Reduced Amino Acid Specificity of Mammalian Tyrosyl-tRNA Synthetase is Associated with Elevated Mistranslation of Tyr Codons

Authors

Medha Raina, The Ohio State University
Adil Moghal, The Ohio State University
Amanda Kano, Amgen Incorporated
Mathew Jerums, Amgen Incorporated
Paul D. Schnier, Amgen Incorporated
Shun Luo, Amgen Incorporated
Rohini Deshpande, Amgen Incorporated
Pavel D. Bondarenko, Amgen Incorporated
Henry Lin, Amgen Incorporated
Michael Ibba, Chapman UniversityFollow

Document Type

Article

Publication Date

5-14-2014

Abstract

Quality control operates at different steps in translation to limit errors to approximately one mistranslated codon per 10,000 codons during mRNA-directed protein synthesis. Recent studies have suggested that error rates may actually vary considerably during translation under different growth conditions. Here we examined the misincorporation of Phe at Tyr codons during synthesis of a recombinant antibody produced in tyrosine-limited Chinese hamster ovary (CHO) cells. Tyr to Phe replacements were previously found to occur throughout the antibody at a rate of up to 0.7% irrespective of the identity or context of the Tyr codon translated. Despite this comparatively high mistranslation rate, no significant change in cellular viability was observed. Monitoring of Phe and Tyr levels revealed that changes in error rates correlated with changes in amino acid pools, suggesting that mischarging of tRNATyr with noncognate Phe by tyrosyl-tRNA synthetase was responsible for mistranslation. Steady-state kinetic analyses of CHO cytoplasmic tyrosyl-tRNA synthetase revealed a 25-fold lower specificity for Tyr over Phe as compared with previously characterized bacterial enzymes, consistent with the observed increase in translation error rates during tyrosine limitation. Functional comparisons of mammalian and bacterial tyrosyl-tRNA synthetase revealed key differences at residues responsible for amino acid recognition, highlighting differences in evolutionary constraints for translation quality control.

Comments

This article was originally published in Journal of Biological Chemistry, volume 289, in 2014. https://doi.org/10.1074/jbc.M114.564609

Recommended Citation

Raina, M., Moghal, A., Kano, A., Jerums, M., Schnier, P.D., Luo, S., Deshpande, R., Bondarenko, P.V., Lin, H. and Ibba, M. (2014) Reduced amino acid specificity of mammalian tyrosyl-tRNA synthetase is associated with elevated mistranslation of Tyr codons. J. Biol. Chem. 289, 17780-17790. https://doi.org/10.1074/jbc.M114.564609

Copyright

American Society for Biochemistry and Molecular Biology