title: Characterization of Tbc2, a nucleus-encoded factor specifically required for translation of the chloroplast psbC mRNA in Chlamydomonas reinhardtii.
abstract: Genetic analysis has revealed that the three nucleus-encoded factors Tbc1, Tbc2, and Tbc3 are involved in the translation of the chloroplast psbC mRNA of the eukaryotic green alga Chlamydomonas reinhardtii. In this study we report the isolation and phenotypic characterization of two new tbc2 mutant alleles and their use for cloning and characterizing the Tbc2 gene by genomic complementation. TBC2 encodes a protein of 1,115 residues containing nine copies of a novel degenerate 38-40 amino acid repeat with a quasiconserved PPPEW motif near its COOH-terminal end. The middle part of the Tbc2 protein displays partial amino acid sequence identity with Crp1, a protein from Zea mays that is implicated in the processing and translation of the chloroplast petA and petD RNAs. The Tbc2 protein is enriched in chloroplast stromal subfractions and is associated with a 400-kD protein complex that appears to play a role in the translation of specifically the psbC mRNA.
authors.affiliation: Department of Molecular Biology and Department of Plant Biology, University of Geneva, 1211 Geneva 4, Switzerland.
authors.forename: Andrea H
authors.initials: AH
authors.lastname: Auchincloss
authors.forename: William
authors.initials: W
authors.lastname: Zerges
authors.forename: Karl
authors.initials: K
authors.lastname: Perron
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Girard-Bascou
authors.forename: Jean-David
authors.initials: JD
authors.lastname: Rochaix
mesh_terms: D000483:Alleles; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry; D002467:Cell Nucleus / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D015800:Protozoan Proteins / Q000737:chemistry* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D009687:Nuclear Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D010940:Plant Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; C459541:tbc2 protein, Chlamydomonas reinhardtii