The High Light Response and Redox Control of Thylakoid FtsH Protease in Chlamydomonas reinhardtii

作     者：Fei Wang Yafei Qi Alizee Malnoe Yves Choquet Francis-Andre Wollman 

作者机构：Institut de Biologie Physico-Chimique Unite Mixte de Recherche 7141 Centre National de la Recherche Scientifique/Universite Pierre et Marie Curie Paris 75005 France 

出 版 物：《Molecular Plant》 (分子植物（英文版）)

年 卷 期：2017年第10卷第1期

页      面：99-114页

核心收录：

学科分类：0710[理学-生物学] 071001[理学-植物学] 07[理学] 

基　　金：supported by basic funding from CNRS and UPMC 

主　　题：chloroplast protease regulation of gene expression photoinhibition Chlamydomonas reinhardtii 

摘      要：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 iso- lated 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 FtsH 1/2 subunits associated into large complexes with increased proteolytic activity.