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Guillaume Allorent Ryutaro Tokutsu Thomas Roach Graham Peers Pierre Cardol Jacqueline Girard-Bascou Daphné Seigneurin-Berny Dimitris Petroutsos Marcel Kuntz Cécile Breyton Fabrice Franck Francis-André Wollman Krishna K. Niyogi Anja Krieger-Liszkay Jun Minagawa Giovanni Finazzi 《The Plant cell》2013,25(2):545-557
Absorption of light in excess of the capacity for photosynthetic electron transport is damaging to photosynthetic organisms. Several mechanisms exist to avoid photodamage, which are collectively referred to as nonphotochemical quenching. This term comprises at least two major processes. State transitions (qT) represent changes in the relative antenna sizes of photosystems II and I. High energy quenching (qE) is the increased thermal dissipation of light energy triggered by lumen acidification. To investigate the respective roles of qE and qT in photoprotection, a mutant (npq4 stt7-9) was generated in Chlamydomonas reinhardtii by crossing the state transition–deficient mutant (stt7-9) with a strain having a largely reduced qE capacity (npq4). The comparative phenotypic analysis of the wild type, single mutants, and double mutants reveals that both state transitions and qE are induced by high light. Moreover, the double mutant exhibits an increased photosensitivity with respect to the single mutants and the wild type. Therefore, we suggest that besides qE, state transitions also play a photoprotective role during high light acclimation of the cells, most likely by decreasing hydrogen peroxide production. These results are discussed in terms of the relative photoprotective benefit related to thermal dissipation of excess light and/or to the physical displacement of antennas from photosystem II. 相似文献
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Eberhard S Drapier D Wollman FA 《The Plant journal : for cell and molecular biology》2002,31(2):149-160
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Arthur R. Grossman Steven J. Karpowicz Mark Heinnickel David Dewez Blaise Hamel Rachel Dent Krishna K. Niyogi Xenie Johnson Jean Alric Francis-André Wollman Huiying Li Sabeeha S. Merchant 《Photosynthesis research》2010,106(1-2):3-17
Chlamydomonas reinhardtii, a unicellular green alga, has been exploited as a reference organism for identifying proteins and activities associated with the photosynthetic apparatus and the functioning of chloroplasts. Recently, the full genome sequence of Chlamydomonas was generated and a set of gene models, representing all genes on the genome, was developed. Using these gene models, and gene models developed for the genomes of other organisms, a phylogenomic, comparative analysis was performed to identify proteins encoded on the Chlamydomonas genome which were likely involved in chloroplast functions (or specifically associated with the green algal lineage); this set of proteins has been designated the GreenCut. Further analyses of those GreenCut proteins with uncharacterized functions and the generation of mutant strains aberrant for these proteins are beginning to unmask new layers of functionality/regulation that are integrated into the workings of the photosynthetic apparatus. 相似文献
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The three-dimensional structure of the cytochrome b(6)f complex disclosed the unexpected presence of a new heme c(i) [Stroebel, D., Choquet, Y., Popot, J.-L., and Picot, D. (2003) Nature 426, 413-418; Kurisu, G., Zhang, H., Smith, J. L., and Cramer, W. A. (2003) Science 302, 1009-1014]. Here we present a biochemical, spectroscopic, and mutagenesis study of this unusual heme binding in Chlamydomonas reinhardtii. As predicted by the structure data, we identify a Cys(35)-containing proteolytic fragment (Tyr(25)-Lys(111)) from cytochrome b(6) as a peptide that covalently binds a heme. Resonance Raman spectra of cyt b(6)f complexes show particular frequencies in nu(2), nu(3), nu(4), and nu(8) regions that identify this extra heme as a ferrous c'-like heme under a five-coordinated high-spin state. The set of frequencies is consistent with a coordination by either a water molecule or a hydroxide ion. Other changes in resonance Raman bands, observed in the mid- and low-frequency regions, point to a modification in conformation and/or environment of at least one b heme methyl and/or propionate group. Site-directed mutagenesis of apocytochrome b(6), leading to a Cys(35)Val substitution, generates Chlamydomonas strains that are unable to assemble cytochrome b(6)f complexes. On the basis of the mutant phenotype, we discuss the participation, in the covalent binding of heme c(i), of the nuclear CCB factors that we identified previously as controlling the apo to holo conversion of cytochrome b(6) [Kuras, R., de Vitry, C., Choquet, Y., Girard-Bascou, J., Culler, D., Büschlen, S., Merchant, S., and Wollman, F.-A. (1997) J. Biol. Chem. 272, 32427-32435]. 相似文献
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Chloroplast biogenesis of photosystem II cores involves a series of assembly-controlled steps that regulate translation
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The biogenesis of photosystem II, one of the major photosynthetic protein complexes, involves a cascade of assembly-governed regulation of translation of its major chloroplast-encoded subunits. In Chlamydomonas reinhardtii, the presence of the reaction center subunit D2 is required for the expression of the other reaction center subunit D1, while the presence of D1 is required for the expression of the core antenna subunit apoCP47. Using chimeric genes expressed in the chloroplast, we demonstrate that the decreased synthesis of D1 or apoCP47 in the absence of protein assembly is due to a genuine downregulation of translation. This regulation is mediated by the 5' untranslated region of the corresponding mRNA and originates from negative feedback exerted by the unassembled D1 or apoCP47 polypeptide. However, autoregulation of translation of subunit D1 is not implicated in the recovery from photoinhibition, which involves an increased translation of psbA mRNA in response to the degradation of photodamaged D1. De novo synthesis and repair of photosystem II complexes are independently controlled. 相似文献
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Bernard Pineau Jacqueline Girard-Bascou Stephan Eberhard Yves Choquet Antoine Trémolières Catherine Gérard-Hirne Annick Bennardo-Connan Paulette Decottignies Sylvie Gillet Francis-André Wollman 《European journal of biochemistry》2004,271(2):329-338
Two mutants of Chlamydomonas reinhardtii, mf1 and mf2, characterized by a marked reduction in their phosphatidylglycerol content together with a complete loss in its Delta3-trans hexadecenoic acid-containing form, also lost photosystem II (PSII) activity. Genetic analysis of crosses between mf2 and wild-type strains shows a strict cosegregation of the PSII and lipid deficiencies, while phenotypic analysis of phototrophic revertant strains suggests that one single nuclear mutation is responsible for the pleiotropic phenotype of the mutants. The nearly complete absence of PSII core is due to a severely decreased synthesis of two subunits, D1 and apoCP47, which is not due to a decrease in translation initiation. Trace amounts of PSII cores that were detected in the mutants did not associate with the light-harvesting chlorophyll a/b-binding protein antenna (LHCII). We discuss the possible role of phosphatidylglycerol in the coupled process of cotranslational insertion and assembly of PSII core subunits. 相似文献
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Anna Liponska Ailar Jamalli Richard Kuras Loreto Suay Enrico Garbe Francis-André Wollman Soumaya Laalami Harald Putzer 《Plant molecular biology》2018,96(6):641-653