Mitochondrial and cytoplasmic isoleucyl-, glutamyl- and arginyl-tRNA synthetases of yeast are encoded by separate genes.
Three complementation groups of a pet mutant collection have been found to be composed of respiratory-deficient deficient mutants with lesions in mitochondrial protein synthesis. Recombinant plasmids capable of restoring respiration were cloned by transformation of representatives of each complementation group with a yeast genomic library. The plasmids were used to characterize the complementing genes and to institute disruption of the chromosomal copies of each gene in respiratory-proficient yeast. The sequences of the cloned genes indicate that they code for isoleucyl-, arginyl- and glutamyl-tRNA synthetases. The properties of the mutants used to obtain the genes and of strains with the disrupted genes indicate that all three aminoacyl-tRNA synthetases function exclusively in mitochondrial proteins synthesis. The ISM1 gene for mitochondrial isoleucyl-tRNA synthetase has been localized to chromosome XVI next to UME5. The MSR1 gene for the arginyl-tRNA synthetase was previously located on yeast chromosome VIII. The third gene MSE1 for the mitochondrial glutamyl-tRNA synthetase has not been localized. The identification of three new genes coding for mitochondrial-specific aminoacyl-tRNA synthetases indicates that in Saccharomyces cerevisiae at least 11 members of this protein family are encoded by genes distinct from those coding for the homologous cytoplasmic enzymes.
Tzagoloff
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Department of Biological Sciences, Columbia University, New York 10027, USA.
Shtanko
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D001126:Arginine-tRNA Ligase / Q000235:genetics*; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000201:enzymology; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D005975:Glutamate-tRNA Ligase / Q000235:genetics*; D007533:Isoleucine-tRNA Ligase / Q000235:genetics*; D008928:Mitochondria / Q000201:enzymology; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*
D005975:Glutamate-tRNA Ligase; D001126:Arginine-tRNA Ligase; D007533:Isoleucine-tRNA Ligase