Poster abstracts
Poster number 21 submitted by Alexandra Kuzmishin Nagy
Quality control by trans-editing factor ProXp-x prevents global mistranslation of non-protein amino acids
Lexie Kuzmishin Nagy (Department of Chemistry and Biochemistry; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA), Wiliam Cantara (Department of Chemistry and Biochemistry; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA), Yuki Goto (Department of Chemistry, Graduate School of Science, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan), Hiro 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; Center for RNA Biology, The Ohio State University, Columbus, OH 43210, USA)
Abstract:
Aminoacyl-tRNA (aa-tRNA) formation catalyzed by aminoacyl-tRNA synthetases (aaRSs) is a critical checkpoint of protein synthesis. Due to similarities in amino acid structure, aaRSs can mischarge non-cognate amino acids onto tRNAs in vivo. The insertion (INS) domain present in some bacterial prolyl-tRNA synthetases (ProRS) edits Ala-tRNAPro species mischarged by bacterial ProRS. Additionally, single-domain trans-editing factors structurally homologous to INS are present in many bacteria, presumably to clear other mischarged aa-tRNAs. Rhodopseudomonas palustris ProXp-x is a trans-editing domain that clears the known ProRS aminoacylation error Ala-tRNAPro, but also edits tRNAPro, tRNAVal, tRNAIle, and tRNALeu mischarged with the non-protein amino acid 2-aminobutyrate (Abu) in vitro. Here, we show ProXp-x also robustly edits D-Ala-tRNAPro and D-Thr-tRNAVal in vitro. D-Ala-tRNAPro is also cleared by most INS-like trans-editing proteins we tested in vitro, including those encoded in eukaryotes. In bacteria, Abu is an intermediate of Thr biosynthesis and D-amino acids are synthesized from their L-isomers or are acquired from the environment and neighboring organisms. Our results indicate that editing by ProXp-x may offer advantages to cells, especially under environmental conditions where concentrations of non-protein amino acids may challenge the substrate specificity of aaRSs. Cell-based experiments are underway to explore phenotypic differences between wild-type and ProXp-x null R. palustris strains under a variety of growth conditions and cellular stresses. Taken together, this work has important implications for understanding the threats non-protein amino acids pose to protein synthesis and how bacteria prevent these errors.
Keywords: aminoacyl-tRNA, aaRS, non-protein amino acid