title: The High Light Response and Redox Control of Thylakoid FtsH Protease in Chlamydomonas reinhardtii.
abstract: In Chlamydomonas reinhardtii, the major protease involved in the maintenance of photosynthetic machinery in thylakoid membranes, the FtsH protease, mostly forms large hetero-oligomers (∼1 MDa) comprising FtsH1 and FtsH2 subunits, whatever the light intensity for growth. Upon high light exposure, the FtsH subunits display a shorter half-life, which is counterbalanced by an increase in FTSH1/2 mRNA levels, resulting in the modest upregulation of FtsH1/2 proteins. Furthermore, we found that high light increases the protease activity through a hitherto unnoticed redox-controlled reduction of intermolecular disulfide bridges. We isolated a Chlamydomonas FTSH1 promoter-deficient mutant, ftsh1-3, resulting from the insertion of a TOC1 transposon, in which the high light-induced upregulation of FTSH1 gene expression is largely lost. In ftsh1-3, the abundance of FtsH1 and FtsH2 proteins are loosely coupled (decreased by 70% and 30%, respectively) with no formation of large and stable homo-oligomers. Using strains exhibiting different accumulation levels of the FtsH1 subunit after complementation of ftsh1-3, we demonstrate that high light tolerance is tightly correlated with the abundance of the FtsH protease. Thus, the response of Chlamydomonas to light stress involves higher levels of FtsH1/2 subunits associated into large complexes with increased proteolytic activity.
authors.affiliation: Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, Paris 75005, France.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, Paris 75005, France.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Qi
authors.affiliation: Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, Paris 75005, France.
authors.forename: Alizée
authors.initials: A
authors.lastname: Malnoë
authors.affiliation: Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, Paris 75005, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Choquet
authors.affiliation: Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, Paris 75005, France.
authors.forename: Francis-André
authors.initials: FA
authors.lastname: Wollman
authors.affiliation: Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, Paris 75005, France. Electronic address: catherine.devitry@ibpc.fr.
authors.forename: Catherine
authors.initials: C
authors.lastname: de Vitry
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D045726:Metalloproteases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D013489:Suppression, Genetic; D060431:Thylakoid Membrane Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D020033:Protein Isoforms; D060431:Thylakoid Membrane Proteins; D045726:Metalloproteases
keywords: Chlamydomonas reinhardtii; chloroplast protease; photoinhibition; regulation of gene expression