title: An yeast nuclear mutation conferring temperature-sensitivity to the mitochondrial tryptophanyl-tRNA synthetase.
abstract: The conditional respiratory-deficient Saccharomyces cerevisiae mutant pet-ts2281 was complemented by an yeast genomic DNA library. The gene thus isolated was sequenced and proved to be identical to the known MSW1 sequence encoding mitochondrial tryptophanyl-tRNA synthetase (Myers and Tzagoloff 1985). Compared to the wild-type, the ts2281 mutant allele of MSW1 contained a single T----C transition leading to a Leu----Ser replacement at position 294 of the protein sequence. In addition to this mutational alteration, our sequence data for the wild-type gene differ from the originally published MSW1 sequence at five other DNA positions which affect two locally restricted regions of the polypeptide chain. As expected, at the non-permissive temperature ts2281 cells are specifically defective in mitochondrial trp-tRNA formation and, thus, in overall mitochondrial protein synthesis. In addition, the patterns of cytochrome b mRNA maturation intermediates were distinctly different in ts2281 and wild-type yeast cells. The mutational effect of the observed amino-acid substitution in ts2281 is discussed in terms of weakened hydrogen bonding in the C-terminal half of the MSW1-encoded protein.
authors.affiliation: Lehrstuhl für Biochemie, Universität Erlangen-Nürnberg, Federal Republic of Germany.
authors.forename: R
authors.initials: R
authors.lastname: Entrup
authors.forename: W
authors.initials: W
authors.lastname: Langgut
authors.forename: T
authors.initials: T
authors.lastname: Lisowsky
authors.forename: E
authors.initials: E
authors.lastname: Schweizer
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D013696:Temperature; D014369:Tryptophan-tRNA Ligase / Q000235:genetics*
chemical_list: D014369:Tryptophan-tRNA Ligase