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

• Published in: The Journal of cell biology 1989-09, Vol.109 (3), p.991-1006
• Main Authors: Vitry, C. de (Institut de Biologie Physico-Chimique, Paris, France), Olive, J, Drapier, D, Recouvreur, M, Wollman, F.A
• Format: Article
• Language: English
• Subjects: ALGAE; ALGUE; Antibodies; Biological and medical sciences; BIOSINTESIS; BIOSYNTHESE; BIOSYNTHESIS; Cell structures and functions; Cells; Chlamydomonas - genetics; Chlamydomonas - metabolism; Chlamydomonas - ultrastructure; Chlorophyll - biosynthesis; Chlorophyll - genetics; Chlorophyll - isolation & purification; Chlorophyll - metabolism; Chlorophylls; Chloroplast, photosynthetic membrane and photosynthesis; Chloroplasts; CORE ANTENNA SUBUNIT; FOTOSINTESIS; Fundamental and applied biological sciences. Psychology; Gels; Intracellular Membranes - metabolism; Intracellular Membranes - ultrastructure; Kinetics; Light-Harvesting Protein Complexes; Macromolecular Substances; Molecular and cellular biology; MUTANT; MUTANTES; MUTANTS; Mutation; OXYGEN-EVOLVING ENHANCER SUBUNIT; P branes; Peptide Hydrolases - metabolism; Phosphorylation; PHOTOSYNTHESE; PHOTOSYNTHESIS; Photosynthetic Reaction Center Complex Proteins; Photosystem II; Photosystem II Protein Complex; Plant Proteins - biosynthesis; Plant Proteins - genetics; Plant Proteins - isolation & purification; PLASTE; PLASTIDIOS; PLASTIDS; Protein Processing, Post-Translational; PSII CORE SUBUNIT; String theory; Thylakoids
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.109.3.991

We studied the assembly of photosystem II (PSII) in several mutants from Chlamydomonas reinhardtii which were unable to synthesize either 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 electrophoretograms of cells pulse labeled with [14 C]acetate. Their accumulation in thylakoid membranes was studied on immunoblots, their chlorophyll-binding ability on nondenaturating gels, their assembly by detergent fractionation, their stability by pulse-chase experiments and determination of in vitro protease sensitivity, and their localization by immunocytochemistry. In Chlamydomonas, the PSII core subunits P5 (47 kD), D1, and D2 are synthesized in a concerted manner while P6 synthesis is independent. P5 and P6 accumulate independently of each other in the stacked membranes. They bind chlorophyll soon after, or concomitantly with, their synthesis and independently of the presence of the other PSII subunits. Resistance to degradation increases step by step: beginning with assembly of P5, D1, and D2, then with binding of P6, and, finally, with binding of the OEE subunits on two independent high affinity sites (one for OEE1 and another for OEE2 to which OEE3 binds). In the absence of PSII cores, the OEE subunits accumulate independently in the thylakoid lumen and bind loosely to the membranes; OEE1 was found on stacked membranes, but OEE2 was found on either stacked or unstacked membranes depending on whether or not P6 was synthesized.