Functional Accumulation of Antenna Proteins in Chlorophyll b-Less Mutants of Chlamydomonas reinhardtii

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• 作者：Sandrine Bujaldon¹ ; ⁵ ; Natsumi Kodama² ; ³ ; ⁵ ; Fabrice Rappaport¹ ; ⁶ ; Rajagopal Subramanyam⁴ ; Catherine de Vitry¹ ; Yuichiro Takahashi² ; ³ ; ^{taka@cc.okayama-u.ac.jp} ; Francis-André ; Wollman¹ ; ^{wollman@ibpc.fr}
• 关键词：Chlamydomonas reinhardtii ; chlorophyll b-less mutant ; antenna protein ; CAO gene
• 刊名：Molecular Plant
• 出版年：2017
• 出版时间：9 January 2017
• 年：2017
• 卷：10
• 期：1
• 页码：115-130
• 全文大小：1972 K
• 卷排序：10

文摘

The green alga Chlamydomonas reinhardtii contains several light-harvesting chlorophyll a/b complexes (LHC): four major LHCIIs, two minor LHCIIs, and nine LHCIs. We characterized three chlorophyll b-less mutants to assess the effect of chlorophyll b deficiency on the function, assembly, and stability of these chlorophyll a/b binding proteins. We identified point mutations in two mutants that inactivate the CAO gene responsible for chlorophyll a to chlorophyll b conversion. All LHCIIs accumulated to wild-type levels in a CAO mutant but their light-harvesting function for photosystem II was impaired. In contrast, most LHCIs accumulated to wild-type levels in the mutant and their light-harvesting capability for photosystem I remained unaltered. Unexpectedly, LHCI accumulation and the photosystem I functional antenna size increased in the mutant compared with in the wild type when grown in dim light. When the CAO mutation was placed in a yellow-in-the-dark background (yid-BF3), in which chlorophyll a synthesis remains limited in dim light, accumulation of the major LHCIIs and of most LHCIs was markedly reduced, indicating that sustained synthesis of chlorophyll a is required to preserve the proteolytic resistance of antenna proteins. Indeed, after crossing yid-BF3 with a mutant defective for the thylakoid FtsH protease activity, yid-BF3-ftsh1 restored wild-type levels of LHCI, which defines LHCI as a new substrate for the FtsH protease.