Partial suppression of the respiratory defect of qrs1/her2 glutamyl-tRNA amidotransferase mutants by overexpression of the mitochondrial pentatricopeptide Msc6p
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Recently, a large body of evidences indicates the existence in the mitochondrial matrix of foci that contain different proteins involved in mitochondrial RNA metabolism. Some of these proteins have a pentatricopeptide repeat motif that constitutes their RNA-binding structures. Here we report that MSC6, a mitochondrial pentatricopeptide protein of unknown function, is a multi copy suppressor of mutations in QRS1/HER2 a component of the trimeric complex that catalyzes the transamidation of glutamyl-tRNAQ to glutaminyl-tRNAQ. This is an essential step in mitochondrial translation because of the lack of a specific mitochondrial aminoacyl glutaminyl-tRNA synthetase. MSC6 over-expression did not abolish translation of an aberrant variant form of Cox2p detected in QRS1/HER2 mutants, arguing against a suppression mechanism that bypasses Qrs1p function. A slight decrement of the mitochondrial translation capacity as well as diminished growth on respiratory carbon sources media for respiratory activity was observed in the msc6 null mutant. Additionally, the msc6 null mutant did not display any impairment in RNA transcription, processing or turnover. We concluded that Msc6p is a mitochondrial matrix protein and further studies are required to indicate the specific function of Msc6p in mitochondrial translation.
We thank Dr. Alexander Tzagoloff (Columbia University) for the critic review of the manuscript and helpful comments. This work was supported by grants and fellowships from Fundação de Amparo a Pesquisa de São Paulo (FAPESP—2013/09482-8), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq 302935/2014-2). Bruno Moda is a fellowship recipient from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).
- Araiso Y, Huot JL, Sekiguchi T, Frechin M, Fischer F, Enkler L, Senger B, Ishitani R, Becker HD, Nureki O (2014) Crystal structure of Saccharomyces cerevisiae mitochondrial GatFAB reveals a novel subunit assembly in tRNA-dependent amidotransferases. Nucleic Acids Res 42:6052–6063CrossRefPubMedPubMedCentralGoogle Scholar
- Botstein D, Davis RW (1982) The molecular biology of the yeast Saccharomyces cerevisiae: metabolism and gene expression. In: Strathern JN, Jones EW, Broach JR (eds) pp 607–636, Cold Spring Harbor Laboratory, Cold Spring Harbor, NYGoogle Scholar
- Faye G, Kujawa C, Fukuhara H (1974) Physical and genetic organization of petite and grande yeast mitochondrial DNA: iV. †† Paper III in this series is Michel et al. 1974. In vivo transcription products of mitochondrial DNA and localization of 23 S ribosomal RNA in petite mutants of Saccharo. J Mol Biol 88:185–203CrossRefPubMedGoogle Scholar
- Kehrein K, Schilling R, Möller-Hergt BV, Wurm CA, Jakobs S, Lamkemeyer T, Langer T, Ott M (2015b) Organization of mitochondrial gene expression in two distinct ribosome-containing assemblies. Cell Rep 10:843–853Google Scholar
- Tavares-Carreón F, Camacho-Villasana Y, Zamudio-Ochoa A, Shingú-Vázquez M, Torres-Larios A, Pérez-Martínez X (2008) The pentatricopeptide repeats present in Pet309 are necessary for translation but not for stability of the mitochondrial COX1 mRNA in yeast. J Biol Chem 283:1472–1479CrossRefPubMedGoogle Scholar