tailieunhanh - Báo cáo khóa học: A single mutation that causes phosphatidylglycerol deficiency impairs synthesis of photosystem II cores in Chlamydomonas reinhardtii

Two mutants ofChlamydomonas reinhardtii, mf1andmf2, characterized by a marked reduction in their phosphatidyl-glycerol content together with a complete loss in itsD 3 -trans hexadecenoic acid-containing form, also lost photosystemII (PSII) activity. Genetic analysis of crosses betweenmf2and wild-type strains shows a strict cosegregationof thePSII 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 | Eur. J. Biochem. 271 329-338 2004 FEBS 2003 doi A single mutation that causes phosphatidylglycerol deficiency impairs synthesis of photosystem II cores in Chlamydomonasreinhardtii Bernard Pineau1 Jacaueline Girard-Bascou2. Stenhan Eberhard2 Yves Choauet2 Antoine Trémolières1 Catherine Gerard-Hirne1 Annick Bennardo-Connan1 Paulette Decottignies3 Sylvie Gillet3 and Francis-Andre Wollman2 1Centre National de la Recherche Scientifique-Universite Paris-Sud UMR 8618 Institut de Biotechnologie desplantes Orsay France 2Centre National de la Recherche Scientifique UPR 1261 ass. University Paris VI Institut de Biologie Physico-Chimique Paris France 3Centre National de la Recherche Scientifique-Universite Paris XI UMR 8619 Institut de Biochimie et Biophysique Moleculaire et Cellulaire Orsay France Two mutants of Chlamydomonas reinhardtii mf1 and mf2 characterized by a marked reduction in their phosphatidylglycerol content together with a complete loss in its AỈ-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. Keywords photosystem II phosphatidylglycerol D1 synthesis Chlamydomonas thylakoid. The utilization of light energy during photosynthesis to split water molecules and