Isolation and Characterization of Photoautotrophic Mutants of <i>Chlamydomonas reinhardtii</i> Deficient in State Transition

Article Article scientifique Article Isolation and Characterization of Photoautotrophic Mutants of <i>Chlamydomonas reinhardtii</i> Deficient in State Transition eng 1999 author Fleischmann Mark Mike 28869 author Ravanel Stéphane 508170 author Delosme René author Olive Jacqueline author Zito Francesca author Wollman Francis-André author Rochaix Jean-David 25289 30987-30994 10.1074/jbc.274.43.30987 0021-9258 http://www.jbc.org/lookup/doi/10.1074/jbc.274.43.30987 In photosynthetic cells of higher plants and algae, the distribution of light energy between photosystem I and photosystem II is controlled by light quality through a process called state transition. It involves a reorganization of the light-harvesting complex of photosystem II (LHCII) within the thylakoid membrane whereby light energy captured preferentially by photosystem II is redirected toward photosystem I or vice versa. State transition is correlated with the reversible phosphorylation of several LHCII proteins and requires the presence of functional cytochrome b₆f complex. Most factors controlling state transition are still not identified. Here we describe the isolation of photoautotrophic mutants of the unicellular algaChlamydomonas reinhardtii, which are deficient in state transition. Mutant stt7 is unable to undergo state transition and remains blocked in state I as assayed by fluorescence and photoacoustic measurements. Immunocytochemical studies indicate that the distribution of LHCII and of the cytochrome b₆f complex between appressed and nonappressed thylakoid membranes does not change significantly during state transition in stt7, in contrast to the wild type. This mutant displays the same deficiency in LHCII phosphorylation as observed for mutants deficient in cytochrome b₆f complex that are known to be unable to undergo state transition. The stt7 mutant grows photoautotrophically, although at a slower rate than wild type, and does not appear to be more sensitive to photoinactivation than the wild-type strain. Mutant stt3-4b is partially deficient in state transition but is still able to phosphorylate LHCII. Potential factors affected in these mutant strains and the function of state transition in C. reinhardtii are discussed. Dewey 570 Dewey 580 Swiss National Science Foundation 31-50895.97 CH 43 Département de biologie moléculaire 161 45 Département des sciences végétales 163 false Journal of Biological Chemistry 274 43 675b3a64-ece5-4877-8762-f505bcaa6965 Article (Published version) Public JBC-1999-Fleischmann-30987-94.pdf 224179 application/pdf openAccess Faculté des sciences / Section de biologie / Département de biologie moléculaire Faculté des sciences / Section de biologie / Département des sciences végétales

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Isolation and Characterization of Photoautotrophic Mutants of Chlamydomonas reinhardtii Deficient in State Transition	Journal of Biological Chemistry			1999	341	328

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Ravanel, Stéphane