 5-fold in specific PIP kinase activity, whereas no such increase was detected after osmo-stimulation of d-7 cells. The increase in PIP kinase activity before IP3 signaling in d-12 cells indicates that there is an additional pathway for regulation of phosphoinositide metabolism after stimulation other than an initial activation of phospholipase C. Also, the rapid activation of PIP2 biosynthesis in cells with already- high PIP, levels suggests that the PIP2 present was not available for signal transduction. By comparing the response of the cells at d 7 and 12, we have identified two potentially distinct pools of PIP2.
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Author: Gross, W.
Year: 1999
Title: Revision of comparative traits for the acido- and thermophilic red algae Cyanidium and Galdieria.
Editor: Seckbach, J.
Book Title: Enigmatic Microorganisms and Life in Extreme Environments
City: Dordrecht
Publisher: Kluwer
Pages: 437-446

Author: Gross, W.; Lenze, D.; Nowitzki, U.; Weiske, J.; Schnarrenberger, C.
Year: 1999
Title: Characterization, cloning, and evolutionary history of the chloroplast and cytosolic class I aldolases of the red alga Galdieria sulphuraria
Journal: Gene
Volume: 230
Issue: 1
Pages: 7-14
Date: Apr 1
Abstract: Two fructose-1,6-bisphosphate aldolases from the acido- and thermophilic red alga Galdieria sulphuraria were purified to apparent homogeneity and N-terminally microsequenced. Both aldolases had similar biochemical properties such as Km (FBP) (5.6-5.8 microM) and molecular masses of the native enzymes (165kDa) as determined by size exclusion chromatography. The subunit size of the purified aldolases, as determined by SDS-PAGE, was 42kDa for both aldolases. The isoenzymes were not inhibited by EDTA or affected by cysteine or potassium ions, implying that they belong to the class I group of aldolases, while other red algae are known to have one class I and one class II aldolase inhibited by EDTA. cDNA clones of the cytosolic and plastidic aldolases were isolated and sequenced. The gene for the cytosolic isoenzyme contained a 303bp untranslated leader sequence, while the gene for the plastidic isoenzyme exhibited a transit sequence of 56 amino-acid residues. Both isoenzymes showed about 48% homology in the deduced amino-acid sequences. A gene tree relates both aldolases to the basis of early eukaryotic class I aldolases. The phylogenetic relationship to other aldolases, particularly to cyanobacterial class II aldolases, is discussed.

Author: Gross, W.; Oesterhelt, C.
Year: 1999
Title: Ecophysiological studies on the red alga Galdieria sulphuraria isolated from southwest Iceland
Journal: Plant Biology
Volume: 1
Issue: 6
Pages: 694-700
Date: Nov
Abstract: The acido- and thermophilic red alga, Galdieria sulphuraria, was isolated from three volcanic areas of the Reykjanes peninsula (southwest Iceland). These sites showed pH values of 1.5 to 3, low concentrations of dissolved organic carbon, and were apparently exclusively colonized by the red alga. No other eucaryotes were observed by light or electron microscopy. The isolated Galdieria strains grew heterotrophically on various sugars and polyols. At all three sites, Galdieria occupied terrestrial habitats. Extensive endolithic growth of the alga was only observed at one site where cell layers were found as deep as 3 cm within rocks of geyserite, a soft white siliceous mineral. Light is apparently insufficient for photosynthesis >10 mm below the stone surface. It is proposed that cells deep within the rode malts use of metabolites released by decaying cells in the surroundings. Cells isolated from these algal layers exhibited sugar uptake rates indicative for a low-level heterotrophic state. Therefore, the extraordinary heterotrophic capabilities of Galdieria seem to be especially important in endolithic habitats.
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Author: Cockell, C. S.; Rothschild, L. J.
Year: 1999
Title: The effects of UV radiation A and B on diurnal variation in photosynthesis in three taxonomically and ecologically diverse microbial mats
Journal: Photochem Photobiol
Volume: 69
Issue: 2
Pages: 203-210
Date: Feb
Abstract: Photosynthetic primary production, the basis of most global food chains, is inhibited by UV radiation. Evaluating UV inhibition is therefore important for assessing the role of natural levels of UV radiation in regulating ecosystem behavior as well as the potential impact of stratospheric ozone depletion on global ecosystems. As both photosynthesis and UV fluxes are subject to diurnal variations, we examined the diurnal variability of the effect of UV radiation on photosynthesis in three diverse algal mats. In one of the mats (Cyanidium caldarium) a small mean decrease in primary productivity over the whole day occurred when both UVA and UVB were screened out. In two of the mats (Lyngbya aestuarii and Zygogonium sp.) we found a mean increase in the total primary productivity over the day when UVB alone was screened and a further increase when UVA and UVB were both screened out. Variations in the effects of UV radiation were found at different times of the day. This diurnal variability may be because even under the same solar radiation flux, there are different factors that may control photosynthetic rate, including nutritional status and other physiological processes in the cell. The results show the importance of assessing the complete diurnal productivity. For some of the time points the increase in the mean was still within the standard deviations in primary productivity, illustrating the difficulty in dissecting UV effects from other natural variations.

Author: Oikawa, K.; Tanaka, K.; Takahashi, H.
Year: 1998
Title: Two types of differentially photo-regulated nuclear genes that encode sigma factors for chloroplast RNA polymerase in the red alga Cyanidium caldarium strain RK-1
Journal: Gene
Volume: 210
Issue: 2
Pages: 277-285
Date: Apr 14
Abstract: A nuclear gene, sigA, that encodes a sigma factor for chloroplast RNA polymerase has previously been identified and characterized in the primitive red alga Cyanidium caldarium strain RK-1. Southern hybridization analysis indicated the presence of two additional sigma factor genes, which have now been cloned and shown to encode virtually identical proteins that are homologous to eubacterial sigma factors. These genes, which are also present in the nuclear genome, have therefore been named sigB and sigC. The substantial sequence similarity of sigB and sigC to sigA of the same strain as well as to cyanobacterial principal sigma factors and other chloroplast sigma factors strongly suggests that the nuclear genome of C. caldarium contains three genes that encode two types of chloroplast sigma factors. Each of the three recombinant Sig proteins showed sigma factor activity in vitro when combined with the Escherichia coli RNA polymerase core enzyme. Northern blot analysis revealed that, whereas the overall abundance of sigA transcripts was not affected by light, the amount of sigB and sigC mRNAs was greater in the light than in the dark. Thus, multiple sigma factors appear to contribute to light-regulated gene expression in the chloroplast.

Author: Ohta, N.; Sato, N.; Kuroiwa, T.
Year: 1998
Title: Structure and organization of the mitochondrial genome of the unicellular red alga Cyanidioschyzon merolae deduced from the complete nucleotide sequence
Journal: Nucleic Acids Res
Volume: 26
Issue: 22
Pages: 5190-5298
Date: Nov 15
Abstract: The complete nucleotide sequence of the mitochondrial genome of a very primitive unicellular red alga, Cyanidioschyzon merolae , has been determined. The mitochondrial genome of C.merolae contains 34 genes for proteins including unidentified open reading frames (ORFs) (three subunits of cytochrome c oxidase, apocytochrome b protein, three subunits of F1F0-ATPase, seven subunits of NADH ubiquinone oxidoreductase, three subunits of succinate dehydrogenase, four proteins implicated in c-type cytochrome biogenesis, 11 ribosomal subunits and two unidentified open reading frames), three genes for rRNAs and 25 genes for tRNAs. The G+C content of this mitochondrial genome is 27.2%. The genes are encoded on both strands. The genome size is comparatively small for a plant mitochondrial genome (32 211 bp). The mitochondrial genome resembles those of plants in its gene content because it contains several ribosomal protein genes and ORFs shared by other plant mitochondrial genomes. In contrast, it resembles those of animals in the genome organization, because it has very short intergenic regions and no introns. The gene set in this mitochondrial genome is a subset of that of Reclinomonas americana , an amoeboid protozoan. The results suggest that plant mitochondria originate from the same ancestor as other mitochondria and that most genes were lost from the mitochondrial genome at a fairly early stage of the evolution of the plants.

Author: Lluisma, A. O.; Ragan, M. A.
Year: 1998
Title: Characterization of a galactose-1-phosphate uridylyltransferase gene from the marine red alga Gracilaria gracilis
Journal: Curr. Genet.
Volume: 34
Issue: 2
Pages: 112-119
Date: Aug
Abstract: The metabolism of D-galactose is a major feature of red-algal physiology. We have cloned and sequenced a gene from the red alga Gracilaria gracilis that encodes a key enzyme of D-galactose metabolism, galactose-l-phosphate uridylyltransferase (GALT). This gene, designated GgGALT1, is apparently devoid of introns. A potential TATA box, four potential CAAT boxes, and a repeated sequence occur in the 5'-flanking region. The predicted 369-aa peptide shares significant sequence similarity with GALTs from other organisms (human, 47%; Saccharomyces cerevisiae, 49%; Solanum tuberosum, 49%). Southern-hybridization analysis reveals two related, but apparently not identical, GALT genes in the nuclear genome of G. gracilis. Sequence analysis indicates that the GgGALT1 enzyme lacks a rubredoxin "knuckle" motif, which in bacterial and fungal GALTs is involved in binding zinc. An open reading frame encoding a potential peptidyl tRNA hydrolase occurs 179 bp downstream from the GgGALT1 gene.
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Author: Kuroiwa, T.; Kuroiwa, H.; Sakai, A.; Takahashi, H.; Toda, K.; Itoh, R.
Year: 1998
Title: The division apparatus of plastids and mitochondria
Journal: Int Rev Cytol
Volume: 181
Pages: 1-41
Abstract: Mitochondria and plastids in eukaryotic cells contain distinct genomes and multiply in the cytoplasm by binary division of preexisting organelles. Mitochondrial and plastid nuclei are easily visualized as compartments in the matrix of organelles by high-resolution fluorescence microscopy and by immunoelectron microscopy using anti-DNA antibodies. Plastid and mitochondrial division can be clearly separated into two main events: division of the organelle nuclei, and then division of the rest of the organelles, the process of organellokinesis (mitochondriokinesis and plastidokinesis). The mechanical apparatus that regulates organellokinesis has remained undetermined. In 1986, the plastid-dividing apparatus (PD ring) for plastidokinesis was first identified by us in the primitive red alga Cyanidium caldarium RK-1. The PD ring is located in the cytoplasm outside the organelle envelope at the constricted isthmus of dividing organelles and has subsequently been found in all eukaryotic plants examined. We were also the first to identify the mitochondrion-dividing apparatus (MD ring) for mitochondriokinesis in the unicellular red alga Cyanidioschyzon merolae in 1993. Eukaryotic cell division is therefore controlled by at least three dividing apparata (rings), a contractile ring, an MD ring, and a PD ring, while bacterial division is controlled by a single bacterial contractile FtsZ ring. The aims of this review are to present the fine structure, process of formation, and contraction of the organelle-dividing apparatus, focusing on evolutionary conservation and diversion from the bacterial contractile ring.

Author: Gross, W.; Kuver, J.; Tischendorf, G.; Bouchaala, N.; Busch, W.
Year: 1998
Title: Cryptoendolithic growth of the red alga Galdieria sulphuraria in volcanic areas
Journal: Eur. J. Phycol.
Volume: 33
Issue: 1
Pages: 25-31
Date: Feb
Abstract: The habitat of the acido- and thermophilic red algae Galdieria sulphuraria and Cyanidium caldarium was examined in acidic hot sulphur springs in the vicinity of Naples (Italy). These species grew on soil and rocks, but a large part of the populations was cryptoendolithic. The endolithic algal layer (1-3 mm in thickness) was covered by amorphous silica (1-2 mm in thickness) containing traces of hydrotroilite (FeS. nH(2)O) and elemental sulphur. Organotrophic bacteria and fungi were not found in the algal layer. Light penetration measurements showed that 0.1-1% of the sunlight reached the upper part of the algal layer. Thus, low-light-adapted algae should be able to perform some photosynthesis in this endolithic habitat. Under conditions where light is even more limited, e.g. in winter or after darkening of the covering layer, many of the cells might not survive. Aqueous extracts of these algae are excellent growth substrates for Galdieria sulphuraria. Therefore, we propose that compounds released from dead cells in the endolithic layer are used by the surrounding Galdieria cells for heterotrophic metabolism. This would increase their chance of surviving prolonged periods under detrimental conditions.
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Author: Enami, I.; Kikuchi, S.; Fukuda, T.; Ohta, H.; Shen, J. R.
Year: 1998
Title: Binding and functional properties of four extrinsic proteins of photosystem II from a red alga, Cyanidium caldarium, as studied by release-reconstitution experiments
Journal: Biochemistry
Volume: 37
Issue: 9
Pages: 2787-2793
Date: Mar 3
Abstract: Photosystem II (PSII) from a red alga, Cyanidium caldarium, contains four extrinsic proteins of 33, 20, and 12 kDa and cytochrome (cyt)c550 [Enami, I., et al., (1995) Biochim. Biophys. Acta 1232, 208-216]. The binding and functional properties of these four proteins in the red algal PSII were studied by release-reconstitution experiments. Of the four components, the 33 kDa protein binds to PSII completely by itself, and the 20 kDa protein binds to a level 61% of that in native PSII in the absence of other proteins. In contrast, cyt c550 and the 12 kDa protein cannot bind to PSII efficiently by themselves; their effective binding requires the other three extrinsic proteins. In particular, a strong interaction was observed between cyt c550 and the 12 kDa protein, and a weaker interaction was observed between cyt c550 and the 20 kDa protein. While binding of the 33 kDa protein alone or cyt c550 and the 12 kDa protein in the presence of the 33 and/or the 20 kDa protein generally enhanced oxygen evolution, binding of the 20 kDa protein did not. Oxygen evolution was strongly dependent on Ca2+ and Cl- in the absence of cyt c550 and the 12 kDa protein, suggesting that these two proteins have functions similar to those of the 23 and 17 kDa proteins in higher plant PSII. From these results, we propose that the unique 20 kDa extrinsic protein found only in the red algal PSII functions in maintaining the proper binding of cyt c550 and the 12 kDa protein but is not involved directly in oxygen evolution. The binding and functional properties of these four proteins were compared with those of the three extrinsic proteins found in cyanobacterial and higher plant PSII in an evolutionary point of view.

Author: Disch, A.; Schwender, J.; Muller, C.; Lichtenthaler, H. K.; Rohmer, M.
Year: 1998
Title: Distribution of the mevalonate and glyceraldehyde phosphate/pyruvate pathways for isoprenoid biosynthesis in unicellular algae and the cyanobacterium Synechocystis PCC 6714
Journal: Biochem J
Volume: 333 ( Pt 2)
Pages: 381-388
Date: Jul 15
Abstract: Isopentenyl diphosphate, the universal isoprenoid precursor, can be produced by two different biosynthetic routes: either via the acetate/mevalonate (MVA) pathway, or via the more recently identified MVA-independent glyceraldehyde phosphate/pyruvate pathway. These two pathways are easily differentiated by incorporation of [1-13C]glucose and analysis of the resulting labelling patterns found in the isoprenoids. This method was successfully applied to several unicellular algae raised under heterotrophic growth conditions and allowed for the identification of the pathways that were utilized for isoprenoid biosynthesis. All isoprenoids examined (sterols, phytol, carotenoids) of the green algae Chlorella fusca and Chlamydomonas reinhardtii were synthesized via the GAP/pyruvate pathway, as in another previously investigated green alga, Scenedesmus obliquus, which was also shown in this study to synthesize ubiquinone by the same MVA-independent route. In the red alga Cyanidium caldarium and in the Chrysophyte Ochromonas danica a clear dichotomy was observed: as in higher plants, sterols were formed via the MVA route, whereas chloroplast isoprenoids (phytol in Cy. caldarium and O. danica and beta-carotene in O. danica) were synthesized via the GAP/pyruvate route. In contrast, the Euglenophyte Euglena gracilis synthesized ergosterol, as well as phytol, via the acetate/MVA route. Similar feeding experiments were performed with the cyanobacterium Synechocystis PCC 6714 using [1-13C]- and [6-13C]-glucose. The two isoprenoids examined, phytol and beta-carotene, were shown to have the typical labelling pattern derived from the GAP/pyruvate route.

Author: Uemura, K.; Anwaruzzaman; Miyachi, S.; Yokota, A.
Year: 1997
Title: Ribulose-1,5-bisphosphate carboxylase/oxygenase from thermophilic red algae with a strong specificity for CO2 fixation
Journal: Biochem Biophys Res Commun
Volume: 233
Issue: 2
Pages: 568-571
Date: Apr 17
Abstract: Strongly carboxylase-specific ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) was found in Galdieria partita and Cyanidium caldarium (Cyanidiophyceae). The relative specificity, VcKo/VoKc, of Galdieria and Cyanidium RuBisCO was 238 and 222, respectively; 2.4 to 2.5-fold that of higher plant RuBisCOs. The apparent Km of RuBisCO from the thermophilic red algae for CO2 was 6 to 7 microM and the smallest of the values reported so far for other RuBisCOs. The pre-rhodophyte Porphiridium purpureum, which lives at moderate temperatures, had RuBisCO with the relative specificity value of 144. A large difference (5.2 kcal x mol(-1)) in the activation energies between the carboxylase and oxygenase activities in Galdieria RuBisCO was a cause of the strong specificity for the carboxylase activity.

Author: Turner, L.; Houghton, J. D.; Brown, S. B.
Year: 1997
Title: Purification and identification of apophycocyanin alpha and beta subunits from soluble protein extracts of the red alga Cyanidium caldarium. Light exposure is not a prerequisite for biosynthesis of the protein moiety of this photosynthetic accessory pigment
Journal: Planta
Volume: 201
Issue: 1
Pages: 78-83
Abstract: Much controversy exists as to the level at which light exerts control over the biosynthesis of the photosynthetic apparatus in higher plants and other organisms. The eukaryotic red alga Cyanidium caldarium, like higher plants, undergoes light induction of chlorophyll synthesis. In addition to chlorophyll a the alga also synthesises the linear tetrapyrrole phycocyanobilin, which is combined with alpha or beta apobiliproteins to form phycocyanin, the major light-harvesting pigment in this organism. We have previously shown that the tetrapyrrole precursor 5-aminolaevulinic acid (ALA) can substitute for light in inducing the biosynthesis of the phycocyanobilin moiety of this protein. We have also described the appearance of a protein of similar isoelectric point and molecular weight to phycocyanin in ALA-fed cells (Turner et al., 1992, Plant Physiol Biochem 30: 309-314). We now report on the protein's immunological and sequence identity with phycocyanin alpha and beta subunits, and provide further evidence that bilin-apoprotein ligation is light dependent.

Author: Tan, S.; Cunningham, F. X., Jr.; Gantt, E.
Year: 1997
Title: LhcaR1 of the red alga Porphyridium cruentum encodes a polypeptide of the LHCI complex with seven potential chlorophyll a-binding residues that are conserved in most LHCs
Journal: Plant Mol Biol
Volume: 33
Issue: 1
Pages: 157-167
Date: Jan
Abstract: The accessory light-harvesting polypeptides associated with photosystem I (LHCI) in Porphyridium cruentum bind chlorophyll a, zeaxanthin and beta-carotene. A cDNA library of P. cruentum was screened with an antiserum specific to the LHCI polypeptides, and an 0.9 kb fragment was identified as coding for an LHCI polypeptide. This cDNA, which we named LhcaR1, has an open reading frame encoding 222 amino acid residues including a putative transit peptide of 28 amino acids. Hydropathy analysis suggests that there are three transmembrane helices in the mature polypeptide. Each of the amino acid residues that bind chlorophyll (six residues) and serve in stabilizing the helices in higher-plant LHCs are conserved in helices 1 and 3 of P. cruentum LhcaR1. The N-terminal flanking regions of these two helices also show high sequence conservation with other LHCs. Helix 2 contains a seventh putative chlorophyll-binding site, but resembles helix 2 of higher-plant LHCs to a lesser degree. A sequence motif of 11 residues found near the N-terminus and in each of the three helices suggests the possibility that the red algal LhcaR1 derives from a gene duplication. Polypeptides of the expected molecular weight in six other red algae (Achrochaetium, Bangia, Callithamnion, Cyanidium, Polysiphonia, Spermothamnion) were recognized by the antiserum to P. cruentum LHCI, indicating a wide distribution of LHCI in rhodophytes.

Author: Stein, R.; Gross, W.; Schnarrenberger, C.
Year: 1997
Title: Characterization of a xylitol dehydrogenase and a D-arabitol dehydrogenase from the thermo- and acidophilic red alga Galdieria sulphuraria
Journal: Planta
Volume: 202
Issue: 4
Pages: 487-493
Date: Aug
Abstract: Galdieria sulphuraria (Galdieri) Merola can grow heterotrophically on at least ten different polyols. We investigated their metabolic path to glycolysis/gluconeogenesis and identified two NAD-dependent polyol dehydrogenases. Activity of other enzymes metabolizing mannitol or sorbitol could not be detected. The two dehydrogenases had a broad substrate specificity and were termed xylitol dehydrogenase (EC 1.1.1.14; substrate specificity: xylitol > D-sorbitol > D- mannitol > L-arabitol) and D-arabitol dehydrogenase (EC 1.1.1.11; substrate specificity: D-arabitol > L-fucitol > D- mannitol > D-threitol) according to the substrate with the lowest K-m value. The xylitol dehydrogenase was stable during purification. In contrast, the D-arabitol dehydrogenase was thermolabile and depended on divalent ions for stability and activity, preferentially Mn2+ and Ni2+. The molecular mass of the xylitol dehydrogenase was estimated to be 295 kDa by size- exclusion chromatography and 220 kDa by rate-sedimentation centrifugation. The D-arabitol dehydrogenase had a molecular mass of 105 kDa as determined by rate-sedimentation centrifugation. The specific activity of both enzymes increased about fourfold when cells were transferred from autotrophic to heterotrophic conditions regardless of whether sugars or polyols were supplied as substrates. The significance of polyol metabolism in Galdieria sulphuraria with regard to the natural habitat of the alga is discussed.
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Author: Stein, R.; Schnarrenberger, C.; Gross, W.
Year: 1997
Title: Myo-inositol dehydrogenase from the acido- and thermophilic red alga Galdieria sulphuraria
Journal: Phytochemistry
Volume: 46
Issue: 1
Pages: 17-20
Date: Sep
Abstract: A NAD-dependent myo-inositol dehydrogenase (EC 1.1.1.18) has been purified from the acido- and thermophilic red alga Galdieria sulphuraria. This enzyme catalyses the reversible oxidation of myo-inositol to scyllo-inosose (2-keto-inositol). The activity with scyllo-inosose and NADH was a 75-times higher than with myo-inositol and NAD. At pH 8.0 the equilibrium of the reaction strongly favours the production of myoinositol. The K-m values for myo-inositol and scyllo-inosose were 430 mM and 1.3 mM, respectively. The dehydrogenase is specific for myo-inositol and scyllo-inosose. The enzyme was purified about 205-fold to apparent homogeneity with a specific activity of 63 mu kat mg protein(-1) with scyllo-inosose as substrate. The M-r of the subunits was 42 000 and of the native enzyme ca 189 000. (C) 1997 Elsevier Science Ltd. All rights reserved.
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Author: Schwender, J.; Zeidler, J.; Groner, R.; Muller, C.; Focke, M.; Braun, S.; Lichtenthaler, F. W.; Lichtenthaler, H. K.
Year: 1997
Title: Incorporation of 1-deoxy-D-xylulose into isoprene and phytol by higher plants and algae
Journal: FEBS Lett
Volume: 414
Issue: 1
Pages: 129-134
Date: Sep 1
Abstract: In further substantiating the novel mevalonate-independent pathway for isoprenoid biosynthesis, which generates isopentenyl diphosphate (IPP) via 1-deoxy-D-xylulose-5-phosphate, labeling experiments with 1-[2H(1)]deoxy-D-xylulose were performed with various higher plants and algae: efficient incorporation was observed into isoprene emitted by Populus, Chelidonium, and Salix, into the phytol moiety of chlorophylls in a red alga (Cyanidium), in two green algae (Scenedesmus, Chlamydomonas), and a higher plant (Lemna). By contrast, 13C-mevalonate applied was incorporated into isoprene and phytol to a much lower extent or not at all. This demonstrates that this '1-deoxy-D-xylulose-5-phosphate pathway' for biosynthesis of plastidic isoprenoids is widely distributed in photosynthetic organisms.

Author: Ohta, N.; Sato, N.; Nozaki, H.; Kuroiwa, T.
Year: 1997
Title: Analysis of the cluster of ribosomal protein genes in the plastid genome of a unicellular red alga Cyanidioschyzon merolae: translocation of the str cluster as an early event in the rhodophyte-chromophyte lineage of plastid evolution
Journal: J Mol Evol
Volume: 45
Issue: 6
Pages: 688-695
Date: Dec
Abstract: The nucleotide sequence of a cluster of ribosomal protein genes in the plastid genome of a unicellular red alga, Cyanidioschyzon merolae, which has been supposed to be the most primitive alga, was determined. The phylogenetic tree inferred from the amino acid sequence of ribosomal proteins of two rhodophytes, a chromophyte, a glaucophyte, two chlorophytes (land plants), a cyanobacterium, and three eubacteria suggested a close relationship between the cyanobacterium Synechocystis PCC6803 and the plastids of various species in the kingdom Plantae, which is consistent with the hypothesis of the endosymbiotic origin of plastids. In this tree, the two species of rhodophytes were grouped with the chromophyte, and the glaucophyte was grouped with the chlorophytes. Analysis of the organization of the genes encoding the ribosomal proteins suggested that the translocation of the str cluster occurred early in the lineage of rhodophytes and chromophytes after these groups had been separated from chlorophytes and glaucophytes.

Author: Ohta, H.; Shirakawa, H.; Uchida, K.; Yoshida, M.; Matuo, Y.; Enami, I.
Year: 1997
Title: Cloning and sequencing of the gene encoding the plasma membrane H(+)-ATPase from an acidophilic red alga, Cyanidium caldarium
Journal: Biochim Biophys Acta
Volume: 1319
Issue: 1
Pages: 9-13
Date: Mar 28
Abstract: A cDNA containing an open reading frame encoding the putative plasma membrane H(+)-ATPase in an acidophilic red alga, Cyanidium caldarium, was cloned and sequenced by means of PCR and Southern hybridization based on homologous sequences of P-type ATPases found in other organisms. The cloned cDNA is 3300 bp in length, containing a 2865 bp open reading frame encoding a polypeptide of 955 amino acids which has a predicted molecular mass of 105,371. The deduced amino acid sequence was found to be more homologous to those of P-type H(+)-ATPases from higher plants than that from the green alga Dunaliella bioculata.

Author: Oesterhelt, C.; Schnarrenberger, C.; Gross, W.
Year: 1997
Title: The reaction mechanism of phosphomannomutase in plants
Journal: Febs Letters
Volume: 401
Issue: 1
Pages: 35-37
Date: Jan 13
Abstract: The enzyme phosphomannomutase catalyzes the interconversion of mannose-1-phosphate (Man-1-P) and mannose-6-phosphate (Man-6- P). In mammalian cells the enzyme has to be activated by transfer of a phosphate group from a sugar-1.6-P-2 (Guha, S.K. and Rose, Z.B. (1985) Arch. Biochem. Biophys. 243, 168). In contrast, in the red alga Galdieria sulphraria the co-substrate (Man-1.6-P-2 or Glc-1.6-P-2) is converted to the corresponding sugar monophosphate while the substrate is converted to the sugar bisphosphate in each reaction cycle. Evidence is presented that the same reaction mechanism occurs in spinach and yeast.
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Author: Heilmann, I.; Schnarrenberger, C.; Gross, W.
Year: 1997
Title: Mannose metabolizing enzymes from the red alga Galdieria sulphuraria
Journal: Phytochemistry
Volume: 45
Issue: 5
Pages: 903-906
Date: Jul
Abstract: The unicellular thermo-acidophilic rhodophyte Galdieria sulphuraria is capable of growing at high rates on D-mannose, a sugar toxic to many higher plants. Mannose is introduced into metabolism through an ATP-dependent fructokinase which phosphorylates fructose (K-m = 0.21 mM) as well as mannose (K-m = 0.48 mM) but not glucose; The product, mannose-6-phosphate, is converted to fructose-6-phosphate by a mannose-6-phosphate isomerase (K-m = 1.2 mM). The fructokinase was purified by chromatography on DEAE-Fractogel and hydroxylapatite. The enzyme is a homodimer with an M-r of 75 000. The mannose-6- phosphate isomerase was purified by PEG precipitation and affinity chromatography on Affinity-Gel Blue A. The enzyme is a monomer with an M-r of 48 000. The pathway of mannose utilization in G. sulphuraria strongly resembles the reactions of mannose non-sensitive higher plants, while plants with mannose sensitivity lack activity of mannose-6-phosphate isomerase. © 1997 Elsevier Science Ltd. All rights reserved.
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Author: Heilmann, I.; Gross, W.; Boss, W. F.
Year: 1997
Title: Polyphosphoinositide metabolism of Galdieria sulphuraria
Journal: Plant Physiol
Volume: 114
Issue: 3
Pages: 1390-1390
Date: Jul
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Author: Gross, W.; Seipold, P.; Schnarrenberger, C.
Year: 1997
Title: Characterization and Purification of an Aldose Reductase from the Acidophilic and Thermophilic Red Alga Galdieria sulphuraria
Journal: Plant Physiol
Volume: 114
Issue: 1
Pages: 231-236
Date: May
Abstract: The acidophilic and thermophilic red alga Galdieria sulphuraria is able to grow heterotrophically on at least six different pentoses. These pentoses are reduced in the cell to pentiols by an NADP-dependent aldose reductase. The pentiols are then introduced into the oxidative pentose phosphate pathway via NAD-dependent polyol dehydrogenases and pentulokinases. The aldose reductase was purified 130-fold to apparent homogeneity by column chromatography. The enzyme is a homodimer of about 80 kD, as estimated by size-exclusion chromatography and from the sedimentation behavior. The Michaelis constant values for D-xylose (27 mM), D-ribose (29 mM), D-lyxose (30 mM), and D-arabinose (38 mM) were about three to five times lower than for the L-forms of the sugars. The activity of the enzyme with hexoses, deoxysugars, and sugar phosphates was only about 5 to 10% of the rate with pentoses. In the reverse reaction the activity was low and only detectable with pentiols. No activity was measured with NAD(H) as the cosubstrate in either direction.

Author: Vogel, H.; Fischer, S.; Valentin, K.
Year: 1996
Title: A model for the evolution of the plastid sec apparatus inferred from secY gene phylogeny
Journal: Plant Mol Biol
Volume: 32
Issue: 4
Pages: 685-692
Date: Nov
Abstract: Plastids possess a bacteria-like sec apparatus that is involved in protein import into the thylakoid lumen. We have analyzed one of the genes essential for this process, secY. A secY gene from the unicellular red alga Cyanidium caldarium was found to be transcriptionally active, demonstrating for the first time that secY is functional in a plastid. Unlike the situation seen in bacteria the C. caldarium gene is transcribed monocistronically, despite the fact that it is part of a large ribosomal gene cluster that resembles bacterial spc operons. A molecular phylogeny is presented for 8 plastid-encoded secY genes, four of which have not been published yet. In this analysis plastid secY genes fall into two classes. One of these, comprising of genes from multicellular red algae and Cryptophyta, clusters in a neighbour-joining tree with a cyanobacterial counterpart. Separated from the aforesaid are secY genes from Chromophyta, Glaucocystophyta and a unicellular red alga. All plastid and cyanobacterial sequences are located on the same branch, separated from bacterial homologues. We postulate that the two classes of secY genes are paralogous, i.e. their gene products are involved in different protein translocation processes. Based on this assumption a model for the evolution of the plastid sec apparatus is presented.

Author: Viehmann, S.; Richard, O.; Boyen, C.; Zetsche, K.
Year: 1996
Title: Genes for two subunits of succinate dehydrogenase form a cluster on the mitochondrial genome of Rhodophyta
Journal: Curr Genet
Volume: 29
Issue: 2
Pages: 199-201
Date: Jan
Abstract: Mitochondrial DNA from the unicellular rhodophyte Cyanidium caldarium RK-1 and the multicellular Chondrus crispus were isolated, cloned, and sequenced. Two genes, sdhB and sdhC, that encode subunits of the succinate dehydrogenase, were identified by similarity. These genes form a cluster (sdhCB) in both red algae.

Author: Tanaka, K.; Oikawa, K.; Ohta, N.; Kuroiwa, H.; Kuroiwa, T.; Takahashi, H.
Year: 1996
Title: Nuclear encoding of a chloroplast RNA polymerase sigma subunit in a red alga
Journal: Science
Volume: 272
Issue: 5270
Pages: 1932-1935
Date: Jun 28
Abstract: A chloroplast RNA polymerase sigma factor is encoded by a nuclear gene, sigA, in the red alga Cyanidium caldarium RK-1. The encoded protein functions as an RNA polymerase sigma factor in vitro and it is localized to the chloroplast in vivo. SigA shows high sequence similarity to the sigma factors of cyanobacteria, which is indicative of the ancestral endosymbiotic event and subsequent transfer of the sigA gene to the nuclear genome.

Author: Shibata, N.; Yamamoto, H.; Inoue, T.; Uemura, K.; Yokota, A.; Kai, Y.
Year: 1996
Title: Crystallization and preliminary crystallographic studies of ribulose 1,5-bisphosphate carboxylase/oxygenase from a red alga, Galdieria partita, with a high specificity factor
Journal: J Biochem (Tokyo)
Volume: 120
Issue: 6
Pages: 1064-1066
Date: Dec
Abstract: Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) from a red alga, Galdieria partita, has been crystallized by the hanging drop vapor diffusion method. Two forms (Forms I and II) of crystals were obtained under distinct conditions. The Form I crystal belongs to monoclinic space group C2 with cell dimensions of a = 190.2, b = 140.0, c = 189.0 A, and beta = 102.6 degrees, and diffracts up to 3.0 A resolution. Diffraction from the Form II crystal was too weak to determine crystal data.

Author: Prosselkov, P. V.; Gross, W.; Igamberdiev, A. U.; Schnarrenberger, C.
Year: 1996
Title: Purification and characterization of UDP-D-galactose 4-epimerase from the red alga Galdieria sulphuraria
Journal: Physiol Plant
Volume: 98
Issue: 4
Pages: 753-758
Date: Dec
Abstract: UDP-D-galactose 4-epimerase of the unicellular red alga Galdieria sulphuraria has been purified to apparent electrophoretic homogeneity by chromatography on DEAE- Fractogel, hydroxylapatite and by affinity chromatography on Dyematrex Orange. The holoenzyme is a homodimer with an apparent molecular mass of 83 and 76 kDa as determined by gelfiltration and by sucrose gradient centrifugation, respectively. The size of the subunits was 42 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The 4-epimerase from G. sulphuraria does not require external NAD for activity, unlike the enzyme from some other organisms, and inhibition by NADH was not observed. The apparent K-m, for UDP-D-galactose was 64 mu M. The pH optimum was at 8 and the apparent equilibrium constant for UDP-Glc/UDP-Gal was 3.5. The enzyme in crude as well as in purified samples was unusually stable and was not inactivated even on incubation at 46 degrees C for several hours.
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Author: Oesterhelt, C.; Schnarrenberger, C.; Gross, W.
Year: 1996
Title: Phosphomannomutase and phosphoglucomutase in the red alga Galdieria sulphuraria
Journal: Plant Sci.
Volume: 121
Issue: 1
Pages: 19-27
Date: Nov 29
Abstract: The enzymes phosphoglucomutase (PGM) and phosphomannomutase (PMM) from the red alga Galdieria sulphuraria in were separated from each other on hydroxylapatite. PGM is specific for glucose phosphates as substrates. PMM on the other hand is bifunctional for glucose phosphates and mannose phosphates. Both substrates are competitive. These findings are similar to characteristics of PGM and PMM from other organisms, although PGM is usually regarded as a multifunctional enzyme. The PGM has a K-M of 25 mu M for glc-1-P. The equilibrium constant is 3.7, favouring the production of glc-6-P. The holoenzyme is a dimer with a subunit size of 40 kDa. The PMM uses glucose phosphates and mannose phosphates at about the same rate with a K-M(glc-1-P) of 10 mu M and a K-M(man-1-P) of 50 mu M For both substrates the equilibrium constant is around 1. The PMM-holoenzyme also is a dimer with a subunit size of 40 kDa. Copyright © 1996 Elsevier Science Ireland Ltd.
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Author: Liu, B.; Troxler, R. F.
Year: 1996
Title: Molecular characterization of a positively photoregulated nuclear gene for a chloroplast RNA polymerase sigma factor in Cyanidium caldarium
Journal: Proc Natl Acad Sci U S A
Volume: 93
Issue: 8
Pages: 3313-3318
Date: Apr 16
Abstract: We have cloned the gene for a putative chloroplast RNA polymerase sigma factor from the unicellular rhodophyte Cyanidium caldarium. This gene contains an open reading frame encoding a protein of 609 amino acids with domains highly homologous to all four conserved regions found in bacterial and cyanobacterial sigma 70-type subunits. When Southern blots of genomic DNA were hybridized to the "rpoD box" oligonucleotide probe, up to six hybridizing hands were observed. Transcripts of the sigma factor gene were undetectable in RNA from dark-grown cells but were abundant in the poly(A)+ fraction of RNA from illuminated cells. The sigma factor gene was expressed in Escherichia coli, and antibodies against the expressed sigma factor fusion protein cross-reacted with a 55-kDa protein in partially purified chloroplast RNA polymerase. Antibodies directed against a cyanobacterial RNA polymerase sigma factor also cross-reacted with a 55-kDa protein in the same enzyme preparation. Immunoprecipitation experiments showed that this enzyme preparation contains proteins with the same molecular weights as the alpha, beta, beta', and beta" subunits of chloroplast RNA polymerase in higher plants. This study identifies a gene for a plastid RNA polymerase sigma factor and indicates that there may be a family of nuclear-encoded sigma factors that recognize promoters in subsets of plastid genes and regulate differential gene expression at the transcriptional level.

Author: Ziegler, K.; Hauska, G.; Nelson, N.
Year: 1995
Title: Cyanidium caldarium genes encoding subunits A and B of V-ATPase
Journal: Biochim Biophys Acta
Volume: 1230
Issue: 3
Pages: 202-206
Date: Jun 30
Abstract: The genes encoding subunits A and B of V-ATPase in Cyanidium caldarium were cloned and sequenced. While the gene encoding subunit A is not interrupted by introns, the gene encoding subunit B contains seven introns ranging from 36 to 60 nucleotides.

Author: Troxler, R. F.; Yan, Y.; Jiang, J. W.; Liu, B.
Year: 1995
Title: Nucleotide sequence and expression of the genes for the alpha and beta subunits of phycocyanin in Cyanidium caldarium
Journal: Plant Physiol
Volume: 107
Issue: 3
Pages: 985-994
Date: Mar
Abstract: The nucleotide sequence of the plastid-encoded operon containing genes for the alpha (cpcA) and beta (cpcB) subunits of phycocyanin in the unicellular red alga Cyanidium caldarium is described. cpcB is located 5' to cpcA and the two genes are separated by a 102-bp spacer region. The transcription start site of cpcBA was mapped to 80 bp upstream of the ATG initiation codon of cpcB. Promoter-like elements similar to the -10 (TATAAT) and -35 (TTGACA) consensus promoters in bacteria were found 6 and 31 bp upstream of the transcription initiation site. Northern blotting revealed an abundant 1.3-kb cpcBA transcript in illuminated cells, but this transcript was undetectable in dark-grown cells. Expression levels of cpcBA in cells incubated with 10(-6) M heme in the dark were similar to those in cells illuminated for 24 h. Cells illuminated with 150 microM gabaculine (an inhibitor of delta-aminolevulinate synthesis) or 10 mM levulinic acid (an inhibitor of delta-aminolevulinate dehydrase) lacked detectable cpcBA transcripts. In cells illuminated with 200 microM N-methyl-mesoporphyrin IX (an inhibitor of ferrocheletase), inhibition of cpcBA expression and phycocyanin synthesis was similar. These results provide strong evidence that light induction of the cpcBA operon is dependent on synthesis of heme.

Author: Takahashi, H.; Takano, H.; Yokoyama, A.; Hara, Y.; Kawano, S.; Toh-e, A.; Kuroiwa, T.
Year: 1995
Title: Isolation, characterization and chromosomal mapping of an actin gene from the primitive red alga Cyanidioschyzon merolae
Journal: Curr Genet
Volume: 28
Issue: 5
Pages: 484-490
Date: Oct
Abstract: Based on the results of cytological studies, it has been assumed that Cyanidioschyzon merolae does not contain actin genes. However, Southern hybridization of C. merolae cell-nuclear DNA with a yeast actin-gene probe has been suggested the presence of an actin gene in the C. merolae genome. In the present study, an actin gene was isolated from a C. merolae genomic library using a yeast actin-gene probe. The C. merolae actin gene has no intron. The predicted actin is composed of 377 amino acids and has an estimated molecular mass of 42 003 Da. Southern hybridization indicated that the C. merolae genome contains only one actin gene. This gene is transcribed at a size of 2.4 kb. When Southern hybridization was performed with C. merolae chromosomes separated by pulsed-field gel electrophoresis, a band appeared on unseparated chromosomes XI and XII. A phylogenetic tree based on known eucaryote actin-gene sequences revealed that C. merolae diverged after the division of Protozoa, but before the division of Fungi, Animalia and Chlorophyta.

Author: Suzuki, K.; Kawazu, T.; Mita, T.; Takahashi, H.; Itoh, R.; Toda, K.; Kuroiwa, T.
Year: 1995
Title: Cytokinesis by a contractile ring in the primitive red alga Cyanidium caldarium RK-1
Journal: Eur J Cell Biol
Volume: 67
Issue: 2
Pages: 170-178
Date: Jun
Abstract: To better understand the mechanism of cytokinesis in eukaryotes, the behavior of the contractile ring in the two unicellular primitive red algae Cyanidioschyzon merolae and Cyanidium caldarium RK-1, which have the smallest genome size among eukaryotes, was examined by fluorescein isothiocyanate (FITC)-phalloidin fluorescence microscopy, fluorometry using a video-intensified microscope photoncounting system, transmission electron microscopy and immunoblotting techniques. Cells in each alga contained one nucleus, one mitochondrion and one chloroplast, which were aligned in that order. During cytokinesis in C. merolae, a contractile ring was not observed by fluorescence microscopy or by transmission electron microscopy. In contrast, in C. caldarium RK-1, a contractile ring appeared at the equatorial region of the dividing cells and began to contract from the side of the chloroplast. During contraction of this ring, the total fluorescent intensities due to FITC-phalloidin remained constant. Electron microscopy revealed outer and inner bands approximately 80 nm wide and 9 nm thick which ran parallel to each other just beneath the cell membrane. These bands were visible at the equator of the cell just before the initiation of cytokinesis and constricted from the pole of the chloroplast. Both bands increased in width as cleavage progressed. The inner ring consisted of a bundle of approximately 20 actin-like filaments which were arranged as a raft. In the outer ring, such fine filaments were not visible. It seems likely that the bundle of filaments, known as the contractile ring, is composed of two different elements: an inner band of actin filaments and an outer band of unknown materials.(ABSTRACT TRUNCATED AT 250 WORDS)

Author: Rhie, G.; Beale, S. I.
Year: 1995
Title: Phycobilin biosynthesis: reductant requirements and product identification for heme oxygenase from Cyanidium caldarium
Journal: Arch Biochem Biophys
Volume: 320
Issue: 1
Pages: 182-194
Date: Jun 20
Abstract: Algal heme oxygenase is a soluble enzyme from Cyanidium caldarium that catalyzes the first committed step of phycobilin biosynthesis by converting protoheme to biliverdin IX alpha. Although the physiological substrate (protoheme) of algal heme oxygenase is identical to that of microsomal heme oxygenase, which catalyzes heme catabolism in animals, the two enzyme systems differ in several respects including the nature of the required reductants and solubility of the enzymes. Addition of the strong Fe3+ ion chelators, desferrioxamine and Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid), greatly increased the yield of solvent-extracted bilin product. The effect of the Fe3+ chelators was approximately equal whether they were added during or after the enzyme incubation. Postincubation treatment of the enzyme reaction mixture with strong acid also greatly increased the product yield. Addition of desferrioxamine to the reaction mixture after the incubation was terminated caused the appearance of an absorption spectrum, indicating an increase in the concentration of free bilin product. Acid and Fe3+ chelators are known to cause dissociation of Fe(III)-bilin complexes. These results indicate that the in vitro enzymic reaction product of algal heme oxygenase is a nonenzyme-bound Fe(III)-biliverdin IX alpha complex that is poorly extracted and/or quantitated unless it is first dissociated. Algal heme oxygenase required the simultaneous presence of both reduced ferredoxin and a second reductant such as ascorbate for activity. The requirement for L-ascorbate could be substituted by Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) or D-ascorbate, but not by dehydroascorbate or dithiothreitol. Heme oxygenase was purified over 200-fold from C. caldarium by differential (NH4)2SO4 precipitation and serial column chromatography over reactive blue 2-Sepharose, DEAE-cellulose, Sephadex G-75, and ferredoxin-Sepharose.

Author: Gross, W.; Schnarrenberger, C.
Year: 1995
Title: Heterotrophic Growth of 2 Strains of the Acido-Thermophilic Red Alga Galdieria sulphuraria
Journal: Plant Cell Physiol.
Volume: 36
Issue: 4
Pages: 633-638
Date: Jun
Abstract: The acido- and thermophilic red alga Galdieria sulphuraria (Galdieri) Merola grows under mixo- and heterotrophic conditions on 27 different sugars and sugar alcohols as sole carbon source. We separated two strains from an isolate originally collected at Mt. Lawu (Indonesia). These strains are indistinguishable in growth and pigmentation under autotrophic conditions. However, under heterotrophic conditions, strain 074 W lost most of its pigments whereas strain 074 G stayed green on all substrates tested. Strain 074 G had the highest pigment content when grown on sugar alcohols. Usually the alga exhibited a short lag-phase followed by logarithmic growth. However, when transferred from auto- to heterotrophic conditions a lag-period of about 45 days was observed with the sugar alcohol dulcitol. Similarly, long lag-periods were also noticed for strain 074 G grown on D-mannitol and for strain 074 W grown on D-ribose. The length of the lag-phase is a function of the length of the previous culture under autotrophic conditions. This enormous versatility in the heterotrophic growth of Galdieria sulphuraria presents an ideal system to study the metabolism of rare sugars and sugar alcohols.
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Author: Gross, W.; Schnarrenberger, C.
Year: 1995
Title: Purification and Characterization of a Galactose-1-Phosphate-UDP-Glucose Uridyltransferase from the Red Alga Galdieria sulphuraria
Journal: Eur J Biochem
Volume: 234
Issue: 1
Pages: 258-263
Date: Nov 15
Abstract: The galactose-1-phosphate uridyltransferase of the red alga Galdieria sulphuraria has been purified about 1800-fold to a final specific activity of approximately 140 U/mg protein. The purification involved chromatography on DEAE-Fractogel, hydroxyapatite, decyl-agarose, and DEAE-Tentacle gel. After SDS/PAGE, the enzyme preparation showed only one protein band of 42 kDa. The enzyme is a homodimer with a molecular mass of 82 kDa as estimated from the sedimentation velocity or 60 kDa as estimated by gel filtration. It has a broad pH optimum between pH 7 and pH 9. The apparent K-m values for the forward and backward reactions are K-m(Glc1P) = 105 mu M, K-m(UDP- galactose) = 30 mu M, K-m(Gal1P) = 400 mu M, and K-m(UDP-Glc) = 20 mu M The activation energy of the reaction is 45 kJ mol(-1). The enzyme is specific for the galactose 1-phosphate to UDP- galactose interconversion in the Leloir pathway while the alternate enzyme for the Isselbacher pathway, UDP-galactose pyrophosphorylase, could not be detected in G. sulphuraria.
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Author: Enami, I.; Murayama, H.; Ohta, H.; Kamo, M.; Nakazato, K.; Shen, J. R.
Year: 1995
Title: Isolation and characterization of a Photosystem II complex from the red alga Cyanidium caldarium: association of cytochrome c-550 and a 12 kDa protein with the complex
Journal: Biochim Biophys Acta
Volume: 1232
Issue: 3
Pages: 208-216
Date: Dec 12
Abstract: A Photosystem II (PS II) complex was purified from an acidophilic as well as a thermophilic red alga, Cyanidium caldarium. The purified PS II complex was essentially devoid of phycobiliproteins and other contaminating components, and showed a high oxygen-evolving activity of 2375 mumol O2/mg Chl per h using phenyl-p-benzoquinone as the electron acceptor. The expression of this high activity did not require addition of exogenous Ca2+, although EDTA reduced the activity by 40%. This effect of EDTA can be reversed not only by Ca2+ but also by Mg2+; a similar Mg2+ effect has been observed in purified cyanobacterial PS II but not in higher plant PS II. Immunoblotting analysis indicated the presence of major intrinsic polypeptides commonly found in PS II from cyanobacteria and higher plants as well as the extrinsic 33 kDa protein. Antibodies against the extrinsic 23 and 17 kDa proteins of higher plant PS II, however, did not crossreact with any polypeptides in the purified PS II, indicating the absence of these proteins in the red alga. In contrast, two other extrinsic proteins of 17 and 12 kDa were present in the red algal PS II; they were released by 1 M Tris or Urea/NaCl treatment but not by 1 M NaCl. The 17 kDa polypeptide was identified to be cytochrome c-550 from heme-staining, immunoblot analysis and N-terminal amino acid sequencing, and the 12 kDa protein was found to be homologous to the 12 kDa extrinsic protein of cyanobacterial PS II from its N-terminal sequence. These results indicate that PS II from the red alga is closely related to PS II from cyanobacteria rather than to that from higher plants, and that the replacement of PS II extrinsic cytochrome c-550 and the 12 kDa protein by the extrinsic 23 and 17 kDa proteins occurred during evolution from red algae to green algae and higher plants.

Author: Troxler, R. F.; Zhang, F.; Hu, J.; Bogorad, L.
Year: 1994
Title: Evidence that sigma factors are components of chloroplast RNA polymerase
Journal: Plant Physiol
Volume: 104
Issue: 2
Pages: 753-759
Date: Feb
Abstract: Plastid genes are transcribed by DNA-dependent RNA polymerase(s), which have been incompletely characterized and have been examined in a limited number of species. Plastid genomes contain rpoA, rpoB, rpoC1, and rpoC2 coding for alpha, beta, beta', and beta" RNA polymerase subunits that are homologous to the alpha, beta, and beta' subunits that constitute the core moiety of RNA polymerase in bacteria. However, genes with homology to sigma subunits in bacteria have not been found in plastid genomes. An antibody directed against the principal sigma subunit of RNA polymerase from the cyanobacterium Anabaena sp. PCC 7120 was used to probe western blots of purified chloroplast RNA polymerase from maize, rice, Chlamydomonas reinhardtii, and Cyanidium caldarium. Chloroplast RNA polymerase from maize and rice contained an immunoreactive 64-kD protein. Chloroplast RNA polymerase from C. reinhardtii contained immunoreactive 100- and 82-kD proteins, and chloroplast RNA polymerase from C. caldarium contained an immunoreactive 32-kD protein. The elution profile of enzyme activity of both algal chloroplast RNA polymerases coeluted from DEAE with the respective immunoreactive proteins, indicating that they are components of the enzyme. These results provide immunological evidence for sigma-like factors in chloroplast RNA polymerase in higher plants and algae.

Author: Seckbach, J.
Year: 1994
Title: Evolutionary pathways and enigmatic algae: Cyanidium caldarium (Rhodophyta) and related cells.
Editor: Seckbach, J.
Book Title: Developments in Hydrobiology
City: Dordrecht
Publisher: Kluwer Academic Publishers
Volume: 91
Pages: 349

Author: Seckbach, J.
Year: 1994
Title: The First Eukaryotic Cells - Acid Hot-Spring Algae
Journal: J. Biol. Phys.
Volume: 20
Issue: 1-4
Pages: 335-345
Abstract: The Cyanidiophyceae members (PreRhodophyta) may serve as a transitional algal group bridging the cyanobacteria and the unicellular Rhodophyta. This thermoacidic algal group is composed of three genera containing several species. We suggested placing these algae in progressively evolutionary steps: (Cyanidioschyzon --> Cyanidium --> Galdieria). This evolutional ladder is based upon various areas of research like biochemistry, amount of nuclear genome and shape of chloroplast nucleoid, ultrastructure and ecological aspects. The first alga - Cyanidioschyzon - is the cornerstone of this succession; it shows mixed features between cyanobacterium and archaebacteria (Thermoplasma-like cell). It demonstrates simple eukaryotic cellular features and has the smallest amount of nuclear and chloroplast DNA. The intermediate alga in this line, Cyanidium, is also a simple cell, but shows more progressive characterizations than the Cyanidioschyzon. The third taxon, Galdieria, is already very close to the unicellular rhodophytes (red algae) and indicates typical advanced eukaryotic characterization. We propose that Cyanidioschyzon (considered to be the simplest eukaryote) may have evolved from an association between Thermoplasma-like archaebacterium and a thermophilic cyanobacterium. Autogenous (non-symbiotic) compartmental steps may have taken place from Cyanidioschyzon to Cyanidium and then to Galdieria, and from this alga (group) towards the other unicellular red algae.
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Author: Rothschild, L. J.
Year: 1994
Title: Elevated CO2: impact on diurnal patterns of photosynthesis in natural microbial ecosystems
Journal: Adv Space Res
Volume: 14
Issue: 11
Pages: 285-289
Abstract: Algae, including blue-green algae (cyanobacteria), are the major source of fixed carbon in many aquatic ecosystems. Previous work has shown that photosynthetic carbon fixation is often enhanced in the presence of additional carbon dioxide (CO2). This study was undertaken to determine if this CO2 fertilization effect extended to microbial mats, and, if so, at what times during the day might the addition of CO2 affect carbon fixation. Four microbial mats from diverse environments were selected, including mats from a hypersaline pond (area 5, Exportadora de Sal, Mexico), the marine intertidal (Lyngbya, Laguna Ojo de Liebre, Mexico), an acidic hotspring (Cyanidium, Nymph Creek, Yellowstone National Park), and an acidic stream at ambient temperature (Zygogonium, Yellowstone National Park). Carbon fixation in the absence of additional CO2 essentially followed the rising and falling sunlight levels, except that during the middle of the day there was a short dip in carbon fixation rates. The addition of CO2 profoundly enhanced carbon fixation rates during the daylight hours, including during the midday dip. Therefore, it is unlikely that the midday dip was due to photoinhibition. Surprisingly, enhancement of carbon fixation was often greatest in the early morning or late afternoon, times when carbon fixation would be most likely to be light limited.

Author: Rhie, G.; Beale, S. I.
Year: 1994
Title: Regulation of heme oxygenase activity in Cyanidium caldarium by light, glucose, and phycobilin precursors
Journal: J Biol Chem
Volume: 269
Issue: 13
Pages: 9620-9626
Date: Apr 1
Abstract: Cyanobacteria, red algae, and cryptophytes contain phycobiliproteins which function as photosynthetic light-harvesting pigments. The chromophores of phycobiliproteins are phycobilins, open-chain tetrapyrroles that are synthesized from protoheme. The first step of phycobilin formation is the conversion of protoheme to biliverdin IX alpha in a reaction that is catalyzed by heme oxygenase. In the unicellular red alga, Cyanidium caldarium, light is required for the accumulation of phycobiliproteins. It has been reported previously that the synthesis of the apoprotein components of allophycocyanin and phycocyanin is induced by light in C. caldarium, that the phycobilin precursors, delta-aminolevulinic acid (ALA), protoporphyrin IX, and protoheme can substitute for light, and that the regulation is exerted at the level of mRNA synthesis. We have determined that a key enzyme of phycobilin formation is induced by light in C. caldarium. Extractable heme oxygenase activity is low in dark-grown cells, and it increases approximately 6-fold during the first 24 h after the cells are illuminated. After 24 h, the activity decreases to a level approximately equal to the initial activity. Heme oxygenase is induced in unilluminated cells by administration of ALA. D-Glucose, which is known to inhibit phycocyanin accumulation in C. caldarium, inhibits the induction of heme oxygenase by light or ALA. Induction of heme oxygenase by light or ALA is blocked by cycloheximide, an inhibitor of cytoplasmic protein synthesis, but not by chloramphenicol, an inhibitor of chloroplast protein synthesis. Rifampicin, an inhibitor of algal chloroplast RNA synthesis, and gabaculine, a competitive inhibitor of ALA biosynthesis, block the induction of heme oxygenase by light but not by ALA. These results indicate that heme oxygenase in C. caldarium is induced by phycobilin precursors. The induction by light and the repression of the induction by D-glucose are probably indirect effects mediated by the effects of light and D-glucose on phycobilin precursor formation. The results also indicate that heme oxygenase is encoded by a nuclear gene and is synthesized on cytoplasmic ribosomes.

Author: Ohta, N.; Sato, N.; Kawano, S.; Kuroiwa, T.
Year: 1994
Title: The trpA gene on the plastid genome of Cyanidium caldarium strain RK-1
Journal: Curr Genet
Volume: 25
Issue: 4
Pages: 357-361
Date: Apr
Abstract: The trpA gene (for the alpha subunit of tryptophan synthase) was found on the plastid genome of the "primitive" unicellular red alga Cyanidium caldarium strain RK-1. This is the first example of an actively-transcribed gene for tryptophan synthase encoded on a plastid genome. In contrast to trpA, trpB (the gene for the beta subunit of tryptophan synthase) was encoded in the cell nucleus. Considering the primitive characteristics of C. caldarium, trpB must have been lost from the plastid genome before trpA.

Author: Ohta, N.; Kawano, S.; Kuroiwa, T.
Year: 1994
Title: Physical map of the plastid genome of the unicellular red alga Cyanidium caldarium strain RK-1
Journal: Curr Genet
Volume: 26
Issue: 2
Pages: 136-138
Date: Aug
Abstract: The physical map of the plasmid genome of the unicellular red alga Cyanidium caldarium strain RK-1 was constructed. The 150-kbp genome was circular and had an inverted repeated region (IR) which contained the genes for 16 s and 23 s ribosomal RNAs, as is usually seen in most plastid genomes. Since C. caldarium is a very "primitive" alga, the results suggest that the ancestral cyanobacteria lost most of its genome as an endosymbiont comparatively early in the process of plastid formation. After that, several genes seem to have been lost from plastid genomes, step by step, during the course of evolution.

Author: Moreira, D.; Lopezarchilla, A. I.; Amils, R.; Marin, I.
Year: 1994
Title: Characterization of 2 New Thermoacidophilic Microalgae - Genome Organization and Comparison with Galdieria sulphuraria
Journal: FEMS Microbiol Lett
Volume: 122
Issue: 1-2
Pages: 109-114
Date: Sep 15
Abstract: Thermoacidophilic algae (Cyanidiaceae) constitute a taxonomic group with interesting phylogenetic and ecological implications. In this report, we have classified three thermoacidophilic microalgal isolates from Rio Tinto (Spain) using a combination of classical analysis of phenotypic features and the characterization of their electrophoretically determined karyotypes by means of pulsed-field gel electrophoresis. Using this technique, we have been able to demonstrate that thermoacidophilic algae genomes have the smallest genomes of all photosynthetic eukaryotes studied so far. In addition, we show that two of these Rio Tinto isolates may constitute new species within the genus Galdieria.
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Author: Liu, B.; Troxler, R. F.
Year: 1994
Title: The allophycocyanin alpha subunit gene from Cyanidium caldarium
Journal: Plant Physiol
Volume: 104
Issue: 3
Pages: 1085-1086
Date: Mar

Author: Beale, S. I.
Year: 1994
Title: Biosynthesis of open-chain tetrapyrroles in plants, algae, and cyanobacteria
Journal: Ciba Found Symp
Volume: 180
Pages: 156-168; discussion 168-171
Abstract: Phycobilins are open-chain tetrapyrroles of plants and algae which act as the chromophores of phycobiliproteins where they function as light energy-harvesting pigments. Phytochromobilin, another open-chain tetrapyrrole, is the chromophore of phytochrome, which functions as a light-sensing pigment in plant development. These open-chain tetrapyrroles are biosynthetically derived from protohaem. Enzyme reactions that convert protohaem to biliverdin IX alpha, and biliverdin IX alpha to phycocyanobilin, have been detected and characterized in extracts of the unicellular rhodophyte Cyanidium caldarium. Algal haem oxygenase and algal biliverdin-IX alpha reductase are both soluble enzymes that use electrons derived from reduced ferredoxin. Biochemical intermediates in the conversion of biliverdin IX alpha to (3E)-phycocyanobilin were identified as 15, 16-dihydrobiliverdin IX alpha, (3Z)-phycoerythrobilin and (3Z)-phycocyanobilin. Separate enzymes catalyse the two two-electron reduction steps in the conversion of biliverdin IX alpha to (3Z)-phycoerythrobilin. Z-to-E isomerization of the phycobilin ethylidine group is catalysed by an enzyme that requires glutathione for activity. Protein-bound phycoerythrobilin can be chemically converted to phytochromobilin which can then be released from the protein by methanolysis. This procedure was used to produce phytochromobilin in quantities sufficient to allow its chemical characterization and use in phytochrome reconstitution experiments. The results indicate that (2R,3E)-phytochromobilin spontaneously condenses with recombinant oat apophytochrome to form photoreversible holoprotein that is spectrally identical to native phytochrome.

Author: Liu, B.; Troxler, R. F.
Year: 1993
Title: A Cyanidium caldarium allophycocyanin beta subunit gene
Journal: Plant Physiol
Volume: 103
Issue: 1
Pages: 293-294
Date: Sep

Author: Kostrzewa, M.; Zetsche, K.
Year: 1993
Title: Organization of plastid-encoded ATPase genes and flanking regions including homologues of infB and tsf in the thermophilic red alga Galdieria sulphuraria
Journal: Plant Mol Biol
Volume: 23
Issue: 1
Pages: 67-76
Date: Oct
Abstract: We have cloned and sequenced the plastid ATPase operons (atp1 and atp2) and flanking regions from the unicellular red alga Galdieria sulphuraria (Cyanidium caldarium). Six genes (5 atpI, H, G, F, D and A 3) are linked in atp1 encoding ATPase subunits a, c, b, b, delta and alpha, respectively. The atpF gene does not contain an intron and overlaps atpD by 1 bp. As in the genome of chloroplasts from land plants, the cluster is located downstream of rps2, but between this gene and atp1 we found the gene for the prokaryotic translation elongation factor TS. Downstream of atpA, we detected two open reading frames, one encoding a putative transport protein. The genes atpB and atpE, encoding ATPase subunits beta and epsilon, respectively, are linked in atp2, separated by a 2 bp spacer. Upstream of atpB, an uninterrupted orf167 was detected which is homologous to an intron-containing open reading frame in land plant chloroplasts. This orf167 is preceded on the opposite DNA strand by a homologue to initiation factor 2 in prokaryotes. The arrangement of atp1 and atp2 is the same as observed in the multicellular red alga Antithamnion sp., indicating a conserved genome arrangement in the red algal plastid genome. Differences compared to green chloroplast genomes suggest a large phylogenetic distance between red algae and green plants, while similarities in arrangement and sequence to chromophytic ATPase operons support a red algal origin of chlorophyll a/c-containing plastids or alternatively point to a common prokaryotic endosymbiont.

Author: Jakab, G.; Kis, M.; Pollak, T.; Solymosy, F.
Year: 1993
Title: Nucleotide sequence of cytoplasmic 5S rRNA from a eukaryotic thermophilic unicellular alga, Cyanidium caldarium
Journal: Nucleic Acids Res
Volume: 21
Issue: 11
Pages: 2770
Date: Jun 11

Author: Valentin, K.; Maid, U.; Emich, A.; Zetsche, K.
Year: 1992
Title: Organization and expression of a phycobiliprotein gene cluster from the unicellular red alga Cyanidium caldarium
Journal: Plant Mol Biol
Volume: 20
Issue: 2
Pages: 267-276
Date: Oct
Abstract: We have sequenced a plastid gene cluster from the unicellular red alga Cyanidium caldarium which is located downstream from the psbA gene and contains, in the following order, genes for a beta-allophycocyanin-like protein (apcB'), a putative 9.5 kDa allophycocyanin linker protein (apcL9.5) and a putative 29 kDa phycocyanin linker protein (cpcL29). The apcB' and apcL9.5 genes are organized in the form of an operon. The cpcL29 gene is transcribed monocistronically from the opposite strand of DNA. Both transcription units are probably terminated at a 25 bp inverted repeat 3 and 5 bp downstream of the stop codons of the apcL9.5 and cpcL29 genes, respectively. The levels of both transcripts are greatly reduced in the dark as is the psbA transcript. Downstream from the phycobiliprotein gene cluster two open reading frames (ORFs) were found which are homologous to ORFs from plastid DNAs and cyanelle DNA of Cyanophora paradoxa. Sequence homologies between genes analysed in this study and corresponding genes from cyanobacteria, chlorophytic plastids and cyanelles point to a large phylogenetic distance between the plastids of Cyanidium and cyanobacteria and other plastid types.

Author: Suzuki, K.; Ohta, N.; Kuroiwa, T.
Year: 1992
Title: Isolation of the Cell-Nuclear, Mitochondrial, and Chloroplast DNA from the Ultra-Small Eukaryote Cyanidioschyzon merolae
Journal: Protoplasma
Volume: 171
Issue: 1-2
Pages: 80-84
Abstract: The amounts of cell-nuclear DNA (cl-DNA), mitochondrial DNA (mt-DNA) and chloroplast DNA (cp-DNA) in Cyanidioschyzon merolae were estimated by using a video-intensified microscope (VIM) system. C. merolae had the smallest amount of cell- nuclear DNA among eukaryotes. The results show that a cell-nucleus, a mitochondrion and a chloroplast contain an average 8.0 x 10(3) kbp, 1.6 x 10(3) kbp, and 5.0 x 10(3) kbp, respectively. To confirm these results, cl-DNA, mt-DNA, and cp- DNA were isolated from cells by density centrifugation on Hoechst 33258/CsCl after density centrifugation on ethidium bromide/CsCl. The amounts of cl-DNA, mt-DNA, and cp-DNA obtained from the bands supported the data shown by the VIM- system. The cytochemical and biochemical characteristics were compared with those of Cyanidium caldarium RK-1 and C. caldarium Forma A. The p values of cl-DNA and cpDNA of C. merolae were about 1.716 and 1.709, respectively. The order in density was different from that of C. caldarium Forma A but very similar to that of C. caldarium RK-1. However, the restriction patterns of cp-DNA in C. merolae differed from those of C. caldarium RK-1.
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Author: Seckbach, J.; Gonzales, E.; Wainwright, I. M.; Gross, W.
Year: 1992
Title: Peroxisomal Function in the Cyanidiophyceae (Rhodophyta) - a Discussion of Phylogenetic-Relationships and the Evolution of Microbodies (Peroxisomes)
Journal: Nova Hedwigia
Volume: 55
Issue: 1-2
Pages: 99-109
Date: Aug
Abstract: A brief review and discussion of the available evidence for microbodies (peroxisomes) and their enzymes in Cyanidioschyzon merolae, Cyanidium caldarium and Galdieria sulphuraria (Cyanidiophyceae, Rhodophyta) is presented. All Cyanidiophyceae express a pattern of peroxisomal enzymes which is anomalous when compared to that observed in other algal or higher plant cells. These thermoacidophilic algae exhibit activities of catalase, glycolate oxidase and glutamate-glyoxylate aminotransferase. Other peroxisomal enzymes in this microalgal group are either in the cytosol (e.g., serine-glyoxylate aminotransferase and hydroxypyruvate reductase) or in the mitochondrion (e.g., fatty acid beta-oxidation). The evidence suggests a pattern of subcellular complexity among the members of the Cyanidiophyceae that may provide some insights into the evolution and metabolic role(s) of peroxisomes.
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Author: Rhie, G.; Beale, S. I.
Year: 1992
Title: Biosynthesis of phycobilins. Ferredoxin-supported nadph-independent heme oxygenase and phycobilin-forming activities from Cyanidium caldarium
Journal: J Biol Chem
Volume: 267
Issue: 23
Pages: 16088-16093
Date: Aug 15
Abstract: The unicellular red alga, Cyanidium caldarium, synthesizes phycocyanobilin from protoheme via biliverdin IX alpha. In vitro transformation of protoheme to biliverdin IX alpha and biliverdin IX alpha to phycobilins were previously shown to require NADPH, ferredoxin, and ferredoxin-NADP+ reductase, as well as specific heme oxygenase and phycobilin formation enzymes. The role of NADPH in these reactions was investigated in this study. The C. caldarium enzymatic activities that catalyze biliverdin IX alpha formation from protoheme, and phycobilin formation from biliverdin IX alpha, were partially purified by differential (NH4)2SO4 precipitation. The enzyme fractions, when supplemented with a light-driven ferredoxin-reducing photosystem I fraction derived from spinach leaves, catalyzed light-dependent transformation of protoheme to biliverdin IX alpha and biliverdin IX alpha to phycobilins, with or without the addition of NADPH and ferredoxin-NADP+ reductase. In the dark, neither reaction occurred unless NADPH and ferredoxin-NADP+ reductase were supplied. These results indicate that the only role of NADPH in both reactions of phycobilin biosynthesis, in vitro, is to reduce ferredoxin via ferredoxin-NADP+ reductase and that reduced ferredoxin can directly supply the electrons needed to drive both steps in the transformation of protoheme to phycocyanobilin.

Author: Ohta, N.; Nagashima, H.; Kawano, S.; Kuroiwa, T.
Year: 1992
Title: Isolation of the chloroplast DNA and the sequence of the trnk gene from Cyanidium caldarium strain RK-1
Journal: Plant & Cell Physiol.
Volume: 33
Pages: 657-661

Author: Maid, U.; Steinmuller, R.; Zetsche, K.
Year: 1992
Title: Structure and expression of a plastid-encoded groEL homologous heat-shock gene in a thermophilic unicellular red alga
Journal: Curr Genet
Volume: 21
Issue: 6
Pages: 521-525
Date: May
Abstract: A gene homologous to the E. coli groEL locus was identified on the plastid genome of the unicellular red alga Cyanidium caldarium strain 14-1-1 (synonym: Galdieria sulphuraria). The complete nucleotide sequence was determined and compared to bacterial- and nuclear-encoded counterparts of higher plants. At the amino-acid level the C. caldarium gene shows 70% homology to the corresponding gene of the cyanobacterium Synechococcus and 52% homology to nuclear-encoded counterparts of higher plants, respectively. Northern and Western blot experiments were used to investigate the dependence of the transcript- and protein-level on culture temperature and heat shock.

Author: Maid, U.; Zetsche, K.
Year: 1992
Title: A 16 kb small single-copy region separates the plastid DNA inverted repeat of the unicellular red alga Cyanidium caldarium: physical mapping of the IR-flanking regions and nucleotide sequences of the psbD-psbC, rps16, 5S rRNA and rpl21 genes
Journal: Plant Mol Biol
Volume: 19
Issue: 6
Pages: 1001-1010
Date: Sep
Abstract: The four inverted repeat (IR) flanking regions of the Cyanidium caldarium plastid DNA were cloned. Southern blotting, transcript and sequence analyses of the border regions revealed the psbD-psbC operon and the rps16 gene within the large single-copy region upstream of the 16S rDNA gene and the rpl21 gene downstream of the 5S rDNA within the 16 kb small single-copy region. The size of the IR is ca. 5 kb. The nucleotide sequences of the psbD-psbC, rps16, rpl21 and 5S rRNA genes with the corresponding alignments and physical maps of the regions are presented. Northern analysis revealed a less complex psbD-psbC transcription pattern than has been found in higher plants. Comparisons to other red algal data point to structural diversity within red algal plastid DNA.

Author: Elela, S. A.; Nazar, R. N.
Year: 1992
Title: Extended secondary structure as a basis of increased RNA stability in a thermophilic alga Cyanidium caldarium
Journal: Biochim Biophys Acta
Volume: 1130
Issue: 3
Pages: 339-342
Date: Apr 6
Abstract: To identify important structural features in the intergenic sequences of ribosomal DNAs, the nucleotide sequence of the 18-25S rRNA intergenic region was determined in a thermophilic alga, Cyanidium caldarium. Although the mature 5.8S RNA is more stable to thermal denaturation, sequence comparisons reveal a longer molecule with a surprisingly low G/C nucleotide composition. Estimates of the structure further indicate that, unlike other thermophilic examples, thermostability in this organism results, at least in part, from an extended secondary structure.

Author: Yurina, N.P.; Karakashev, G.V.; Karapetyan, N.V.; Odintsova, M.S.
Year: 1991
Title: Composition and Biosynthesis of Thylakoid Membrane Polypeptides in the Red Alga Cyanidium caldarium - Comparison with the Thylakoid Polypeptide Composition of Higher Plants and Cyanobacteria
Journal: Photosynthesis Research
Volume: 30
Pages: 15-23

Author: Seckbach, J.
Year: 1991
Title: Systematic Problems with Cyanidium caldarium and Galdieria sulphuraria and Their Implications for Molecular-Biology Studies
Journal: J. Phycol.
Volume: 27
Issue: 6
Pages: 794-796
Date: Dec
Go to ISI:A1991GY88100019

Author: Seckbach, J.
Year: 1991
Title: Systematic problems with Cyanidium caldarium

Author: Maid, U.; Zetsche, K.
Year: 1991
Title: Structural features of the plastid ribosomal RNA operons of two red algae: Antithamnion sp. and Cyanidium caldarium
Journal: Plant Mol Biol
Volume: 16
Issue: 4
Pages: 537-546
Date: Apr
Abstract: The nucleotide sequences of the plastid 16S rDNA of the multicellular red alga Antithamnion sp. and the 16S rDNA/23S rDNA intergenic spacers of the plastid DNAs of the unicellular red alga Cyanidium caldarium and of Antithamnion sp. were determined. Sequence comparisons support the idea of a polyphyletic origin of the red algal and the higher-plant chloroplasts. Both spacer regions include the unsplit tRNA(Ile)(GAU) and tRNA(Ala)(UGC) genes and so the plastids of both algae form a homogeneous group with those of chromophytic algae and Cyanophora paradoxa characterized by 'small-sized' rDNA spacers in contrast to green algae and higher plants. Nevertheless, remarkable sequence differences within the rRNA and the tRNA genes give the plastids of Cyanidium caldarium a rather isolated position.

Author: Beale, S. I.; Cornejo, J.
Year: 1991
Title: Biosynthesis of phycobilins. Ferredoxin-mediated reduction of biliverdin catalyzed by extracts of Cyanidium caldarium
Journal: J Biol Chem
Volume: 266
Issue: 33
Pages: 22328-22332
Date: Nov 25
Abstract: Cell-free extract of the unicellular rhodophyte, Cyanidium caldarium catalyzes enzymatic reduction of biliverdin IX alpha to phycocyanobilin, the chromophore of the light-harvesting phycobiliprotein, phycocyanin. The enzyme activity is soluble, and the required reductant is NADPH. The extract has been separated into three protein fractions, all of which are required to reconstitute biliverdin reduction. One fraction contains ferredoxin, which was identified by its absorption spectrum. This fraction could be replaced with commercial ferredoxin derived from spinach or the red alga, Porphyra umbilicalis. The second protein fraction contains ferredoxin-NADP+ reductase, which was identified by the ability to catalyze ferredoxin-dependent reduction of cytochrome c in the presence of NADPH. This fraction could be replaced with commercial spinach ferredoxin-NADP+ reductase. These two components appear to be identical to previously described components of the algal heme oxygenase system that catalyzes biliverdin IX alpha formation from protoheme in C. caldarium extracts. The third protein fraction, in the presence of the first two (or their commercial counterparts) plus NADPH, catalyzes the reduction of biliverdin IX alpha to phycocyanobilin. The results indicate that the transformation of biliverdin to phycocyanobilin catalyzed by C. caldarium extracts is a ferredoxin-linked reduction process. The results also suggest the possibility that heme oxygenation and biliverdin reduction may occur in C. caldarium on associated enzyme systems.

Author: Beale, S. I.; Cornejo, J.
Year: 1991
Title: Biosynthesis of phycobilins. 3(Z)-phycoerythrobilin and 3(Z)-phycocyanobilin are intermediates in the formation of 3(E)-phycocyanobilin from biliverdin IX alpha
Journal: J Biol Chem
Volume: 266
Issue: 33
Pages: 22333-22340
Date: Nov 25
Abstract: An enzyme extract from the phycocyanin-containing unicellular rhodophyte, Cyanidium caldarium, reductively transforms biliverdin IX alpha to phycocyanobilin, the chromophore of phycocyanin, in the presence of NADPH. Unpurified cell extract forms both 3(E)-phycocyanobilin, which is identical to the major pigment that is released from phycocyanin by methanolysis, and 3(Z)-phycocyanobilin, which is obtained as a minor methanolysis product. After removal of low molecular weight material from the cell extract, only 3(Z)-phycocyanobilin is formed. 3(E)-Phycocyanobilin formation from biliverdin IX alpha, and the ability to isomerize 3(Z)-phycocyanobilin to 3(E)-phycocyanobilin, are reconstituted by the addition of glutathione to the incubation mixture. Partially purified protein fractions derived from the initial enzyme extract form 3(Z)-phycocyanobilin plus two additional, violet colored bilins, upon incubation with NADPH and biliverdin IX alpha. Further purified protein fractions produce only the violet colored bilins from biliverdin IX alpha. One of these bilins was identified as 3(Z)-phycoerythrobilin by comparative spectrophotometry, reverse-phase high pressure liquid chromatography, and 1H NMR spectroscopy. A C. caldarium protein fraction catalyzes the conversion of 3(Z)-phycoerythrobilin to 3(Z)-phycocyanobilin. This fraction also catalyzes the conversion of 3(E)-phycoerythrobilin to 3(E)-phycocyanobilin. The conversion of phycoerythrobilins to phycocyanobilins requires neither biliverdin nor NADPH. The synthesis of phycoerythrobilin and its conversion to phycocyanobilin by extracts of C. caldarium, a species that does not contain phycoerythrin, indicates that phycoerythrobilin is a biosynthetic precursor to phycocyanobilin. The enzymatic conversion of the ethylidine group from the Z to the E configuration suggests that the E-isomer is the precursor to the protein-bound chromophore.

Author: Beale, S. I.; Cornejo, J.
Year: 1991
Title: Biosynthesis of phycobilins. 15,16-Dihydrobiliverdin IX alpha is a partially reduced intermediate in the formation of phycobilins from biliverdin IX alpha
Journal: J Biol Chem
Volume: 266
Issue: 33
Pages: 22341-22345
Date: Nov 25
Abstract: A partially purified protein fraction from the phycocyanin-containing unicellular rhodophyte, Cyanidium caldarium, reductively transforms biliverdin IX alpha to a violet colored bilin in the presence of NADPH, ferredoxin, and ferredoxin-NADP+ reductase. This bilin has a violin-like absorption spectrum with maxima at 335 and 560 nm in methanolic HCl and at 337, 567, and 603-604 nm in CHCl3. The bilin has been determined to be 15,16-dihydrobiliverdin IX alpha by comparative spectrophotometry and 1H NMR spectroscopy. This product of biliverdin IX alpha reduction is converted enzymatically to phycobilins by further reduction. A general biosynthetic pathway is proposed which accounts for the formation of the phycobilins from biliverdin IX alpha by a two-step reduction process followed by isomerization.

Author: Valentin, K.; Zetsche, K.
Year: 1990
Title: Structure of the Rubisco operon from the unicellular red alga Cyanidium caldarium: evidence for a polyphyletic origin of the plastids
Journal: Mol Gen Genet
Volume: 222
Issue: 2-3
Pages: 425-430
Date: Jul
Abstract: The genes for both subunits of ribulose-1,5-bisphosphate-carboxylase/oxygenase (Rubisco) were located on the plastid DNA (ptDNA) of the unicellular red alga Cyanidium caldarium. Both genes are organized together in an operon. The sequence homology of both genes to the corresponding genes from the unicellular red alga Porphyridium aerugineum is remarkably high, whereas homology to Rubisco genes from chloroplasts and two recent cyanobacteria is significantly lower. These data provide strong evidence for a polyphyletic origin of chloroplasts and rhodoplasts. In addition the genes for the small subunit of Rubisco (rbcS) from red algae show about 60% homology to rbcS genes from cryptophytes and chromophytes. Thus, homologies in the rbcS gene indicate a close phylogenetic relationship between rhodoplasts and the plastids of Chromophyta.

Author: Maid, U.; Valentin, K.; Zetsche, K.
Year: 1990
Title: The psbA-gene from a red alga resembles those from cyanobacteria and cyanelles
Journal: Curr Genet
Volume: 17
Issue: 3
Pages: 255-259
Date: Mar
Abstract: Plastid DNA (ptDNA) from the unicellular red alga Cyanidium caldarium was isolated. A 5.8 kb Eco RI, fragment containing the entire psbA-gene was cloned and the nucleotide sequence of the psbA-gene determined. At the carboxyl terminus the encoded protein (D1) contains the seven amino acid-insertion which was found to be typical of the cyanobacteria and the cyanelles of Cyanophora paradoxa. However, the overall sequence homology does not support a direct relationship between the plastids of Cyanidium, cyanelles and the cyanobacteria. As in other photosynthetic organisms the psbA-gene is transcribed as a monocistronic mRNA. The ribosomal RNA operon was located 4 kb upstream of the psbA-gene.

Author: Maid, U.; Zetsche, K.
Year: 1990
Title: Nucleotide sequence of the plastid 16S rRNA gene of the red alga Cyanidium caldarium
Journal: Nucleic Acids Res
Volume: 18
Issue: 13
Pages: 3996
Date: Jul 11

Author: Kostrzewa, M.; Valentin, K.; Maid, U.; Radetzky, R.; Zetsche, K.
Year: 1990
Title: Structure of the rubisco operon from the multicellular red alga Antithamnion spec
Journal: Curr Genet
Volume: 18
Issue: 5
Pages: 465-469
Date: Dec
Abstract: In the multicellular red alga Antithamnion spec. both rubisco genes (rbcL and rbcS) are encoded on the plastid DNA (ptDNA). Both genes are separated by a short A/T-rich spacer of 100 bp and are cotranscribed into an mRNA of approximately 2.7 kb. These findings are in extensive agreement with those obtained from two unicellular red algae (Porphyridium aerugineum and Cyanidium caldarium). The large subunit (LSU) of rubisco shows an amino acid homology of 82-87% with the LSUs from the two unicellular red algae and only about 55% to LSUs from green algae, higher plants and two cyanobacteria. The small subunit (SSU) of rubisco is more similar to those from the unicellular red algae and two algae which are members of the Chromophyta (about 60% homology) than to cyanobacterial and higher plant proteins (27-36% homology). These data indicate that rhodoplasts originated independently from the chloroplast line. The plastids of chromophytes and rhodophytes appear to be closely related.

Author: Troxler, R. F.; Lin, S.; Offner, G. D.
Year: 1989
Title: Heme regulates expression of phycobiliprotein photogenes in the unicellular rhodophyte, Cyanidium caldarium
Journal: J Biol Chem
Volume: 264
Issue: 34
Pages: 20596-20601
Date: Dec 5
Abstract: Allophycocyanin and phycocyanin in the red alga (Cyanidium caldarium) are chloroplast-encoded, light-harvesting accessory pigments composed of alpha and beta subunit polypeptides (17-19 kDa) to which 1 or more residues of the heme-derived bile pigment chromophore phycocyanobilin are attached by cysteinyl thioether linkages (Offner, G.D., and Troxler, R.F. (1983) J. Biol. Chem. 258, 9931-9940). Western blot experiments utilizing phycobiliprotein antisera revealed that immunoreactive allophycocyanin and phycocyanin apoproteins were absent in cells grown in the dark and present in cells exposed to light. Northern blot experiments using genomic DNA hybridization probes indicated that phycobiliprotein mRNAs were absent in the dark, whereas cells exposed to light contained two allophycocyanin mRNA transcripts, 1.4 and 1.6 kilobases in length, and one phycocyanin mRNA transcript, 3.0 kilobases in length, providing evidence that phycobiliproteins are encoded in photogenes which are only transcriptionally active in the light. Northern and Western analyses demonstrated that cells incubated in the dark with the heme precursor delta-aminolevulinate contained allophycocyanin and phycocyanin mRNAs and apoproteins, indistinguishable in size, number, and quantity from those made in the light. Cells incubated in the dark with delta-aminolevulinate, protoporphyrin IX, or heme, but not biliverdin or phycocyanobilin, synthesized allophycocyanin and phycocyanin alpha and beta apoproteins, suggesting a role for heme in the control phycobiliprotein gene expression. Cells incubated with heme in the dark produced allophycocyanin and phycocyanin mRNA transcripts, but did not produce mRNAs for four other photogenes coding for a P-700 reaction center protein, a 32-kDa herbicide-binding protein, and the large and small subunits of ribulose-bisphosphate carboxylase. These results show, for the first time, that heme is a regulatory factor specifically involved in transcriptional regulation of chloroplast genes for phycobiliproteins.

Author: Nagashima, H.; Sakai, K.; Kamo, M.; Tsugita, A.
Year: 1989
Title: Amino acid sequence of ferredoxin isolated from Cyanidium caldarium strain RK-1
Journal: Protein Seq Data Anal
Volume: 2
Issue: 6
Pages: 457-460
Date: Dec
Abstract: Ferredoxin was isolated from ther eukaryotic alga Cyanidium caldarium strain RK-1 and its amino acid sequence was determined. The ferredoxin is composed of 97 amino acid residues, and its molecular weight is 10,599 excluding the iron-sulfur cluster. The amino acid sequence differs from that of C. caldarium strain 1355/1, by 24 amino acid substitutions plus one deletion at the amino terminus.

Author: Brown, S. B.; Holroyd, J. A.; Vernon, D. I.; Shim, Y. K.; Smith, K. M.
Year: 1989
Title: The biosynthesis of the chromophore of phycocyanin. Pathway of reduction of biliverdin to phycocyanobilin
Journal: Biochem J
Volume: 261
Issue: 1
Pages: 259-263
Date: Jul 1
Abstract: The later stages in the pathway of biosynthesis of phycocyanobilin, the chromophore of phycocyanin, were studied by using radiolabelled intermediates. Three possible pathways from biliverdin IX-alpha to phycocyanobilin were considered. 14C-labelled samples of key intermediates in two of the pathways, 3-vinyl-18-ethyl biliverdin IX-alpha and 3-ethyl-18-vinyl biliverdin IX-alpha, were synthesized chemically and were administered to cultures of Cyanidium caldarium that were actively synthesizing photosynthetic pigments in the light. Neither of these two compounds was apparently incorporated into the phycobiliprotein chromophore, suggesting that two of the three pathways were not operative. By elimination, the results imply that the third possible pathway, which involves phytochromobilin, the chromophore of phytochrome, represents the route for biosynthesis of phycocyanobilin. Unfortunately, since 14C-labelled phytochromobilin is not available, no direct proof of this pathway could be obtained. However, if correct, the present interpretation represents a unified pathway for biosynthesis of all plant bilins, via the intermediacy of phytochromobilin.

Author: Houghton, J. D.; Turner, L.; Brown, S. B.
Year: 1988
Title: The effect of gabaculine on tetrapyrrole biosynthesis and heterotrophic growth in Cyanidium caldarium
Journal: Biochem J
Volume: 254
Issue: 3
Pages: 907-910
Date: Sep 15
Abstract: Pigment synthesis in four strains of the unicellular red alga Cyanidium caldarium with different pigment-synthesizing patterns was inhibited in the presence of gabaculine (3-amino-2,3-dihydrobenzoic acid). Parallel inhibition of light-induced chlorophyll and phycocyanin synthesis was observed in strain III-D-2, which only synthesizes pigments in the light. Similar parallel inhibition was observed in the dark in mutant CPD, which is able to synthesize chlorophyll and phycocyanin in the absence of light. Inhibition of pigment synthesis in all strains was overcome by addition of 5-aminolaevulinic acid. Inhibition of phycocyanin synthesis in mutant GGB (unable to synthesize chlorophyll) and inhibition of chlorophyll synthesis in mutant III-C (unable to synthesize phycocyanin) were also observed. Gabaculine also inhibited the heterotrophic growth of C. caldarium in the dark. However, inhibition was overcome after an extended lag period, following which cell growth proceeded at a similar rate to that of control cells not exposed to gabaculine. Heterotrophic growth in cells pre-exposed to gabaculine was not inhibited by subsequent exposure. Possible mechanisms for this adaptation are discussed.

Author: Cornejo, J.; Beale, S. I.
Year: 1988
Title: Algal heme oxygenase from Cyanidium caldarium. Partial purification and fractionation into three required protein components
Journal: J Biol Chem
Volume: 263
Issue: 24
Pages: 11915-11921
Date: Aug 25
Abstract: Enzymatic heme oxygenase activity has been partially purified from extracts of the unicellular red alga Cyanidium caldarium, and the macromolecular components have been separated into three protein fractions, referred to as Fractions I, II, and III, by serial column chromatography through DEAE-cellulose and Reactive Blue 2-Sepharose. Fraction I is retained by DEAE-cellulose at low salt concentration and eluted by 1 M NaCl. Fraction II is retained by Blue Sepharose at low salt concentration and eluted by 1 M NaCl. Fraction III is retained on 2',5'-ADP-agarose and eluted by 1 mM NADPH, while Fraction II is not retained on ADP-agarose. Fractions I-III, have Mr values of 22,000, 38,000, and 37,000, respectively (all +/- 2,000), as determined by Sephadex gel filtration chromatography. In vitro heme oxygenase activity requires the presence of all three fractions, plus substrate, O2, reduced pyridine nucleotide, and another reductant. Ascorbate, isoascorbate, and phenylenediamine serve equally well as the second reductant, but hydroquinone can also be used, with lower activity resulting. Fractions I-III are heat sensitive and inactive by Pronase digestion. Fraction I has a visible absorption spectrum similar to that of ferredoxin and is bleached by dithionite reduction or incubation with p-hydroxymercuribenzoate. Fraction I can be replaced by commercially available ferredoxin derived from the red alga Porphyra umbilicalis, and to a smaller extent, by spinach ferredoxin. Fraction III contains ferredoxin-linked cytochrome c reductase activity and can be partially replaced by spinach ferredoxin-NADP+ oxidoreductase. Reconstituted heme oxygenase and ferredoxin-linked cytochrome c reductase activities are both abolished if Fraction I or III is preincubated with 0.1 mM p-hydroxymercuribenzoate, but heme oxygenase activity is only slightly affected if Fraction II is preincubated with p-hydroxymercuribenzoate. Preincubation of Fraction II with 0.5 mM diethylpyrocarbonate inactivates heme oxygenase in the reconstituted system, and 10 microM mesohemin partially protects this Fraction against diethylpyrocarbonate inactivation. Algal heme oxygenase is inhibited 80% by 2 microM Sn-protoporphyrin even in the presence of 20 microM mesohemin. Fraction II is rate limiting in unfractionated and reconstituted incubation mixtures. None of the three cell fractions could be replaced by bovine spleen microsomal heme oxygenase or NADPH-cytochrome P450 reductase.

Author: Mayer, S. M.; Beale, S. I.; Weinstein, J. D.
Year: 1987
Title: Enzymatic conversion of glutamate to delta-aminolevulinic acid in soluble extracts of Euglena gracilis
Journal: J Biol Chem
Volume: 262
Issue: 26
Pages: 12541-12549
Date: Sep 15
Abstract: Glutamate was converted to the chlorophyll and heme precursor delta-aminolevulinic acid in soluble extracts of Euglena gracilis. delta-Aminolevulinic acid-forming activity depended on the presence of native enzyme, glutamate, ATP, Mg2+, NADPH or NADH, and RNA. The requirement for reduced pyridine nucleotide was observed only if, prior to incubation, the enzyme extract was filtered through activated carbon to remove firmly bound reductant. Dithiothreitol was also required for activity after carbon treatment. delta-Aminolevulinic acid formation was stimulated by RNA from various plant tissues and algal cells, including greening barley leaves and members of the algal groups Chlorophyta (Chlorella vulgaris, Chlamydomonas reinhardtii), Rhodophyta (Cyanidium caldarium), Cyanophyta (Anacystis nidulans, Synechocystis sp. PCC 6803), and Prochlorophyta (Prochlorothrix hollandica), but not by RNA derived from Escherichia coli, yeast, wheat germ, bovine liver, and Methanobacterium thermoautotrophicum. E. coli glutamate-specific tRNA was inhibitory. Several of the RNAs that did not stimulate delta-aminolevulinic acid formation nevertheless became acylated when incubated with glutamate in the presence of Euglena enzyme extract. RNA extracted from nongreen dark-grown wild-type Euglena cells was about half as stimulatory as that from chlorophyllous light-grown cells, and RNA from aplastidic mutant cells stimulated only slightly. delta-Aminolevulinic acid-forming enzyme activity was present in extracts of light-grown wild-type cells, but undetectable in extracts of aplastidic mutant and dark-grown wild-type cells. Gabaculine inhibited delta-aminolevulinic acid formation at submicromolar concentration. Heme inhibited 50% at 25 microM, but protoporphyrin IX, Mg-protoporphyrin IX, and protochlorophyllide inhibited only slightly at this concentration.

Author: Hamana, K.; Matsuzaki, S.
Year: 1985
Title: Further study on polyamines in primitive unicellular eukaryotic algae
Journal: J Biochem (Tokyo)
Volume: 97
Issue: 5
Pages: 1311-1315
Date: May
Abstract: The possible usefulness of polyamines as chemotaxonomic markers has been investigated in eukaryotic algae. Polyamines were analyzed in 12 species of primitive unicellular eukaryotic algae including some anomalous species. Norspermidine and norspermine in addition to putrescine and spermidine are widely distributed in most unicellular species of the algae. However, neither norspermidine nor norspermine was found in the taxonomically conflicting algae, Cyanophora and Glaucocystis, which contain cyanellae, or in a primitive red alga, Porphyridium. A thermoacidophilic eukaryotic alga, Cyanidium, is rich in both norspermidine and norspermine. Appreciable amounts of spermine and sym-homospermidine were detected only in the species belonging to the Rhodophyta (red algae).

Author: Seckbach, J.; Ott, F.D.
Year: 1984
Title: Systematic position and phylogentic status of Cyanidium caldarium Geitler 1933.
Editor: Seckbach, J.
Book Title: Evolutionary pathway and enigmatic algae: Cyanidium caldarium (Rhodophyta) and related cells
City: Dordrecht, NL
Publisher: Kluwer Academic Publishers
Pages: 133-143

Author: Di Martino Rigano, V.; Vona, V.; Fuggi, A.; Martello, A.; Di Martino, C.; Rigano, C.
Year: 1984
Title: Depression of nitrate reductase in the presence of excess ammonium in a unicellular alga growing under conditions of phosphate limitation
Journal: Biochem Biophys Res Commun
Volume: 119
Issue: 1
Pages: 259-264
Date: Feb 29
Abstract: Chemostat cultures of the unicellular alga Cyanidium caldarium have shown that under conditions of phosphate limitation nitrate reductase is completely derepressed even in cells growing in a large excess of ammonium, but that it occurs mainly in a catalytically inactive form. It is hypothesized that phosphate limitation contributes to maintaining intracellular level of glutamine suitable to stimulate inactivation but not repression of nitrate reductase. It is not excluded that in addition to variations in the intracellular level of glutamine, there are other metabolic events of the cell by which repression and inactivation of nitrate reductase could be differently influenced.

Author: Brown, S. B.; Holroyd, J. A.
Year: 1984
Title: Biosynthesis of the chromophore of phycobiliproteins. A study of mesohaem and mesobiliverdin as possible intermediates and further evidence for an algal haem oxygenase
Journal: Biochem J
Volume: 217
Issue: 1
Pages: 265-272
Date: Jan 1
Abstract: The possible roles of mesohaem and mesobiliverdin as metabolic precursors of phycocyanobilin, the chromophore of phycocyanin, were studied in the unicellular rhodophyte Cyanidium caldarium. Dark-grown cells of this organism, which had been exposed to mesohaem, were either incubated in the dark with 5-aminolaevulinate, which results in excretion of bilins into the suspending medium, or incubated in the light, which results in synthesis of phycocyanin within the cells. By using 14C-labelling, either in the mesohaem or in the 5-aminolaevulinate administered, it was shown that mesohaem is not a precursor of phycocyanobilin in either dark or light systems. However, mesohaem was converted into mesobiliverdin in both systems, a phenomenon that is further evidence for the existence of an algal haem oxygenase. The data also showed that mesobiliverdin is not a precursor of phycocyanobilin. These results suggest that algal bilins are formed via haem degradation to biliverdin in the same way as mammalian bile pigments.

Author: Brown, S. B.; Holroyd, J. A.; Vernon, D. I.
Year: 1984
Title: Biosynthesis of phycobiliproteins. Incorporation of biliverdin into phycocyanin of the red alga Cyanidium caldarium
Journal: Biochem J
Volume: 219
Issue: 3
Pages: 905-909
Date: May 1
Abstract: 14C-labelled biliverdin IX alpha was administered to cultures of Cyanidium caldarium that were actively synthesizing photosynthetic pigments in the light. Between 9 and 12% of the phycobiliprotein chromophore produced in such cultures was derived from exogenous biliverdin. These results demonstrate that biliverdin is an intermediate in the biosynthesis of phycobiliproteins.

Author: Brown, S. B.; Holroyd, J. A.; Vernon, D. I.; Jones, O. T.
Year: 1984
Title: Ferrochelatase activity in the photosynthetic alga Cyanidium caldarium. Development of the enzyme during biosynthesis of photosynthetic pigments
Journal: Biochem J
Volume: 220
Issue: 3
Pages: 861-863
Date: Jun 15
Abstract: Dark-grown cells of the photosynthetic alga Cyanidium caldarium were shown to contain ferrochelatase activity, which increased markedly when the cells were induced to form pigments by exposure to light. Km values for the crude enzyme preparation were 14.8 microM and 6.5 microM for binding of Co2+ and deuteroporphyrin IX respectively.

Author: Beale, S. I.; Cornejo, J.
Year: 1984
Title: Enzymatic heme oxygenase activity in soluble extracts of the unicellular red alga, Cyanidium caldarium
Journal: Arch Biochem Biophys
Volume: 235
Issue: 2
Pages: 371-384
Date: Dec
Abstract: Extracts of the phycocyanin-containing unicellular red alga, Cyanidium caldarium, catalyzed enzymatic cleavage of the heme macrocycle to form the linear tetrapyrrole bilin structure. This is the key first step in the branch of the tetrapyrrole biosynthetic pathway leading to phycobilin photosynthetic accessory pigments. A mixed-function oxidase mechanism, similar to the biliverdin-forming reaction catalyzed by animal cell-derived microsomal heme oxygenase, was indicated by requirements for O2 and a reduced pyridine nucleotide. To avoid enzymatic conversion of the bilin product to phycocyanobilins and subsequent degradation during incubation, mesoheme IX was substituted for the normal physiological substrate, protoheme IX. Mesobiliverdin IX alpha was identified as the primary incubation product by comparative reverse-phase high-pressure liquid chromatography and absorption spectrophotometry. The enzymatic nature of the reaction was indicated by the requirement for cell extract, absence of activity in boiled cell extract, high specificity for NADPH as cosubstrate, formation of the physiologically relevant IX alpha bilin isomer, and over 75% inhibition by 1 microM Sn-protoporphyrin, which has been reported to be a competitive inhibitor of animal microsomal heme oxygenase. On the other hand, coupled oxidation of mesoheme, catalyzed by ascorbate plus pyridine or myoglobin, yielded a mixture of ring-opening mesobiliverdin IX isomers, was not inhibited by Sn-protoporphyrin, and could not use NADPH as the reductant. Unlike the animal microsomal heme oxygenase, the algal reaction appeared to be catalyzed by a soluble enzyme that was not sedimentable by centrifugation for 1 h at 200,000g. Although NADPH was the preferred reductant, small amounts of activity were obtained with NADH or ascorbate. A portion of the activity was retained after gel filtration of the cell extract to remove low-molecular-weight components. Considerable stimulation of activity, particularly in preparations that had been subjected to gel filtration, was obtained by addition of ascorbate to the incubation mixture containing NADPH. The results indicate that C. caldarium possesses a true heme oxygenase system, with properties somewhat different from that catalyzing heme degradation in animals. Taken together with previous results indicating that biliverdin is a precursor to phycocyanobilin, the results suggest that algal heme oxygenase is a component of the phycobilin biosynthetic pathway.

Author: Offner, G. D.; Troxler, R. F.
Year: 1983
Title: Primary structure of allophycocyanin from the unicellular rhodophyte, Cyanidium caldarium. The complete amino acid sequences of the alpha and beta subunits
Journal: J Biol Chem
Volume: 258
Issue: 16
Pages: 9931-9940
Date: Aug 25
Abstract: The complete amino acid sequences of the alpha and beta subunits of allophycocyanin from the unicellular rhodophyte, Cyanidium caldarium, were determined by automated Edman degradation of the proteins and peptides derived from them by chemical and enzymatic cleavages. The sequence of the alpha subunit was determined from the sequences of tryptic, endoproteinase lysine-C, and cyanogen bromide peptides and carboxypeptidase A and Y digestion of the protein. The sequence of the beta subunit was determined from the sequences of tryptic, endoproteinase lysine-C, Staphylococcus aureus V8 protease, and cyanogen bromide peptides and in addition, a peptide derived from acid cleavage of an aspartyl-prolyl bond. The carboxyl-terminal sequence of the protein was determined by digestion with carboxypeptidase A. The alpha subunit contains 160 amino acids, one phycocyanobilin chromophore attached at residue 80 by a cysteinyl-thioether linkage, and the Mr calculated from the sequence is 18,160. The beta subunit contains 161 amino acids, one phycocyanobilin chromophore attached at residue 81 by a cysteinyl-thioether linkage, and the Mr calculated from the sequence is 18,125. The amino acid sequences of the alpha and beta subunits of allophycocyanin from C. caldarium are the first complete amino acid sequences of an allophycocyanin from a eukaryotic red alga. A matrix comparison of the alpha and beta subunits of C. caldarium allophycocyanin and phycocyanin (Offner, G.D., Brown-Mason, A.S., Ehrhardt, M. M., and Troxler, R. F. (1981) J. Biol. Chem. 256, 12167-12175; Troxler, R. F., Ehrhardt, M. M., Brown-Mason, A. S., and Offner, G. D. (1981) J. Biol. Chem. 256, 12176-12184) shows homology ranging from 26 to 39%. Comparison of the sequences of alpha and beta subunits of C. caldarium allophycocyanin with the sequences of the corresponding subunits of allophycocyanin from two prokaryotic cyanobacteria (Sidler, W., Gysi, J., Isker, E., and Zuber, H. (1981) Hoppe-Seyler's Z. Physiol. Chem. 362, 611-628; DeLange, R. J., Williams, L. C. and Glazer, A. N. (1981) J. Biol. Chem. 256, 9558-9566) shows homology ranging from 81 to 85%. The significance of this with respect to phycobiliprotein structure and function is discussed.

Author: De Luca, P.; Moretti, A.
Year: 1983
Title: Floridosides in Cyanidium caldarium, Cyanidioschyzon merolae and Galdieria sulphuraria (Rhodophyta, Cyanidiophyceae)
Journal: J. Phycol.
Volume: 19
Issue: 3
Pages: 368-369
Go to ISI:A1983RM20900017

Author: Belford, H. S.; Offner, G. D.; Troxler, R. F.
Year: 1983
Title: Phycobiliprotein synthesis in the unicellular rhodophyte, Cyanidium caldarium. Cell-free translation of the mRNAs for the alpha and beta subunit polypeptides of phycocyanin
Journal: J Biol Chem
Volume: 258
Issue: 7
Pages: 4503-4510
Date: Apr 10
Abstract: Phycobiliproteins are a class of abundant light-harvesting proteins assembled in complex multimeric aggregates located on thylakoid membranes of red algae and cyanobacteria. This study was undertaken to investigate the molecular basis of phycobiliprotein synthesis in the unicellular red alga, Cyanidium caldarium. RNA was isolated and separated into poly(A)-enriched and poly(A)-deficient fractions by oligo(dT)-cellulose chromatography. Both fractions stimulated incorporation of radiolabeled amino acids into protein in a reticulocyte lysate translation system. The alpha and beta subunit polypeptides of phycocyanin were among the products of poly(A)-deficient (but not poly(A)-enriched) RNA directed translation reactions on the basis of Mr and immunological cross-reactivity with immune serum prepared against native phycocyanin. After chromatography of post-oligo(dT)-cellulose poly(A)-deficient RNA on poly(U) agarose, the messenger RNAs for the alpha and beta subunit polypeptides of phycocyanin were again recovered in the poly(A)-deficient fraction, confirming that these messenger RNAs did not appear to be polyadenylated. Automated radiosequencing of in vitro synthesized alpha and beta subunit polypeptides of phycocyanin labeled with either [35S]methionine, [3H]isoleucine, or [3H]phenylalanine revealed partial amino acid sequences which were the same as the NH2-terminal sequences of native phycocyanin subunits. This demonstrates that a "transit peptide", such as that found in several proteins made in the cytosol and transported into chloroplasts, is not present on the subunits of phycocyanin.

Author: Beale, S. I.; Cornejo, J.
Year: 1983
Title: Biosynthesis of phycocyanobilin from exogenous labeled biliverdin in Cyanidium caldarium
Journal: Arch Biochem Biophys
Volume: 227
Issue: 1
Pages: 279-286
Date: Nov
Abstract: Phycocyanin is a major light-harvesting pigment in bluegreen, red, and cryptomonad algae. This pigment is composed of phycocyanobilin chromophores covalently attached to protein. Phycocyanobilin is an open-chain tetrapyrrole structurally close to biliverdin. Biliverdin is formed in animals by oxidative ring-opening of protoheme. Recent evidence indicates that protoheme is a precursor of phycocyanobilin in the unicellular rhodophyte, Cyanidium caldarium. To find out if biliverdin is an intermediate in the conversion of protoheme to phycocyanobilin, [14C]biliverdin was administered along with N-methylmesoporphyrin IX (which blocks endogenous protoheme formation) to growing cells of C. caldarium. To avoid phototoxic effects due to the porphyrin, a mutant strain was used that forms large amounts of both chlorophyll and phycocyanin in the dark. After 12 or 24 h in the dark, cells were harvested and exhaustively extracted to remove free pigments. Next, protoheme was extracted. Phycocyanobilin was then cleaved from the apoprotein by methanolysis. Protoheme and phycocyanobilin were purified by solvent partition, DEAE-Sepharose chromatography, and preparative reverse-phase high-pressure liquid chromatography. Absorption was monitored continuously and fractions were collected for radioactivity determination. Negligible amounts of label appeared in the protoheme-containing fractions. A major portion of label in the eluates of the phycocyanobilin-containing samples coincided with the absorption peak at 22 min due to phycocyanobilin. In a control experiment, [14C]biliverdin was added to the cells after incubation and just before the phycocyanobilin-apoprotein cleavage step. The major peak of label then eluted with the absorption peak at 12 min due to biliverdin, indicating that during the isolation biliverdin is not converted to compounds coeluting with phycocyanobilin. It thus appears that exogenous biliverdin can serve as a precursor to phycocyanobilin in C. caldarium, and that the route of incorporation is direct rather than by degradation and reincorporation of 14C through protoheme.

Author: Brown, S. B.; Holroyd, J. A.; Vernon, D. I.; Troxler, R. F.; Smith, K. M.
Year: 1982
Title: The effect of N-methylprotoporphyrin IX on the synthesis of photosynthetic pigments in Cyanidium caldarium. Further evidence for the role of haem in the biosynthesis of plant billins
Journal: Biochem J
Volume: 208
Issue: 2
Pages: 487-491
Date: Nov 15

Author: Troxler, R. F.; Ehrhardt, M. M.; Brown-Mason, A. S.; Offner, G. D.
Year: 1981
Title: Primary structure of phycocyanin from the unicellular rhodophyte Cyanidium caldarium. II. Complete amino acid sequence of the beta subunit
Journal: J Biol Chem
Volume: 256
Issue: 23
Pages: 12176-12184
Date: Dec 10
Abstract: The complete amino acid sequence of the beta subunit of phycocyanin from the unicellular rhodophyte Cyanidium caldarium, has been determined by automated sequential degradation of cyanogen bromide, tryptic, and Staphylococcus aureus V8 protease peptides. The beta subunit contains 172 amino acids with methionine and glutamine the NH2- and carboxyl-terminal amino acids, respectively. The calculated molecular weight of the protein, based on the sequence, is 19,572. Two phycocyanobilin chromophores are covalently attached by cysteinyl thioether linkages to residues 82 and 153. A third cystine (residue 109) occurs in the beta subunit, but it is not attached to phycocyanobilin. Comparison of the complete amino acid sequence of the beta subunit of C. caldarium phycocyanin with the sequences of the phycocyanin beta subunits from two cyanobacteria, shows that the sequence homology previously noted at the NH2 terminus of phycobiliproteins from distantly related organisms extends along the entire polypeptide chain. The amino acid sequences of the alpha and beta subunits of C. caldarium phycocyanin are also similar, and by proper alignment of the sequences it can be shown that the beta subunit contains a 12-residue insertion where the second phycocyanobilin chromophore is covalently attached. A matrix comparing the alpha and beta subunits of phycobiliproteins for which the complete sequences are known has been determined, and based on these data, a scheme is proposed for evolution of the family of phycobiliproteins in living cyanobacteria and red algae from a protein precursor which gave rise initially to a beta-type allophycocyanin subunit.

Author: Seckbach, J.; Hammerman, I. S.; Hanania, J.
Year: 1981
Title: Ultrastructural studies of cyanidium caldarium: contribution to phylogenesis
Journal: Ann N Y Acad Sci
Volume: 361
Pages: 409-425

Author: Offner, G. D.; Brown-Mason, A. S.; Ehrhardt, M. M.; Troxler, R. F.
Year: 1981
Title: Primary structure of phycocyanin from the unicellular rhodophyte Cyanidium caldarium. I. Complete amino acid sequence of the alpha subunit
Journal: J Biol Chem
Volume: 256
Issue: 23
Pages: 12167-12175
Date: Dec 10
Abstract: The complete amino acid sequence of the alpha subunit of phycocyanin from the unicellular rhodophyte Cyanidium caldarium has been determined by automated sequential degradation of cyanogen bromide peptides, tryptic peptides derived from protein chemically modified with 1,2-cyclohexanedione or citraconic anhydride, and a peptide obtained after cleavage of the protein at the single tryptophan residue. The alpha subunit contains 162 amino acids and methionine and serine are the NH2- and carboxyl-terminal amino acids, respectively. The calculated molecular weight of the protein, based on the amino acid sequence, is 18,303, in good agreement with the value of 17,500 +/- 500, obtained by electrophoresis on calibrated sodium dodecyl sulfate-polyacrylamide gels. One phycocyanobilin chromophore is attached to the alpha subunit at residue 84 by a cysteinyl thioether linkage. A second cysteine (residue 98) is present but is not linked to phycocyanobilin. The amino acid sequence of the alpha subunit of phycocyanin from C. caldarium is the first complete amino acid sequence of a phycobiliprotein from a eukaryotic alga. Extensive homology occurs between the alpha subunit of phycocyanin from C. caldarium and from two prokaryotic cyanobacteria, and the significance of this is discussed.

Author: Merola, A.; Castaldo, R.; De Luca, P.; Gambardella, R.; Musachio, A.; Taddei, R.
Year: 1981
Title: Revision of Cyanidium caldarium. Three species of acidophylic algae.
Journal: Giorn Bot Ital
Volume: 115
Pages: 189-195

Author: Brown, S. B.; Holroyd, J. A.; Troxler, R. F.; Offner, G. D.
Year: 1981
Title: Bile pigment synthesis in plants. Incorporation of haem into phycocyanobilin and phycobiliproteins in Cyanidium caldarium
Journal: Biochem J
Volume: 194
Issue: 1
Pages: 137-147
Date: Jan 15
Abstract: A procedure was developed whereby haem was taken up by dark-grown cells of the unicellular rhodophyte Cyanidium caldarium. These cells were subsequently incubated either in the dark with 5-aminolaevulinate, which results in excretion of phycocyanobilin into the suspending medium or incubated in the light, which results in synthesis and accumulation of phycocyanin and chlorophyll a within the cells. Phycocyanobilin was isolated from phycocyanin by cleavage from apoprotein in methanol. Phycocyanobilin prepared from phycocyanin or excreted from cells given 5-aminolaevulinate was methylated and purified by t.l.c. By using 14C labelling either in the haem or in 5-aminolaevulinate administered, haem incorporation into phycocyanobilin was demonstrated in both dark and light systems. Since chlorophyll a synthesized in the light in the presence of labelled haem contained no radioactivity, it was clear that haem was directly incorporated into phycocyanobilin and not first converted into protoporphyrin IX. These results clearly demonstrate phycocyanobilin synthesis via haem and not via magnesium protoporphyrin IX as has also been postulated.

Author: Baianova Iu, I.; Trubachev, I. N.
Year: 1981
Title: Comparative evaluation of the vitamin composition of unicellular algae and higher plants grown under artificial conditions
Journal: Prikl Biokhim Mikrobiol
Volume: 17
Issue: 3
Pages: 400-407
Date: May-Jun
Abstract: The vitamin composition of representatives of green (Chlorella vulgaris, Platimonas viridis), blue-green (Synechococcus elongatus, Coccopedia, Spirulina platensis, Cyanidium caldarium), red (Porphyridium cruentum) unicellular algae and higher plants (wheat, chufa, beet, carrot, turnip, radish, cucumber, dill, Welsh onion, potato) grown under artificial conditions was examined. The content of B complex vitamins (thiamine, riboflavine, nicotinic and folic acids), ascorbic acid and carotene was measured. Among the algae studied Chlorella vulgaris and Spirulina platensis showed the highest vitamin activity. The red alga Porphyridium cruentum contained the lowest quantity of thiamine, riboflavine and carotene and larger amounts of nicotinic acid. Comparison of the content of vitamins C, B1, B2, PP, folic acid and carotene in unicellular algae and higher plants, that are natural and traditional sources of the vitamins, demonstrated that the above green and blue-green algae contain greater than higher plants amounts of thiamine, riboflavine, folic acid and carotene, when calculated per g dry matter. All algae, except for Platimonas viridis and Cyanidium caldarium, are superior to beet and carrot in their content of ascorbic acid and inferior to green vegetables (radish, cabbage, dill and Welsh onion) in that parameter.

Author: Sonneveld, A.; Rademaker, H.; Duysens, L. N.
Year: 1980
Title: Transfer and trapping of excitation energy in photosystem II as studied by chlorophyll alpha 2 fluorescence quenching by dinitrobenzene and carotenoid triplet. The matrix model
Journal: Biochim Biophys Acta
Volume: 593
Issue: 2
Pages: 272-289
Date: Dec 3
Abstract: 1. The curves representing the reciprocal fluorescence yield of chlorophyll alpha of Photosystem II (PS II) in Chlorella vulgaris as a function of the concentration of m-dinitrobenzene in the states P Q and P Q-, are found to be straight parallel lines; P is the primary donor and Q the primary acceptor of PS II. In the weakly trapping state P Q- the half-quenching of dinitrobenzene is about 0.2 mM, in vitro it is of the order of 10 mM. The fluorescence yield as a function of the concentration of a quencher is described for three models for the energy transfer between the units, and the matrix model. If it is assumed that the rate constant of quenching by dinitrobenzene is high and thus the number of dinitrobenzene molecules per reaction center low, it can be concluded that the pigment system of PS II in C. vulgaris is a matrix of chlorophyll molecules in which the reaction centers are embedded. Theoretical and experimental evidence is consistent with such an assumption. For Cyanidium caldarium the zero fluorescence yield phi 0 and its quenching by dinitrobenzene were found to be much smaller than the corresponding quantities for C. vulgaris. Nevertheless, our measurements on C. caldarium could be interpreted by the assumption that the essential properties (rate constants, dinitrobenzene quenching) of PS II are the same for these two species belonging to such widely different groups. 2. The measured dinitrobenzene concentrations required for half-quenching in vivo and other observations are explained by (non-rate-limiting) energy transfer between the chlorophyll alpha molecules of PS II and by the assumptions that dinitrobenzene is approximately distributed at random in the membrane and does not diffuse during excitation. 3. The fluorescence kinetics of C. vulgaris during a 350 ns laser flash of variable intensity could be simulated on a computer using the matrix model. From the observed fluorescence quenching by the carotenoid triplet (CT) and the measurement of the the number of CT per reaction center via difference absorption spectroscopy, the rate constant for quenching of CT is calculated to be kT = 3.3 . 10(11)s-1 which is almost equal to the rate constant of trapping by an open reaction center (Duysens, L.N.M. (1979) CIBA Foundation Symposium 61 (New Series), pp. 323--340). 4. The fluorescence quenching by CT in non-treated spinach chloroplasts after a 500 ns laser flash (Breton, J., Geacintov, N.E. and Swenberg, C.E. (1979) Biochim, Biophys. Acta 548, 616--635) could be explained within the framework of the matrix model when the value for kT is used as given in point 3. 5. The observations mentioned under point 1 indicate that the fluorescence yield phi 0 for centers in trapping state P Q is probably for a fraction exceeding 0.8 emitted by PS II.

Author: Seckbach, J.; Fredrick, J. F.
Year: 1980
Title: A primaeval alga bridging the blue-green and the red algae: further biochemical and ultrastructure studies of Cyanidium caldarium with special reference to the plastid membranes
Journal: Microbios
Volume: 29
Issue: 117-118
Pages: 135-147
Abstract: The storage polyglucan and isozyme distribution together with the fine structure of the chloroplasts have been investigated in Cyanidium caldarium. This alga is a unicellular eukaryote which thrives in acid hot habitats. Our observations propose C. caldarium as a primitive Rhodophytan which is the "bridge" alga linking the prokaryotic blue-green and the red algae. some features of the Cyanidium chloroplast e.g. the single membrane enveloping the plastid, or the cyanobacterial nature of its thylakoids and other cellular characteristics, point to the primaeval status of this early-evolved eukaryote which is considered a "living fossil". It seems to be the true transitional organism between the anucleated and nucleated algae and is unlikely to be an endosymbiontic association of two or more cells, as speculated elsewhere.

Author: Rijgersberg, C. P.; Amesz, J.
Year: 1980
Title: Fluorescence and energy transfer in phycobiliprotein-containing algae at low temperature
Journal: Biochim Biophys Acta
Volume: 593
Issue: 2
Pages: 261-271
Date: Dec 3
Abstract: Fluorescence emission spectra of Anacystis nidulans, Porphyridium cruentum and Cyanidium caldarium, three phycobiliprotein-containing algae, were measured at temperatures between 4 and 120 K in the absence and in the presence of quinones as quenchers of chlorophyll fluorescence. In all species three major emission bands were observed in the chlorophyll a region, near 685 nm (F-685), 695 nm (F-695) and between 710 and 730 nm. Additional bands were observed at shorter wavelengths; these were preferentially excited by light absorbed by the phycobiliproteins and are presumably due to phycocyanins and allophycocyanins. The amplitudes of F-685, F-695 and the long-wave emission showed a distinct increase upon cooling. For F-685 and F-695 the temperature dependence was similar to that earlier observed with spinach chloroplasts, for the long-wave emission it appeared to depend on the location of the emission bands, which was different for different species. All three bands were strongly quenched by quinones. These and other data suggest that the origin of these bands is the same as in higher plants, and that the fluorescence increase upon cooling can be explained by a lowering of the efficiency of energy transfer between chlorophyll molecules. It is concluded that at most a small percentage of the emission at 685 nm can be ascribed to allophycocyanin B, and that the efficiency of energy transfer between allophycocyanin B and chlorophyll a probably exceeds 99% both at 77 and 4 K. Experiments with isolated phycobilisomes suggest that energy transfer from allophycocyanin to allophycocyanin B occurs with an efficiency of about 90% at low temperature. The effect of quenchers can be understood by the assumption that the quenching is caused by the formation of non-fluorescent traps in the bulk chlorophyll. Of three quinones tested, the strongest quenching was observed with dibromothymoquinone, which quenched F-685, F-695 and the long-wave emission approximately equally. Menadione and 1,4-naphthoquinone, however, preferentially quenched the long-wave bands, indicating a stronger interaction with Photosystem I than with Photosystem II chlorophylls.

Author: Rigano, C.; Vona, V.; Di Martino Rigano, V.; Fuggi, A.
Year: 1980
Title: Active and inactive nitrate reductase. Effects of mild treatment with denaturing agents of protein
Journal: Biochim Biophys Acta
Volume: 613
Issue: 1
Pages: 26-33
Abstract: Nitrate reductase (NAD(P)H:nitrate oxidoreductase, EC 1.6.6.2) of the unicellular alga Cyanidium caldarium can exist in two interconvertible forms; one catalytically active and one inactive. The inactive nitrate reductase can be activated by mild treatment with denaturing agents of protein. By treatment with urea or mersalyl, activation of both the NADPH and benzyl viologen activities can be realized under mild conditions, whereas by treatment with heat, the activation of benzyl viologen activity is concomitant with loss of the NADPH activity. On the other hand, both activities are activated and destroyed concomitantly by ethylene glycol. In the present of FAD, either activation of benzyl viologen activity or loss of NADPH activity upon heating occur only at higher temperatures. The existence of a controlling region in the nitrate reductase molecule is postulated.

Author: Brown, S. B.; Holroyd, A. J.; Troxler, R. F.
Year: 1980
Title: Mechanism of bile-pigment synthesis in algae. 18O incorporation into phycocyanobilin in the unicellular rhodophyte, Cyanidium caldarium
Journal: Biochem J
Volume: 190
Issue: 2
Pages: 445-449
Date: Aug 15
Abstract: The origin of the lactam oxygen atoms of phycocyanobilin from Cyanidium caldarium was studied using 18O labelling. By inhibiting photosynthesis, a high 18O enrichment was maintained in the gas phase and the resulting incorporation of label showed that the lactam oxygen atoms were derived from two oxygen molecules. Slow exchange of these oxygen atoms with water was demonstrated directly by using H218O.

Author: Troxler, R. F.; Brown, A. S.; Brown, S. B.
Year: 1979
Title: Bile pigment synthesis in plants. Mechanism of 18O incorporation into phycocyanobilin in the unicellular rhodophyte. Cyanidium caldarium
Journal: J Biol Chem
Volume: 254
Issue: 9
Pages: 3411-3418
Date: May 10

Author: Troxler, R. F.; Offner, G. D.
Year: 1979
Title: delta-Aminolevulinic acid synthesis in a Cyanidium caldarium mutant unable to make chlorophyll a and phycobiliproteins
Journal: Arch Biochem Biophys
Volume: 195
Issue: 1
Pages: 53-65
Date: Jun

Author: Ford, T. W.
Year: 1979
Title: Ribulose 1,5-bisphosphate carboxylase from the thermophilic, acidophilic alga, Cyanidium caldarium (Geitler). Purification, characterisation and thermostability of the enzyme
Journal: Biochim Biophys Acta
Volume: 569
Issue: 2
Pages: 239-248
Date: Aug 15
Abstract: An an initial stage in the study of proteins from thermophilic algae, the enzyme ribulose 1,5-bisphosphate carboxylase 2-phospho-D-glycerate carboxylyase (dimerizing, EC 4.1.1.39) was purified 11-fold from the thermophilic alga Cyandium caldarium, with a 24% recovery. This purified enzyme appeared homogeneous on polyacrylamide gels and could be dissociated into two subunit types of molecular weights 55,000 and 14,900. The optimal assay temperature was 42.5 degrees C, whilst enzyme purified from Chlorella spp. showed maximum activity at 35 degrees C. The thermostability of Cyanidium ribulose 1,5-bisphosphate carboxylase was considerably greater than that of the Chlorella enzyme, and the presence of Mg2+ and HCO-3 further enhanced this heat stability. A break in the Arrhenius plot occured at 20 degrees C for Chlorella ribulose 1,5-bisphosphate carboxylase and 36 degrees C for the enzyme from Cyanidium. It is suggested that the thermostability of Cyanidium ribulose 1,5-bisphosphate carboxylase is a result of an inherent stability of the enzyme molecule which permits efficient CO2 fixation at high temperatures but results in low activity in the mesophilic temperature range.

Author: Brown, A. S.; Offner, G. D.; Ehrhardt, M. M.; Troxler, R. F.
Year: 1979
Title: Phycobilin-apoprotein linkages in the alpha and beta subunits of phycocyanin from the unicellular rhodophyte, Cyanidium caldarium. Amino acid sequences of 35S-labeled chromopeptides
Journal: J Biol Chem
Volume: 254
Issue: 16
Pages: 7803-7811
Date: Aug 25

Author: Troxler, R. F.; Kelly, P.; Brown, S. B.
Year: 1978
Title: Phycocyanobilin synthesis in the unicellular rhodophyte Cyanidium caldarium
Journal: Biochem J
Volume: 172
Issue: 3
Pages: 569-576
Date: Jun 15
Abstract: Light is required for synthesis of the accessory photosynethetic pigment phycocyanin in cells of the unicellular rhodophyte Cyanidium caldarium. Phycocyanin is a conjugated protein composed of polypeptide subunits to which the light-absorbing bile pigment chromophore phycocyanobilin is covalently attached. Dark-grown cells of C. caldarium are unable to make phycocyanin, but when incubated in the dark with 5-aminolaevulinate the cells synthesize and excrete a protein-free phycobilin (algal bile pigment) into the suspending medium. The electronic absorption spectrum, electron impact mass spectrum, chromatographic properties and imide products obtained after chronic acid degradation of the excreted phycobilin were identical with those of phycocyanobilin cleaved from phycocyanin in boiling methanol. This establishes the structural identity between the excreted phycobilin, which is the end product of bile-pigment synthesis in vivo, and the chromophore cleaved from phycocyanin in boiling methanol. The significance of the structure of the excreted phycobilin with respect to the events surrounding the assembly of the phycocyanin molecule in vivo is discussed.

Author: De Luca, P.; Taddei, R.; Varano, L.
Year: 1978
Title: Cyanidioschyzon merolae: a new alga of thermal acidic environments.
Journal: Webbia
Volume: 33
Pages: 37-44

Author: Brock, T. D.
Year: 1978
Title: The genus Cyanidium
Editor: Brock, T. D.
Book Title: Thermophilic microorganisms and life at high temperatures.
City: New York
Publisher: Springer-Verlag
Pages: 255-302

Author: Bedord, C. J.; McMahon, V.; Adams, B.
Year: 1978
Title: alpha-linolenic acid biosynthesis in Cyanidium caldarium
Journal: Arch Biochem Biophys
Volume: 185
Issue: 1
Pages: 15-20
Date: Jan 15

Author: Rigano, C.; Aliotta, G.; Rigano, V. D.; Fuggi, A.; Vona, V.
Year: 1977
Title: Heterotrophic growth patterns in the unicellular alga Cyanidium caldarium. A possible role for threonine dehydrase
Journal: Arch Microbiol
Volume: 113
Issue: 3
Pages: 191-196
Date: Jun 20

Author: Ono, T. A.; Murata, N.
Year: 1977
Title: Temperature dependence on the delayed fluorescence of chlorophyll a in blue-green algae
Journal: Biochim Biophys Acta
Volume: 460
Issue: 2
Pages: 220-229
Date: May 11
Abstract: 1. The delayed fluorescence of chlorophyll a was measured with a phosphoroscope by changing the temperature in a range of room temperatures in intact cells of blue-green algae, Anacystis nidulans, two strains of Anabaena variabilis and Plectonema boryanum, and other kinds of algae, Cyanidium caldarium and Chlorella pyrenoidosa. The induction of delayed fluorescence remarkably depended on the temperature of measurment. Nevertheless, the induction pattern was characterized by three levels of intensity; the initial rise level at the onset of excitation light, the maximum level after a period of excitation and the steady-state level after 10 min of excitation. 2. In A. nidulans and a strain of A. variabilis grown at various temperatures, close relationship was found between the phase transition of membrane lipids and the initial rise and the steady-state levels of delayed fluorescence. The initial rise level showed the maximum at the temperature of phase transition between the liquid crystalline and the mixed solid-liquid crystalline states, The steady-state levels showed a remarkable change from a high in the liquid crystalline state to a low level in the mixed solid-liquid crystalline state. 3. The millisecond decay kinetics of the delayed fluorescence measured at the steady-state level in A. nidulans grown at 38 degrees C consisted of two components with different decay rates. The half-decay time of the fast component was about 0.17 ms and was constant throughout the temperature range of measurement. The half decay time of slow component ranged from 0.6 to 1.5 ms, depending on the temperature of measurment.

Author: Murata, N.; Fork, D. C.
Year: 1977
Title: Temperature dependence of the light-induced spectral shift of carotenoids in Cyanidium caldarium and higher plant leaves. Evidence for an effect of the physical phase of chloroplast membrane lipids on the permeability of the membrane to ions
Journal: Biochim Biophys Acta
Volume: 461
Issue: 3
Pages: 365-378
Date: Sep 14

Author: Cohen-Bazire, G.; Beguin, S.; Rimon, S.; Glazer, A. N.; Brown, D. M.
Year: 1977
Title: Physico-chemical and immunological properties of allophycocyanins
Journal: Arch Microbiol
Volume: 111
Issue: 3
Pages: 225-238
Date: Jan 11
Abstract: Allophycocyanins were purified from diverse cyanobacteria and one rhodophytan alga (Cyanidium caldarium). The native proteins are trimeric molecules with the structure (alpha beta)3. Representative native allophycocyanins and their alpha and beta subunits were characterized with respect to molecular weight, amino acid composition, isoelectric point, absorption and fluorescence spectra and immunological properties. All of the allophycocyanins studied were strikingly similar with respect to each of these properties. Renatured alpha and beta subunits of allophycocyanin were distinct immunologically from each other, and both cross-reacted with the antiserum to the native protein. Trimeric allophycocyanin was readily reconstituted from the purified alpha and beta subunits. Formation of hybrid allophycocyanins was demonstrated by direct isolation and characterization of the hybrid proteins and by immunological techniques. The results support the view that allophycocyanins are a highly conserved group of proteins.

Author: Brown, A. S.; Troxler, R. F.
Year: 1977
Title: Properties and N-terminal sequence of allophycocyanin from the unicellular rhodophyte Cyanidium caldarium
Journal: Biochem J
Volume: 163
Issue: 3
Pages: 571-581
Date: Jun 1
Abstract: Allophycocyanin from the unicellular rhodophyte Cyanidium caldarium was purified by (NH4)2SO4 fractionation and ion-exchange chromatography on brushite (calcium phosphate) columns and on DEAE-Sephadex A-25 columns. The specific absorption coefficient (A0.1%1cm) at 650nm of purified allophycocyanin was 6.35 in 0.05M-potassium phosphate buffer, pH7.0. Absorption maxima of allophycocyanin occurred at 650, 618 (shoulder), 350 and 275 nm. Circular-dichroic spectra displayed positive-ellipticity bands at 658 and 630 nm and a major negative-ellipticity band at 340nm. Computer analysis of the circular-dichroic spectrum of allophycocyanin from 207 to 243 nm indicated 42% alpha-helix and 58% beta-form. The estimated molecular weight of purified allophycocyanin on calibrated Sephadex G-200 columns at pH7.0. was 196000. Electrophoretic examination of allophycocyanin on sodium dodecyl sulphate/polyacrylamide gels revealed a single band with apparent mol.wt. 16000. The presence of two polypeptide subunits, with nearly the same molecular weight, was revealed on polyacrylamide gels by using a modified electrophoresis buffer. Spectral analysis of the allophycocyanin subunits resolved by ion-exchange chromatography on Bio-Rex 70 columns indicated that a single phycocyanobilin chromophore was present on each polypeptide chain. Treatment of allophycocyanin with 8M-urea (pH3.0) and subsequent removal of urea by dialysis against water yielded a derivative phycobiliprotein with spectroscopic characteristics similar to those of phycocyanin. The original allophycocyanin spectrum was regenerated after incubation in phosphate buffer, pH7.0. Automated sequences analysis of the N-terminus of allophycocyanin showed that (a) the sequences of the two subunits were different from one another and were different from the subunits of phycocyanin from the same alga, (b) the subunits occurred in a molar ratio of 1:1 and (c) the sequences homology at the N-terminus among alpha- and beta-subunits of allophycocyanin from blue-green and red algae approached 90%.

Author: Rigano, C.; Fuggi, A.; Martino, Di; Rigano, V.; Aliotta, G.
Year: 1976
Title: Studies on utilization of 2-ketoglutarate, glutamate and other amino acids by the unicellular alga Cyanidium caldarium
Journal: Arch Microbiol
Volume: 107
Issue: 2
Pages: 133-138
Date: Mar 19
Abstract: Two strains of Cyandium caladarium which possess different biochemical and nutritional characteristics were examined with respect to their ability to utilize amino acids or 2-ketoglutarate as substrates. One strain utilizes alanine, glutamate or aspartate as nitrogen sources, and glutamate, alanine, or 2-ketoglutarate as carbon and energy sources for growth in the dark. The growth rate in the dark on 2-ketoglutarate is almost twice as high or higher than that on glutamate or alanine. During growth or incubation of this alga on amino acids, large amounts of ammonia are formed; however, ammonia formation is strongly inhibited by 2-ketoglutarate. The capacity of the alga and develops fully only when the cells are grown or incubated in the presence of glutamate.

Author: Jurgenson, J. E.; Beale, S. I.; Troxler, R. F.
Year: 1976
Title: Biosynthesis of delta-aminolevulinic acid in the unicellular rhodophyte, cyanidium caldarium
Journal: Biochem Biophys Res Commun
Volume: 69
Issue: 1
Pages: 149-157
Date: Mar 8

Author: Troxler, R. F.; Foster, J. A.; Brown, A. S.; Franzblau, C.
Year: 1975
Title: The alpha and beta subunits of Cyanidium caldarium phycocyanin: properties and amino acid sequences at the amino terminus
Journal: Biochemistry
Volume: 14
Issue: 2
Pages: 268-274
Date: Jan 28
Abstract: Phycocyanin was isolated and purified from the unicellular alga, Cyanidium caldarium. Subunits were prepared on a Bio-Rex-70 column developed stepwise with urea solutions (pH 1.9). The alpha subunit eluted in 8 M urea and the beta subunit eluted in 9 M urea. The alpha and beta subunits displayed absorption maxima at 660, 354, and 277 nm in 8 M and 9 M urea. The alpha:beta ratio of total absorbance under the 660-nm peak was 0.56 suggesting an alpha:beta phycocyanobilin chromophore ration of 1:2. On calibrated sodium dodecyl sulfate gels, the alphs subunit had an estimated molecular weight of 15,500 plus or minus 1100 and the beta subunit has an estimated molecular weight of 18,300 plus or minus 300. Minimum molecular weights based on one histidine residue per subunit were 16,300 for the alpha subunit and 18,750 for the beta subunit. Phycocyanin displayed a single visible absorption maximum at 625 nm and two positive circular dichroic bands at 632 and 610 nm. The alpha and beta subunits displayed single visible absorption maxima at 618 and 600 nm and single positive circular dichroic peaks at 620 and 585 nm, respectively. Two-dimensional maps of tryptic digests of the alpha and beta subunits revealed distinct patterns of peptides each of which was consistent with the lysine and arginine composition of these polypeptides. Maps of tryptic digests of phycocyanin contained 25 major peptides (a total of 27 lysine and arginine residues). Automated sequence analysis of separated subunits revealed a 70% homology within the first 27 residues at the amino terminus of the alpha and beta subunits of C. caldarium phycocyanin.

Author: Rigano, C.; Aliotta, G.
Year: 1975
Title: Electron donors and inhibitors of nitrate reductase from Cyanidium caldarium
Journal: Biochim Biophys Acta
Volume: 384
Issue: 1
Pages: 37-45
Date: Mar 28
Abstract: Studies on nitrate reductase (NAD(P)H:nitrate oxidoreductases EC 1.6.6.2) of Cyanidium caldarium revealed that the enzyme is inhibited by excess of electron donor, NADPH, reduced benzylviologen and FMN. Also dithionite, used to reduce benzylviologen and FMN, inactivates nitrate reductase: however, FMN at an optimal concentration and nitrate, added before the dithionite, protect the enzyme against this inactivation. Cyanide, cyanate and carbamyl phosphate inhibit the enzyme competitively with respect to nitrate, and Ki values are reported. Organic mercurials, 0.1 mM, act preferentially on NADPH activity, whereas Ag+ and Hg-2+ at the same concentration inactivate 80--90% of the benzylviologen and FMN activities. ADP is very poor inhibitor. Urea 4 M in 2 h destroys 90% of the NADPH activity and only 30% of the benzylviologen and FMN activities. The apparent Km values for NADPH, benzylviologen, FMN and nitrate have been determined.

Author: Rigano, C.; Aliotta, G.; Rigano, V. D.
Year: 1975
Title: Observations on enzymes of ammonia assimilation in two different strains of Cyanidium caldarium
Journal: Arch Microbiol
Volume: 104
Issue: 3
Pages: 297-299
Date: Aug 28
Abstract: Two strains of Cyanidium caldarium, one able to utilize nitrate as a substrate, and the other not, were tested for the presence of enzymes of ammonia assimilation. The nitrate-assimilating strain exhibits glutamate dehydrogenase activity. By contrast, the other strain lacks glutamate dehydrogenase; it possesses high alanine dehydrogenase and L-alanine aminotransferase activities which suggest that this strain may incorporate ammonia through reductive amination of pyruvate and may form glutamate from 2-ketoglutarate by a transamination reaction with alanine. Neither strain reveals glutamate synthase activity. Both strains contain similar levels of glutamine synthetase.

Author: Kao, O. H.; Edwards, M. R.; Berns, D. S.
Year: 1975
Title: Physical-chemical properties of C-phycocyanin isolated from an acido-thermophilic eukaryote, Cyanidium caldarium
Journal: Biochem J
Volume: 147
Issue: 1
Pages: 63-70
Date: Apr
Abstract: C-Phycocyanin from an acido-thermophilic eukaryotic alga, Cyanidium caldarium, was characterized with respect to subunit structure, absorption spectrum and fluorescence properties and was found to be similar to C-phycocyanins from mesophilic sources. The pH-dependence of fluorescence polarization and the changes in sedimentation velocity as a function of pH, concentration and temperature indicate the presence of extremely large amounts of unusually stable 19S aggregates. It was not possible to disaggregate this phycocyanin completely to monomer under normal conditions. The amino acid composition is similar to that of phycocyanins from other thermophilic and halophilic sources. The isoelectric point of this C-phycocyanin was 5.11, an unusually high value. The properties of this C-phycocyanin suggest an increase in protein stability as its mode of adaptation to the environmental stress of high temperature.

Author: Troxler, R. F.; Brown, A. S.
Year: 1974
Title: Metabolism of L-azetidine-2-carboxylic acid in the alga Cyanidium caldarium
Journal: Biochim Biophys Acta
Volume: 366
Issue: 3
Pages: 341-349
Date: Oct 28

Author: Rigano, C.; Aliotta, G.; Violante, U.
Year: 1974
Title: Reversible inactivation by ammonia of assimilatory nitrate reductase in Cyanidium caldarium
Journal: Arch Microbiol
Volume: 99
Issue: 1
Pages: 81-90

Author: Rigano, C.; Violante, U.
Year: 1973
Title: Effect of nitrate, ammonia and nitrogen starvation on the regulation of nitrate reductase in Cyanidium caldarium
Journal: Arch Mikrobiol
Volume: 90
Issue: 1
Pages: 27-33
Date: Mar 2

Author: Rigano, C.; Violante, U.; Aliotta, G.
Year: 1973
Title: Kinetic aspects of nitrate reductase from Cyanidium caldarium. Inhibition by reduced pyridine nucleotides
Journal: Biochim Biophys Acta
Volume: 327
Issue: 1
Pages: 19-23
Date: Nov 15

Author: Diner, B.; Mauzerall, D.
Year: 1973
Title: Photosynthetic oxygen production and the size of the photosynthetic unit in a cellfree preparation from cyanidium caldarium
Journal: Biochim Biophys Acta
Volume: 292
Issue: 1
Pages: 285-290
Date: Jan 18

Author: Troxler, R. F.
Year: 1972
Title: Synthesis of bile pigments in plants. Formation of carbon monoxide and phycocyanobilin in wild-type and mutant strains of the alga, Cyanidium caldarium
Journal: Biochemistry
Volume: 11
Issue: 23
Pages: 4235-4242
Date: Nov 7

Author: Seckbach, J.
Year: 1972
Title: On the fine structure of the acidophilic hot-spring alga Cyanidium caldarium: a taxonomic approach
Journal: Microbios
Volume: 5
Issue: 18
Pages: 133-142
Date: Mar-Apr

Author: Rigano, C.; Violante, U.
Year: 1972
Title: Comparative growth of the thermal algae Cyanidium caldarium on nitrate and ammonia at different temperatures
Journal: Arch Mikrobiol
Volume: 85
Issue: 1
Pages: 13-18

Author: Rigano, C.; Violante, U.
Year: 1972
Title: Effect of heat treatment on the activity in vitro of nitrate reductase from Cyanidium caldarium
Journal: Biochim Biophys Acta
Volume: 256
Issue: 2
Pages: 524-532
Date: Feb 28

Author: Gerasimenko, L. M.; Pusheva, M. A.; Goriunova, S. V.
Year: 1972
Title: Growth cycle and ultrafine structure of Cyanidium caldarium
Journal: Mikrobiologiia
Volume: 41
Issue: 2
Pages: 324-326
Date: Mar-Apr

Author: Rigano, C.
Year: 1971
Title: Studies on nitrate reductase from Cyanidium caldarium
Journal: Arch Mikrobiol
Volume: 76
Issue: 3
Pages: 265-276

Author: Doemel, W. N.; Brock, T. D.
Year: 1971
Title: The physiolocial ecology of Cyanidium caldarium.
Journal: J Gen Microbiol
Volume: 67
Pages: 17-32

Author: Adams, B. L.; McMahon, V.; Seckbach, J.
Year: 1971
Title: Fatty acids in the thermophilic alga, Cyanidium caldarium
Journal: Biochem Biophys Res Commun
Volume: 42
Issue: 3
Pages: 359-365
Date: Feb 5

Author: Doemel, W. N.; Brock, T. D.
Year: 1970
Title: The upper temperature limit of Cyanidium caldarium
Journal: Arch Mikrobiol
Volume: 72
Issue: 4
Pages: 326-332

Author: Staehelin, L. A.
Year: 1968
Title: Ultrastructural changes of the plasmalemma and the cell wall during the life cycle of Cyanidium caldarium
Journal: Proc R Soc Lond B Biol Sci
Volume: 171
Issue: 23
Pages: 249-259
Date: Nov 5

Author: Bailey, R. W.; Staehelin, L. A.
Year: 1968
Title: The chemical composition of isolated cell walls of Cyanidium caldarium
Journal: J Gen Microbiol
Volume: 54
Issue: 2
Pages: 269-276
Date: Dec

Author: Troxler, R. F.; Bogorad, L.
Year: 1966
Title: Studies on the formation of phycocyanin, porphyrins, and a blue phycobilin by wild-type and mutant strains of Cyanidium caldarium
Journal: Plant Physiol
Volume: 41
Issue: 3
Pages: 491-499
Date: Mar

Author: Lingens, F.; Heilmann, H. D.
Year: 1966
Title: [On the biosynthesis of lysine in Xanthomonas pruni, Streptomyces antibioticus and Cyanidium caldarium]
Journal: Hoppe Seylers Z Physiol Chem
Volume: 345
Issue: 4
Pages: 249-256

Author: Mercer, F. V.; Bogorad, L.; Mullens, R.
Year: 1962
Title: Studies with Cyanidium caldarium. I. The fine structure and systematic position of the organism
Journal: J Cell Biol
Volume: 13
Pages: 393-403
Date: Jun

Author: Nichols, K. E.; Bogorad, L.
Year: 1960
Title: Studies on phycobilin formation with mutants of Cyanidium caldarium
Journal: Nature
Volume: 188
Pages: 870-872
Date: Dec 3

Author: Allen, M. B.
Year: 1959
Title: Studies with Cyanidium caldarium, an anomalously pigmented chlorophyte
Journal: Arch Mikrobiol
Volume: 32
Issue: 3
Pages: 270-277

Author: Ciniglia, C.; Yoon, H. S.; Pollio, A.; Pinto, G.; Bhattacharya, D.
Year: 2004
Title:
Hidden biodiversity of the extremophilic Cyanidiales red algae
Journal: Mol Ecol
Volume: 13
Issue: 7
Pages: 1827-1838
Date: Jul
Abstract: Abstract The Cyanidiales is a group of asexual, unicellular red algae, which thrive in acidic and high temperature conditions around hot springs. These unicellular taxa have a relatively simple morphology and are currently classified into three genera, Cyanidium, Cyanidioschyzon and Galdieria. Little is known, however, about the biodiversity of Cyanidiales, their population structure and their phylogenetic relationships. Here we used a taxonomically broadly sampled three-gene data set of plastid sequences to infer a robust phylogenetic framework for the Cyanidiales. The phylogenetic analyses support the existence of at least four distinct Cyanidiales lineages: the Galdieria spp. lineage (excluding Galdieria maxima), the Cyanidium caldarium lineage, a novel monophyletic lineage of mesophilic Cyanidium spp. and the Cyanidioschyzon merolae plus Galdieria maxima lineage. Our analyses do not support the notion of a mesophilic ancestry of the Cyanidiales and suggest that these algae were ancestrally thermo-acidotolerant. We also used environmental polymerase chain reaction (PCR) for the rbcL gene to sample Cyanidiales biodiversity at five ecologically distinct sites at Pisciarelli in the Phlegrean Fields in Italy. This analysis showed a high level of sequence divergence among Cyanidiales species and the partitioning of taxa based on environmental conditions. Our research revealed an unexpected level of genetic diversity among Cyanidiales that revises current thinking about the phylogeny and biodiversity of this group. We predict that future environmental PCR studies will significantly augment known biodiversity that we have discovered and demonstrate the Cyanidiales to be a species-rich branch of red algal evolution.

Author: Minoda, A.; Sakagami, R.; Yagisawa, F.; Kuroiwa, T.; Tanaka, K.
Year: 2004
Title: Improvement of Culture Conditions and Evidence for Nuclear Transformation by Homologous Recombination in a Red Alga, Cyanidioschyzon merolae 10D
Journal: Plant Cell Physiol
Volume: 45
Issue: 6
Pages: 667-671
Date: Jun 15
Abstract: Although the nuclear genome sequence of Cyanidioschyzon merolae 10D, a unicellular red alga, was recently determined, DNA transformation technology that is important as a model plant system has never been available thus far. In this study, improved culture conditions resulted in a faster growth rate of C. merolae in liquid medium (doubling time = 9.2 h), and colony formation on gellan gum plates. Using these conditions, spontaneous mutants (5-fluoroortic acid resistant) deficient in the UMP synthase gene were isolated. The lesions were then restored by introducing the wild-type UMP synthase gene into the cells suggesting DNA transformation by homologous recombination.

Author: Nishida, K.; Misumi, O.; Yagisawa, F.; Kuroiwa, H.; Nagata, T.; Kuroiwa, T.
Year: 2004
Title: Triple Immunofluorescent Labeling of FtsZ, Dynamin, and EF-Tu Reveals a Loose Association Between the Inner and Outer Membrane Mitochondrial Division Machinery in the Red Alga Cyanidioschyzon merolae
Journal: J Histochem Cytochem
Volume: 52
Issue: 7
Pages: 843-849
Date: Jul
Abstract: In the mitochondria of primitive eukaryotes, FtsZ and dynamin are part of the machinery involved in division of the inner and outer membranes, respectively. These genes also commonly function in the same manner during chloroplast division. In this study, a relationship between the localization of the inner and outer division machinery was directly shown for the first time. Triple immunofluorescent labeling was performed in the red alga Cyanidioschyzon merolae by a device using narrow bandpass filter sets and bright photostable dyes. FtsZ (CmFtsZ1) and dynamin (CmDnm1) localizations were examined simultaneously throughout the mitochondrial division cycle with an alternative mitochondrial marker protein, the mitochondrial translation elongation factor EF-Tu, whose localization was also shown to be identical to the mitochondrial matrix. FtsZ and dynamin did not necessarily co-localize when both were recruited to the mitochondrial constriction site, indicating that inner and outer dividing machineries are not in tight association during the late stage of division.

Author: Weber APM, Oesterhelt C, Gross W, Brautigam A, Imboden LA, Krassovskaya I, Linka N, Truchina J, Schneidereit J, Voll H, Voll LM, Zimmermann M, Jamai A, Riekhof WR, Yu B, Garavito RM, Benning C.
Year: 2004
Title: EST-analysis of the thermo-acidophilic red microalga Galdieria sulphuraria reveals potential for lipid A biosynthesis and unveils the pathway of carbon export from rhodoplasts.
Journal: Plant Mol Biol
Volume: 55
Issue: 1
Pages: 17-32
Date: May
Abstract: When we think of extremophiles, organisms adapted to extreme environments, prokaryotes come to mind first. However, the unicellular red micro-alga Galdieria sulphuraria (Cyanidiales) is a eukaryote that can represent up to 90% of the biomass in extreme habitats such as hot sulfur springs with pH values of 0-4 and temperatures of up to 56 degrees C. This red alga thrives autotrophically as well as heterotrophically on more than 50 different carbon sources, including a number of rare sugars and sugar alcohols. This biochemical versatility suggests a large repertoire of metabolic enzymes, rivaled by few organisms and a potentially rich source of thermo-stable enzymes for biotechnology. The temperatures under which this organism carries out photosynthesis are at the high end of the range for this process, making G. sulphuraria a valuable model for physical studies on the photosynthetic apparatus. In addition, the gene sequences of this living fossil reveal much about the evolution of modern eukaryotes. Finally, the alga tolerates high concentrations of toxic metal ions such as cadmium, mercury, aluminum, and nickel, suggesting potential application in bioremediation. To begin to explore the unique biology of G. sulphuraria , 5270 expressed sequence tags from two different cDNA libraries have been sequenced and annotated. Particular emphasis has been placed on the reconstruction of metabolic pathways present in this organism. For example, we provide evidence for (i) a complete pathway for lipid A biosynthesis; (ii) export of triose-phosphates from rhodoplasts; (iii) and absence of eukaryotic hexokinases. Sequence data and additional information are available at http://genomics.msu.edu/galdieria.