Poster abstracts
Poster number 34 submitted by Rebecca Mann
Regulation of translational quality control in Salmonella Typhimurium
Rebecca Mann (Ohio State Biochemistry Program ), Michael Ibba (Department of Microbiology)
Abstract:
Translational quality control ensures accurate protein synthesis which is an essential cellular process. Aminoacyl tRNA synthetases are critical enzymes that function during translation to attach a corresponding tRNA to the appropriate amino acid. Some of these enzymes, including phenylalanine tRNA synthetase (PheRS), have editing mechanisms to prevent misaminoacylation of non-cognate amino acids to tRNA(1). Oxidative stress has been shown to diminish translational quality control by oxidizing a critical cysteine in the editing domain of threonyl-tRNA synthetase, thus inhibiting the hydrolysis of Ser-tRNAThr(2). Treating cells with hydrogen peroxide has been shown to alter the amino acid pools by oxidizing phenylalanine into tyrosine and its isomers, increasing the pool of non-cognate substrates and therefore increasing the possibility of misacylation of tRNA(3). Due to the increased non-cognate substrate availability, PheRS must maintain accuracy during periods of oxidative stress; however, how PheRS changes structurally and enzymatically during oxidative stress has yet to be elucidated. Upon treatment of PheRS with hydrogen peroxide, structural analysis revealed differential oxidation patterns between protein subunits, paired with a change in the overall secondary structure. Interestingly, this treatment did not impact the cognate amino acid aminoacylation activity, but did lead to increased proofreading activity. These results suggest a possible evolutionary relationship between the effect of oxidative stress on the amino acid pool and the enzyme. Further examination of the structural changes of PheRS will provide new insight into the mechanism of PheRS proofreading and its independence from the active site domain.
References:
1. Ling J, Reynolds N, Ibba M. Aminoacyl-tRNA synthesis and translational quality control. Annu Rev Microbiol. 2009;63:61-78. doi: 10.1146/annurev.micro.091208.073210. PubMed PMID: 19379069.
2. Ling J, Soll D. Severe oxidative stress induces protein mistranslation through impairment of an aminoacyl-tRNA synthetase editing site. Proc Natl Acad Sci U S A. 2010;107(9):4028-33. doi: 10.1073/pnas.1000315107. PubMed PMID: 20160114; PMCID: PMC2840151.
3. Bullwinkle TJ, Reynolds NM, Raina M, Moghal A, Matsa E, Rajkovic A, Kayadibi H, Fazlollahi F, Ryan C, Howitz N, Faull KF, Lazazzera BA, Ibba M. Oxidation of cellular amino acid pools leads to cytotoxic mistranslation of the genetic code. Elife. 2014;3. doi: 10.7554/eLife.02501. PubMed PMID: 24891238; PMCID: PMC4066437.
Keywords: tRNA, translation, Salmonella