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  • 1
    Electronic Resource
    Electronic Resource
    The 1.5-.ANG. crystal structure of plastocyanin from the green alga Chlamydomonas reinhardtii (1993)
    s.l. : American Chemical Society
    Biochemistry 32 (1993), S. 10560-10567 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00091a005
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation, purification, and characterization of coupling factor 1 from Chlamydomonas reinhardi (1981)
    s.l. : American Chemical Society
    Biochemistry 20 (1981), S. 5476-5482 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00522a020
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  • 3
    Electronic Resource
    Electronic Resource
    POSTTRANSLATIONAL ASSEMBLY OF PHOTOSYNTHETIC METALLOPROTEINS (1998)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology and Plant Molecular Biology 49 (1998), S. 25-51 
    Details
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract The assembly of chloroplast metalloproteins requires biochemical catalysis. Assembly factors involved in the biosynthesis of metalloproteins might be required to synthesize, chaperone, or transport the cofactor; modify or chaperone the apoprotein; or catalyze cofactor-protein association. Genetic and biochemical approaches have been applied to the study of the assembly of chloroplast iron-sulfur centers, cytochromes, plastocyanin, and the manganese center of photosystem II. These have led to the discovery of NifS-homologues and cysteine desulfhydrase for iron-sulfur center assembly, six loci (CCS1-CCS5, ccsA) for c-type cytochrome assembly, four loci for cytochrome b6 assembly (CCB1-CCB4), the CtpA protease, which is involved in pre-D1 processing, and the PCY2 locus, which is involved in holoplastocyanin accumulation. New assembly factors are likely to be discovered via the study of assembly-defective mutants of Arabidopsis, cyanobacteria, Chlamydomonas, maize, and via the functional analysis of candidate cofactor metabolizing components identified in the genome databases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.arplant.49.1.25
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  • 4
    Electronic Resource
    Electronic Resource
    Mmicular mechanisms of cytochrome c biogenesis: three distinct systems (1998)
    Oxford BSL : Blackwell Science Ltd, UK
    Molecular microbiology 29 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The past 10 years have heralded remarkable progress in the understanding of the biogenesis of c-type cytochromes. The hallmark of c-type cytochrome synthesis is the covalent ligation of haem vinyl groups to two cysteinyl residues of the apocytochrome (at a Cys–Xxx–Yyy–Cys–His signature motif). From genetic, genomic and biochemical studies, it is clear that three distinct systems have evolved in nature to assemble this ancient protein. In this review, common principles of assembly for all systems and the mmicular mechanisms predicted for each system are summarized. Prokaryotes, plant mitochondria and chloroplasts use either system I or II, which are each predicted to use dedicated mechanisms for haem delivery, apocytochrome ushering and thioreduction. Accessory proteins of systems I and II co-ordinate the positioning of these two substrates at the membrane surface for covalent ligation. The third system has evolved specifically in mitochondria of fungi, invertebrates and vertebrates. For system III, a pivotal role is played by an enzyme called cytochrome c haem lyase (CCHL) in the mitochondrial intermembrane space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00869.x
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  • 5
    Electronic Resource
    Electronic Resource
    The biosynthesis of bacterial and plastidic c-type cytochromes (1994)
    Springer
    Photosynthesis research 40 (1994), S. 147-165 
    Details
    ISSN: 1573-5079
    Keywords: bacteria ; chloroplasts ; heme attachment ; mitochondria ; pre-protein maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The biosynthesis of bacterial and plastidic c-type cytochromes includes several steps that occur post-translationally. In the case of bacterial cytochromes, the cytosolically synthesized pre-proteins are translocated across the cytoplasmic membrane, the pre-proteins are cleaved to their mature forms and heme is ligated to the processed apoprotein. Although heme attachment has not been studied extensively at the biochemical level, molecular genetic approaches suggest that the reaction generally occurs after translocation of the apoprotein to the periplasm. Recent studies with Bradyrhizobium japonicum and Rhodobacter capsulatus indicate that the process of heme attachment requires the function of a large number of genes. Mutation of these genes generates a pleiotropic deficiency in all c-type cytochromes, suggesting that the gene products participate in processes required for the biosynthesis of all c-type cytochromes. In eukaryotic cells, the biosynthesis of photosynthetic c-type cytochromes is somewhat more complex owing to the additional level of compartmentation. Nevertheless, the basic features of the pathway appear to be conserved. For instance, as is the case in bacteria, translocation and processing of the pre-proteins is not dependent on heme attachment. Genetic analysis suggests that the nuclear as well as the plastid genomes encode functions required for heme attachment, and that these genes function in the biosynthesis of the membrane-associated as well as the soluble c-type cytochrome of chloroplasts. A feature of cytochromes c biogenesis that appears to be conserved between chloroplasts and mitochondria is the sub-cellular location of the heme attachment reaction (p-side of the energy transducing membrane). Continued investigation of all three experimental systems (bacteria, chloroplasts, mitochondria) is likely to lead to a greater understanding of the biochemistry of cytochrome maturation as well as the more general problem of cofactor-protein association during the assembly of an energy transducing membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019332
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  • 6
    Electronic Resource
    Electronic Resource
    Photosynthetic ATPases: purification, properties, subunit isolation and function (1985)
    Springer
    Photosynthesis research 6 (1985), S. 3-31 
    Details
    ISSN: 1573-5079
    Keywords: ATP ; ATPase ; Bacteria ; Coupling Factor ; Enzymes ; Geneties ; Photophosphorylation ; Plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic coupling factor ATPases (F1-ATPases) generally censist of five subunits named α, β, γ, δ and ε in order of decreasing apparent molecular weight. The isolated enzyme has a molecular weight of between 390,000 to 400,000, with the five subunits probably occurring in a 3:3:1:1:1 ratio. Some photosynthetic F1 ATPases are inactive as isolated and require treatment with protease, heat or detergent in order to elicit ATPase activity. This activity is sensitive to inhibition by free divalent cations and appears to be more specific for Ca2+ vs. Mg2+ as the metal ion substrate chelate. This preference for Ca2+ can be explained by the higher inhibition constant for inhibition of ATPase activity by free Ca2+. Methods for the assay of a Mg-dependent ATPase activity have recently been described. These depend on the presence of organic solvents or detergents in the reaction mixture for assay. The molecular mechanism behind the expression of either the Ca- or Mg-ATPase activities is unknown. F1-ATPases function to couple proton efflux from thylakoid membranes or chromatophores to ATP synthesis. The isolated enzyme may thus also be assayed for the reconstitution of ‘coupling activity’ to membranes depleted of coupling factor 1. The functions of the five subunits in the complex have been deduced from the results of chemical modification and reconstitution studies. The δ subunit is required for the functional binding of the F1 to the F0. The active site is probably contained in the β (and α) subunit(s). The proposed functions for the γ and ε subunits are, however, still matters of controversy. Coupling factors from a wide variety of species including bacteria, algae, C3 and C4 plants, appear to be immunologically related. The β subunits are the most strongly related, although the α and γ subunits also show significant immunological cross-reactivity. DNA sequence analyses of the genes for the β subunit of CF1 have indicated that the primary sequence of this polypeptide is highly conserved. The genes for the polypeptides of CF1 appear to be located in two cellular compartments. The α, β and ε subunits are coded for on chloroplast DNA, whereas the γ and δ subunits are probably nuclear encoded. Experiments involving protein synthesis by isolated chloroplasts or protein synthesis in the presence of inhibitors specific for one or the other set of ribosomes in the cell suggest the existence of pools of unassembled CF1 subunits. These pools, if they do exist in vivo, probably make up no greater than 1% of the total CF1 content of the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029044
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  • 7
    Electronic Resource
    Electronic Resource
    Plastocyanin: Structural and functional analysis (1994)
    Springer
    Journal of bioenergetics and biomembranes 26 (1994), S. 49-66 
    Details
    ISSN: 1573-6881
    Keywords: Cytochromef ; Photosystem-I ; blue-copper proteins ; cytochromec 6 ; electron transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Plastocyanin is one of the best characterized of the photosynthetic electron transfer proteins. Since the determination of the structure of poplar plastocyanin in 1978, the structure of algal (Scenedesmus, Enteromorpha, Chlamydomonas) and plant (French bean) plastocyanins has been determined either by crystallographic or NMR methods, and the poplar structure has been refined to 1.33 Å resolution. Despite the sequence divergence among plastocyanins of algae and vascular plants (e.g., 62% sequence identity between theChlamydomonas and poplar proteins), the three-dimensional structures are remarkably conserved (e.g., 0.76 Å rms deviation in the Cα positions between theChlamydomonas and poplar proteins). Structural features include a distorted tetrahedral copper binding site at one end of an eight-stranded antiparallel β-barrel, a pronounced negative patch, and a flat hydrophobic surface. The copper site is optimized for its electron transfer function, and the negative and hydrophobic patches are proposed to be involved in recognition of physiological reaction partners. Chemical modification, cross-linking, and site-directed mutagenesis experiments have confirmed the importance of the negative and hydrophobic patches in binding interactions with cytochromef and Photosystem I, and validated the model of two functionally significant electron transfer paths in plastocyanin. One putative electron transfer path is relatively short (∼4 Å) and involves the solvent-exposed copper ligand His-87 in the hydrophobic patch, while the other is more lengthy (∼12–15 Å) and involves the nearly conserved residue Tyr-83 in the negative patch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00763219
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  • 8
    Electronic Resource
    Electronic Resource
    Biosynthesis of cytochrome f in Chiamydomonas reinhardtii: analysis of the pathway in gabaculine-treated cells and in the heme attachment mutant B6 (1995)
    Springer
    Molecular genetics and genomics 246 (1995), S. 156-165 
    Details
    ISSN: 1617-4623
    Keywords: Chloroplast ; Cytochromes ; Gabaculine Heme ; Heme attachment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlamydomonas reinhardtii uses two c-type cytochromes for photosynthetic electron transfer: the thylakoid membrane-bound cytochrome f of the cytochrome b6f complex and the soluble cytochrome c6. Previously, a class of photosynthesis-minus, acetate-requiring mutants was identified which were deficient in both c-type cytochromes, and biochemical analyses of cytochrome c6 biosynthesis in these strains indicated that they were each blocked at the step of heme attachment to apocytochrome c6. In order to demonstrate that the deficiency in cytochrome f results from the same biochemical and genetic defect, cytochrome f biosynthesis was examined in the 136 mutant (a representative of this phenotypic class) and in spontaneous suppressor strains derived from 136. Pulse-radio-labeling experiments show that B6 synthesizes a form of cytochrome f that is rapidly degraded in vivo. This polypeptide is membrane associated and migrates with an electrophoretic mobility identical to that of standard apocytochrome f produced in vitro but slightly greater than that of standard holocytochrome f produced in vivo by wild-type cells. These findings suggest that the B6 strain is unable to convert apocytochrome f to holocytochrome f and that apocytochrome f is unstable in vivo. In the suppressed strains, accumulation of both holocytochrome f and holocytochrome c6 is restored. One suppressor mutation (strain B6R) displays uniparental inheritance whereas another (B6T3) displays Mendelian inheritance. In both cases, the three phenotypes, photosynthesis-plus, b6f + and cyt c6 + co-segregate in genetic crosses. This study therefore confirms that the dual cyt b6f/cytc6 − deficiency in B6 results from a single mutation that affects a step in holocytochrome formation that is common to the biosynthetic pathways of both plastidic c-type cytochromes. The study also confirms that pre-apocytochrome f synthesis, processing and association with the membrane is not dependent on heme attachment. Synthesis of cytochrome f does, however, appear to be dependent on heme availability. In cells depleted of tetrapyrrole pathway intermediates by gabaculine treatment, cytochrome f synthesis was significantly reduced. Since gabaculine treatment did not affect the stability of cytochrome f nor the accumulation of cytochrome f-encoding transcripts, the reduction is attributed to post-transcriptional regulation of preapocytochrome f synthesis via a pathway that is sensitive to the availability of heme or a tetrapyrrole pathway intermediate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294678
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  • 9
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    Chromosome-level genome assembly and transcriptome of the green alga Chromochloris zofingiensis illuminates astaxanthin production (2017)
    National Academy of Sciences
    Details
    Publication Date: 2017-05-08
    Description: Microalgae have potential to help meet energy and food demands without exacerbating environmental problems. There is interest in the unicellular green alga Chromochloris zofingiensis, because it produces lipids for biofuels and a highly valuable carotenoid nutraceutical, astaxanthin. To advance understanding of its biology and facilitate commercial development, we present a C. zofingiensis chromosome-level nuclear genome, organelle genomes, and transcriptome from diverse growth conditions. The assembly, derived from a combination of short- and long-read sequencing in conjunction with optical mapping, revealed a compact genome of ∼58 Mbp distributed over 19 chromosomes containing 15,274 predicted protein-coding genes. The genome has uniform gene density over chromosomes, low repetitive sequence content (∼6%), and a high fraction of protein-coding sequence (∼39%) with relatively long coding exons and few coding introns. Functional annotation of gene models identified orthologous families for the majority (∼73%) of genes. Synteny analysis uncovered localized but scrambled blocks of genes in putative orthologous relationships with other green algae. Two genes encoding beta-ketolase (BKT), the key enzyme synthesizing astaxanthin, were found in the genome, and both were up-regulated by high light. Isolation and molecular analysis of astaxanthin-deficient mutants showed that BKT1 is required for the production of astaxanthin. Moreover, the transcriptome under high light exposure revealed candidate genes that could be involved in critical yet missing steps of astaxanthin biosynthesis, including ABC transporters, cytochrome P450 enzymes, and an acyltransferase. The high-quality genome and transcriptome provide insight into the green algal lineage and carotenoid production.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Critical role ofChlamydomonas reinhardtiiferredoxin-5 in maintaining membrane structure and dark metabolism (2015)
    National Academy of Sciences
    Details
    Publication Date: 2015-11-16
    Description: Photosynthetic microorganisms typically have multiple isoforms of the electron transfer protein ferredoxin, although we know little about their exact functions. Surprisingly, aChlamydomonas reinhardtiimutant null for the ferredoxin-5 gene (FDX5) completely ceased growth in the dark, with both photosynthetic and respiratory functions severely compromised; growth in the light was unaffected. Thylakoid membranes in dark-maintainedfdx5mutant cells became severely disorganized concomitant with a marked decrease in the ratio of monogalactosyldiacylglycerol to digalactosyldiacylglycerol, major lipids in photosynthetic membranes, and the accumulation of triacylglycerol. Furthermore, FDX5 was shown to physically interact with the fatty acid desaturases CrΔ4FAD and CrFAD6, likely donating electrons for the desaturation of fatty acids that stabilize monogalactosyldiacylglycerol. Our results suggest that in photosynthetic organisms, specific redox reactions sustain dark metabolism, with little impact on daytime growth, likely reflecting the tailoring of electron carriers to unique intracellular metabolic circuits under these two very distinct redox conditions.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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