Document Type
Article
Publication Date
5-16-2016
Abstract
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.
Recommended Citation
Moghal, A., Hwang, L., Faull, K. and Ibba, M. (2016) Multiple quality control pathways limit non-protein amino acid use by yeast cytoplasmic phenylalanyl-tRNA synthetase. J. Biol. Chem. 291, 15796-15805. https://doi.org/10.1074/jbc.M116.726828
Copyright
American Society for Biochemistry and Molecular Biology
Included in
Amino Acids, Peptides, and Proteins Commons, Biochemistry Commons, Cellular and Molecular Physiology Commons, Molecular Biology Commons, Nucleic Acids, Nucleotides, and Nucleosides Commons, Other Biochemistry, Biophysics, and Structural Biology Commons
Comments
This article was originally published in Journal of Biological Chemistry, volume 291, in 2016. https://doi.org/10.1074/jbc.M116.726828