Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.1.1.10 (methionyl-tRNA synthetase)
 387 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Methionine is the universal amino acid for initiation of protein synthesis in all known organisms. The amino acid is coupled to a specific initiator methionine tRNA by methionyl-tRNA synthetase. In Escherichia coli, attachment of methionine to the initiator tRNA (tRNA(fMet)) has been shown to be dependent on synthetase recognition of the methionine anticodon CAU (complementary to the initiation codon AUG), [Schulman, L. H., & Pelka, H. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 6755-6759]. We show here that alteration of the anticodon of tRNA(fMet) to GAC or GAA leads to aminoacylation of the initiator tRNA with valine or phenylalanine. In addition, tRNA(fMet) carrying these amino acids initiates in vivo protein synthesis when provided with initiation codons complementary to the modified anticodons. These results indicate that the sequence of the anticodon of tRNA(fMet) dictates the identity of the amino acid attached to the initiator tRNA in vivo and that there are no subsequent steps which prevent initiation of E. coli protein synthesis by valine and phenylalanine. The methods described here also provide a convenient in vivo assay for further examination of the role of the anticodon in tRNA amino acid acceptor identity.
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PMID:Initiation of in vivo protein synthesis with non-methionine amino acids. 211 6

In mammalian cells under oxidative stress, the methionyl-tRNA synthetase (MetRS) misacylates noncognate tRNAs at frequencies as high as 10% distributed among up to 28 tRNA species. Instead of being detrimental for the cell, misincorporation of methionine residues in the proteome reduces the risk of oxidative damage to proteins, which aids the oxidative stress response. tRNA microarrays have been essential for the detection of the full pattern of misacylated tRNAs, but have limited capacity to investigate the misacylation and mistranslation mechanisms in live cells. Here we develop a dual-fluorescence reporter to specifically measure methionine misincorporation at glutamic acid codons GAA and GAG via tRNA(Glu) mismethionylation in human cells. Our method relies on mutating a specific Met codon in the active site of the fluorescent protein mCherry to a Glu codon that renders mCherry nonfluorescent when translation follows the genetic code. Mistranslation utilizing mismethionylated tRNA(Glu) restores fluorescence in proportion to the amount of misacylated tRNA(Glu). This cellular approach works well for both transient transfection and established stable HEK293 lines. It is rapid, straightforward, and well suited for high-throughput activity analysis under a wide range of physiological conditions. As a proof of concept, we apply this method to characterize the effect of human tRNA(Glu) isodecoders on mistranslation and discuss the implications of our findings.
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PMID:A dual fluorescent reporter for the investigation of methionine mistranslation in live cells. 2672 21