title: Molecular cloning and nucleotide sequence of the nuclear PET122 gene required for expression of the mitochondrial COX3 gene in S. cerevisiae.
abstract: The nuclear PET122 gene from S. cerevisiae is necessary for translation of a single mitochondrial mRNA that encodes subunit III of cytochrome c oxidase. We report here the cloning and nucleotide sequence of PET122, and properties of the predicted protein product, which consists of 242 residues. Analysis of PET122-lacZ translational fusions confirms that the PET122 coding region is translated in vivo and indicates that the PET122 protein product is targeted to mitochondria. A 117 residue domain located in the carboxy-terminal half of the PET122 protein, at least part of which is shown by characterization of mutants to be critical for PET122 function, exhibits 24% identity and 59% similarity to a portion of the catalytic domain of E. coli alanyl-tRNA synthetase. However, pet122 mutants are not defective in mitochondrial translation per se, as would be expected if PET122 encoded a tRNA synthetase. Instead, the PET122 protein may carry out one or more activities in common with tRNA synthetases, such as binding of ATP or RNA.
authors.affiliation: Department of Microbiology, University of California, Los Angeles 90024.
authors.forename: J D
authors.initials: JD
authors.lastname: Ohmen
authors.forename: B
authors.initials: B
authors.lastname: Kloeckener-Gruissem
authors.forename: J E
authors.initials: JE
authors.lastname: McEwen
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D004272:DNA, Mitochondrial / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D005800:Genes, Fungal; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D014176:Protein Biosynthesis; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial; D046911:Macromolecular Substances; D003576:Electron Transport Complex IV