Multiple Quality Control Pathways Limit Non-protein Amino Acid Use by Yeast Cytoplasmic Phenylalanyl-tRNA Synthetase

Non-protein amino acids, particularly isomers of the proteinogenic amino acids, present a threat to proteome integrity if they are mistakenly inserted into proteins. Quality control during aminoacyl-tRNA synthesis reduces non-protein amino acid incorporation by both substrate discrimination and proo...

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Bibliographic Details
Published in:The Journal of biological chemistry 2016-07, Vol.291 (30), p.15796-15805
Main Authors: Moghal, Adil, Hwang, Lin, Faull, Kym, Ibba, Michael
Format: Article
Language:English
Subjects:
Acylation
Adenosine Monophosphate - genetics
Adenosine Monophosphate - metabolism
Alanine - genetics
Alanine - metabolism
amino acid
aminoacyl tRNA synthetase
Mutation
Phenylalanine - genetics
Phenylalanine - metabolism
Phenylalanine-tRNA Ligase - genetics
Phenylalanine-tRNA Ligase - metabolism
protein synthesis
Protein Synthesis and Degradation
Quality control
RNA, Fungal - genetics
RNA, Fungal - metabolism
RNA, Transfer, Phe - genetics
RNA, Transfer, Phe - metabolism
Saccharomyces cerevisiae - enzymology
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae Proteins - genetics
Saccharomyces cerevisiae Proteins - metabolism
transfer RNA (tRNA)
translation
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Summary:Non-protein amino acids, particularly isomers of the proteinogenic amino acids, present a threat to proteome integrity if they are mistakenly inserted into proteins. Quality control during aminoacyl-tRNA synthesis reduces non-protein amino acid incorporation by both substrate discrimination and proofreading. For example phenylalanyl-tRNA synthetase (PheRS) proofreads the non-protein hydroxylated phenylalanine derivative m-Tyr after its attachment to tRNAPhe. We now show in Saccharomyces cerevisiae that PheRS misacylation of tRNAPhe with the more abundant Phe oxidation product o-Tyr is limited by kinetic discrimination against o-Tyr-AMP in the transfer step followed by o-Tyr-AMP release from the synthetic active site. This selective rejection of a non-protein aminoacyl-adenylate is in addition to known kinetic discrimination against certain non-cognates in the activation step as well as catalytic hydrolysis of mispaired aminoacyl-tRNAPhe species. We also report an unexpected resistance to cytotoxicity by a S. cerevisiae mutant with ablated post-transfer editing activity when supplemented with o-Tyr, cognate Phe, or Ala, the latter of which is not a substrate for activation by this enzyme. Our phenotypic, metabolomic, and kinetic analyses indicate at least three modes of discrimination against non-protein amino acids by S. cerevisiae PheRS and support a non-canonical role for SccytoPheRS post-transfer editing in response to amino acid stress.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M116.726828