title: The Cbp2 protein stimulates the splicing of the omega intron of yeast mitochondria.
abstract: The Cbp2 protein is encoded in the nucleus and is required for the splicing of the terminal intron of the mitochondrial COB gene in Saccharomyces cerevisiae . Using a yeast strain that lacks this intron but contains a related group I intron in the precursor of the large ribosomal RNA, we have determined that Cbp2 protein is also required for the normal accumulation of 21S ribosomal RNA in vivo . Such strains bearing a deletion of the CBP2 gene adapt slowly to growth in glycerol/ethanol media implying a defect in derepression. At physiologic concentrations of magnesium, Cbp2 stimulates the splicing of the ribosomal RNA intron in vitro . Nevertheless, Cbp2 is not essential for splicing of this intron in mitochondria nor is it required in vitro at magnesium concentrations >5 mM. A similar intron exists in the large ribosomal RNA (LSU) gene of Saccharomyces douglasii . This intron does need Cbp2 for catalytic activity in physiologic magnesium. Similarities between the LSU introns and COB intron 5 suggest that Cbp2 may recognize conserved elements of the these two introns, and protein-induced UV crosslinks occur in similar sites in the substrate and catalytic domains of the RNA precursors.
authors.affiliation: Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Box 100266, Gainesville, FL 32610, USA.
authors.forename: L C
authors.initials: LC
authors.lastname: Shaw
authors.forename: A S
authors.initials: AS
authors.lastname: Lewin
mesh_terms: D001059:Apoproteins / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D003573:Cytochrome b Group / Q000096:biosynthesis / Q000235:genetics; D045303:Cytochromes b; D005656:Fungal Proteins / Q000378:metabolism*; D005800:Genes, Fungal; D005838:Genotype; D007438:Introns; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010101:Oxygen Consumption; D012322:RNA Precursors / Q000378:metabolism*; D012326:RNA Splicing; D012331:RNA, Fungal / Q000378:metabolism; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012261:Ribonucleoproteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D014158:Transcription, Genetic
chemical_list: D001059:Apoproteins; C071249:CBP2 protein, S cerevisiae; D003573:Cytochrome b Group; D005656:Fungal Proteins; D012322:RNA Precursors; D012331:RNA, Fungal; D012335:RNA, Ribosomal; D012261:Ribonucleoproteins; D029701:Saccharomyces cerevisiae Proteins; D045303:Cytochromes b; D008274:Magnesium