Posttranslational events leading to the assembly of photosystem II protein complex: a study using photosynthesis mutants from Chlamydomonas reinhardtii

Abstract. We studied the assembly of photosystem II (PSII) in several mutants from Chlamydomonas rein-hardtii which were unable to synthesize ither one PSII core subunit (P6 [43 kD], D1, or D2) or one oxygen-evolving enhancer (OEE1 or OEE2) subunit. Synthesis of the PSII subunits was analyzed on elec-trophoretograms of cells pulse labeled with [14C]ace-tate. Their accumulation i thylakoid membranes was studied on immunoblots, their chlorophyll-binding ability on nondenaturating gels, their assembly by de-tergent fractionation, their stability by pulse-chase x-periments and determination of in vitro protease sensi-tivity, and their localization by immunocytochemistry. In Chlamydomonas, the PSII core subunits P5 (47 kD), D1, and D2 are synthesized in a concerted man