Poster abstracts
Poster number 19 submitted by Arundhati Kavoor
Oxidative Stress Regulates E. coli Alanyl-tRNA Synthetase Activity
Arundhati Kavoor (MCDB), Dr. Paul Kelly (MCDB)
Abstract:
Accuracy during translation ensures faithful conversion of the genetic code. Aminoacyl tRNA-synthetases (aaRS) are essential enzymes that attach an amino acid to a cognate tRNA. The aaRS first activates an amino acid in an ATP-dependent manner to form an aminoacyl adenylate. Next, the aaRS attaches the aminoacyl adenylate to the terminal adenosine residue of the cognate tRNA. The aminoacylated tRNA is transported to the ribosome by the elongation factor Tu and participates in translation. AaRSs play a major role in maintaining translational accuracy by attaching the correct amino acids to their cognate tRNAs. Although the active site pockets of many aaRSs are able to discriminate against the wrong amino acid, the shared chemicophysical structure of some amino acids can lead to mis-activated amino acids. To prevent mistranslation, some aaRS have an additional editing domain capable of hydrolyzing mis-activated amino acids. Recent observations have shown that during oxidative stress, reactive oxygen species (ROS) can oxidize aaRSs resulting in either a positive or negative effect on aminoacylation fidelity. As defects in alanyl-tRNA synthetase (AlaRS) fidelity have been shown to cause defects from bacteria to mice, we wanted to determine the effect of oxidation on AlaRS activity. Here, we show that oxidation of AlaRS does not affect cognate activation of alanine or the editing activity against its non-cognate substrates, serine and glycine. However, oxidative stress increased the rate of tRNAAla aminoacylation threefold, accompanied by the oxidation of four residues in AlaRS. Current work is focused on better understanding the regulation of AlaRS and other aaRSs that are critical in maintaining translational accuracy.
References:
1. Ibba M, Söll D (2000) Aminoacyl-tRNA synthesis. Annu Rev Biochem. 69:617–650.
2. Ling J, Reynolds N, Ibba M (2009) Aminoacyl-tRNA synthesis and translational quality control. Annu Rev Microbiol. 63:61–78.
3. Ling J, Söll D (2010) Severe oxidative stress induces protein mistranslation through impairment of an aminoacyl-tRNA synthetase editing site. Proc Natl Acad Sci USA. 107:4028–4033.
4. Steiner, R. E., Kyle, A. M., Ibba, M. (2019). Oxidation of phenylalanyl-tRNA synthetase positively regulates translational quality control. Proceedings of the National Academy of Sciences. 116(20), 10058-10063.
5. Kelly P, et al. (2019) Alanyl-tRNA synthetase quality control prevents global dysregulation of the Escherichia coli proteome. mBio. 10:e02921-19.
Keywords: tRNA, Aminoacyl-tRNA synthetase