intermolecular disulfide‐based light switch for chloroplast psbD gene expression in Chlamydomonas reinhardtii

• Published in: The Plant journal : for cell and molecular biology 2012-11, Vol.72 (3), p.378-389
• Main Authors: Schwarz, Christian, Bohne, Alexandra‐Viola, Wang, Fei, Cejudo, Francisco Javier, Nickelsen, Jörg
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Algae; Algal Proteins - genetics; Algal Proteins - metabolism; Biological and medical sciences; carbon; Chlamydomonas; Chlamydomonas reinhardtii; Chlamydomonas reinhardtii - genetics; Chlamydomonas reinhardtii - metabolism; Chlamydomonas reinhardtii - radiation effects; chloroplast gene expression; Chloroplast Proteins - genetics; Chloroplast Proteins - metabolism; Chloroplasts; Chloroplasts - metabolism; Cytochrome Reductases - metabolism; D2 protein; Darkness; disulfide bonds; Electrophoresis, Gel, Two-Dimensional; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Plant - genetics; genes; Light; Models, Molecular; Multiprotein Complexes; Nac2; Oxidation-Reduction; photosystem II; Photosystem II Protein Complex - genetics; Photosystem II Protein Complex - metabolism; Plant ecology; Plant physiology and development; Protein Binding; Protein Biosynthesis; Protein Interaction Mapping; Proteins; Recombinant Proteins; redox control; ribonucleoprotein particle; RNA; RNA-Binding Proteins - genetics; RNA-Binding Proteins - metabolism; size exclusion chromatography; Thioredoxins - metabolism
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2012.05083.x

Expression of the chloroplast psbD gene encoding the D2 protein of the photosystem II reaction center is regulated by light. In the green alga Chlamydomonas reinhardtii, D2 synthesis requires a high‐molecular‐weight complex containing the RNA stabilization factor Nac2 and the translational activator RBP40. Based on size exclusion chromatography analyses, we provide evidence that light control of D2 synthesis depends on dynamic formation of the Nac2/RBP40 complex. Furthermore, 2D redox SDS–PAGE assays suggest an intermolecular disulfide bridge between Nac2 and Cys11 of RBP40 as the putative molecular basis for attachment of RBP40 to the complex in light‐grown cells. This covalent link is reduced in the dark, most likely via NADPH‐dependent thioredoxin reductase C, supporting the idea of a direct relationship between chloroplast gene expression and chloroplast carbon metabolism during dark adaption of algal cells.