title: Identification of an OPR protein involved in the translation initiation of the PsaB subunit of photosystem I.
abstract: Genetic analysis of mutants deficient in the biosynthesis of the photosystem I complex has revealed several nucleus-encoded factors that act at different post-transcriptional steps of chloroplast gene expression. Here we have identified and characterized the gene affected in the tab 1-F15 mutant, which is specifically deficient in the translation of the photosystem I reaction center protein PsaB as the result of a single nucleotide deletion. This gene encodes Tab 1, a 1287 amino acid protein that contains 10 tandem 38-40 amino acid degenerate repeats of the PPPEW/OPR (octatricopeptide repeat) family, first described for the chloroplast translation factor Tbc2. These repeats are involved in the binding of Tab 1 to the 5'-untranslated region of the psaB mRNA based on gel mobility shift assays. Tab 1 is part of a large family of proteins in Chlamydomonas that are also found in several bacteria and protozoans, but are rare in land plants.
authors: Departments of Molecular Biology and Plant Biology, University of Geneva, 30, Quai Ernest Ansermet, Geneva 1211, Switzerland.
authors: Michèle
authors: M
authors: Rahire
authors: Fabrice
authors: F
authors: Laroche
authors: Lorenzo
authors: L
authors: Cerutti
authors: Jean-David
authors: JD
authors: Rochaix
mesh_terms: D020121:5' Untranslated Regions; D000595:Amino Acid Sequence; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010442:Peptide Chain Initiation, Translational; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011132:Polyribosomes / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000032:analysis / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid
chemical_list: D020121:5' Untranslated Regions; D009687:Nuclear Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D016601:RNA-Binding Proteins; C089909:photosystem I, psaB subunit; C459541:tbc2 protein, Chlamydomonas reinhardtii