title: Glutamyl-tRNAGln amidotransferase is essential for mammalian mitochondrial translation in vivo.
abstract: Translational accuracy depends on the correct formation of aminoacyl-tRNAs, which, in the majority of cases, are produced by specific aminoacyl-tRNA synthetases that ligate each amino acid to its cognate isoaceptor tRNA. Aminoacylation of tRNAGln, however, is performed by various mechanisms in different systems. Since no mitochondrial glutaminyl-tRNA synthetase has been identified to date in mammalian mitochondria, Gln-tRNAGln has to be formed by an indirect mechanism in the organelle. It has been demonstrated that human mitochondria contain a non-discriminating glutamyl-tRNA synthetase and the heterotrimeric enzyme GatCAB (where Gat is glutamyl-tRNAGln amidotransferase), which are able to catalyse the formation of Gln-tRNAGln in vitro. In the present paper we demonstrate that mgatA (mouse GatA) interference in mouse cells produces a strong defect in mitochondrial translation without affecting the stability of the newly synthesized proteins. As a result, interfered cells present an impairment of the oxidative phosphorylation system and a significant increase in ROS (reactive oxygen species) levels. MS analysis of mitochondrial proteins revealed no glutamic acid found in the position of glutamines, strongly suggesting that misaminoacylated Glu-tRNAGln is rejected from the translational apparatus to maintain the fidelity of mitochondrial protein synthesis in mammals.
authors.forename: Lucía
authors.initials: L
authors.lastname: Echevarría
authors.forename: Paula
authors.initials: P
authors.lastname: Clemente
authors.forename: Rosana
authors.initials: R
authors.lastname: Hernández-Sierra
authors.forename: María Esther
authors.initials: ME
authors.lastname: Gallardo
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Fernández-Moreno
authors.forename: Rafael
authors.initials: R
authors.lastname: Garesse
mesh_terms: D000818:Animals; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics*; D019884:Nitrogenous Group Transferases / Q000235:genetics* / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010641:Phenotype; D014176:Protein Biosynthesis / Q000502:physiology*; D055550:Protein Stability; D017382:Reactive Oxygen Species / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D017382:Reactive Oxygen Species; D019884:Nitrogenous Group Transferases; C047694:glutamyl-tRNA(Gln) amidotransferase