Poster abstracts
Poster number 2 submitted by Jawad Abid
Human trans-editing enzyme displays tRNA acceptor stem specificity and relaxed amino acid selectivity
Oscar Vargas-Rodriguez (Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.), Marina Bakhtina (Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.), Daniel McGowan (Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.), Jawad Abid (Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.), Hiroaki Suga (Department of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan.), Karin Musier-Forsyth (Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA.)
Abstract:
Aminoacyl-tRNA synthetases (ARSs) are a group of ancient enzymes responsible for pairing amino acids (aa) with their cognate tRNAs. Due to similarity in sizes and chemical properties of aa, ARSs are prone to errors in aminoacylation. Prolyl-tRNA synthetase (ProRS) mischarges Ala on to tRNAPro, which can be detrimental to translation fidelity and cell viability. These errors can be corrected by an editing domain present in some ProRS or by free standing trans-editing proteins. We previously showed that the Caulobacter crescentus (Cc) ProXp-ala uses a size-based exclusion mechanism and conformational selection to specifically recognize Ala-tRNAPro. In the bacterial system, tRNA acceptor stem bases G72 and A73 act as recognition elements for ProXp-ala. However, the mechanism by which Homo sapiens (Hs) ProXp-ala recognizes aa-tRNA remained to be explored. Here, we report that Hs ProXp-ala is also an efficient Ala-tRNAPro deacylase and has strong recognition elements in the Hs tRNAPro acceptor stem including bases C72 and C73. Mutating conserved residues in the substrate binding pocket of Hs and Cc ProXp-ala modulates the aa selectivity of these enzymes. Our results reveal the evolutionary divergence between bacterial and Hs ProXp-ala in their tRNA and aa selectivity and sheds light on how these proteins coevolved with their tRNA substrates. Taken together, these results illustrate how the mechanism of substrate selection diverged during the evolution of the ProXp-ala family and provide the first example of a trans-editing domain whose specificity evolved to adapt to the changes in its tRNA substrate.
References:
Vargas-Rodriguez, O., Bakhtina, M., McGowan, D., Abid, J., Goto, Y., Suga, H., & Musier-Forsyth, K. (2020). Human trans-editing enzyme displays tRNA acceptor-stem specificity and relaxed amino acid selectivity. Journal of Biological Chemistry, 295(48), 16180-16190.
Keywords: Aminoacyl-tRNA synthetases, tRNA editing