Poster abstracts

Poster number 64 submitted by Xiao Ma

Selectivity mechanisms of an aminoacyl-tRNA trans-editing factor

Xiao Ma (Department of Chemistry and Biochemistry, the Ohio State University), Marina Bakhtina (Department of Chemistry and Biochemistry, the Ohio State University), Karin Musier-Forsyth (Department of Chemistry and Biochemistry, the Ohio State University), Mark P. Foster (Department of Chemistry and Biochemistry, the Ohio State University)

Abstract:
Aminoacyl-tRNA synthetases (aaRSs) are responsible for charging their cognate tRNAs with the correct or cognate amino acid. The structural features of aaRS catalytic domains provide a high degree of selectivity for both the amino acid and tRNA; however, given the similar stereochemical properties of many amino acids, errors in tRNA charging can occur, especially for the smaller and isometric amino acids. Organisms in all three domains of life possess editing enzymes that function in trans to deacylate mischarged tRNAs. Caulobacter crescentus ProXp-ala recognizes the terminal base pair, C1:G72, on the acceptor stem of tRNAPro to deacylate mischarged Ala-tRNAPro but not Ala-tRNAAla. We used NMR spectroscopy, binding and activity assays to examine the structural details of this discrimination. We also found that the A76 of tRNAPro was essential for its binding to ProXp-ala, thus supporting a previously proposed interaction with a highly conserved Lys. Ongoing work continues to refine a 3D model of the enzyme-product complex of ProXp-ala bound to a tRNAPro acceptor stem. These studies will improve our understanding of substrate recognition by a bacterial trans-editing factor with the potential to inform new antibiotic drug design.

References:
Das M., Vargas-Rodriguez O., Goto Y., Novoa, E., Pouplana L., Suga H., Musier-Forsyth K., (2014). Distinct tRNA recognition strategies used by a homologous family of editing domains prevent mistranslation. Nucl. Acids Res. 42 (6):3943-3953.

2. Ling J, Reynolds N, Ibba M (2009) Aminoacyl-tRNA synthesis and translational quality control. Annu Rev Microbiol 63:61–78.

3. Danhart, E. M., Bakhtina, M., Cantara, W. A., Kuzmishin, A. B., Ma, X., Sanford, B. L., Košutić, M., Goto, Y., Suga, H., Nakanishi, K., et al. (2017) Conformational and chemical selection by a trans - acting editing domain. Proc. Natl. Acad. Sci. 114, 6774–6783.

Keywords: NMR, Protein-RNA