Homologous trans-editing factors with broad tRNA specificity prevent mistranslation caused by serine/threonine misactivation.
Aminoacyl-tRNA synthetases (ARSs) establish the rules of the genetic code, whereby each amino acid is attached to a cognate tRNA. Errors in this process lead to mistranslation, which can be toxic to cells. The selective forces exerted by species-specific requirements and environmental conditions potentially shape quality-control mechanisms that serve to prevent mistranslation. A family of editing factors that are homologous to the editing domain of bacterial prolyl-tRNA synthetase includes the previously characterized trans-editing factors ProXp-ala and YbaK, which clear Ala-tRNA(Pro) and Cys-tRNA(Pro), respectively, and three additional homologs of unknown function, ProXp-x, ProXp-y, and ProXp-z. We performed an in vivo screen of 230 conditions in which an Escherichia coli proXp-y deletion strain was grown in the presence of elevated levels of amino acids and specific ARSs. This screen, together with the results of in vitro deacylation assays, revealed Ser- and Thr-tRNA deacylase function for this homolog. A similar activity was demonstrated for Bordetella parapertussis ProXp-z in vitro. These proteins, now renamed "ProXp-ST1" and "ProXp-ST2," respectively, recognize multiple tRNAs as substrates. Taken together, our data suggest that these free-standing editing domains have the ability to prevent mistranslation errors caused by a number of ARSs, including lysyl-tRNA synthetase, threonyl-tRNA synthetase, seryl-tRNA synthetase, and alanyl-tRNA synthetase. The expression of these multifunctional enzymes is likely to provide a selective growth advantage to organisms subjected to environmental stresses and other conditions that alter the amino acid pool.
Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210;
Ziwei
Z
Liu
Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210;
Oscar
O
Vargas-Rodriguez
Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan;
Yuki
Y
Goto
Institute for Research in Biomedicine, 08028 Barcelona, Catalonia, Spain; and.
Eva Maria
EM
Novoa
Institute for Research in Biomedicine, 08028 Barcelona, Catalonia, Spain; and Catalan Institution for Research and Advanced Studies, 08010 Barcelona, Catalonia, Spain.
Lluís
L
Ribas de Pouplana
Department of Chemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan;
Hiroaki
H
Suga
Department of Chemistry and Biochemistry and Center for RNA Biology, The Ohio State University, Columbus, OH 43210; musier@chemistry.ohio-state.edu.
Karin
K
Musier-Forsyth
D000596:Amino Acids / Q000737:chemistry; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry*; D001407:Bacillus / Q000378:metabolism; D002384:Catalysis; D049109:Cell Proliferation; D019295:Computational Biology; D004926:Escherichia coli / Q000378:metabolism; D006868:Hydrolysis; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D017393:RNA Editing; D012343:RNA, Transfer / Q000737:chemistry*; D015203:Reproducibility of Results; D012694:Serine / Q000737:chemistry*; D013379:Substrate Specificity; D013696:Temperature; D013912:Threonine / Q000737:chemistry*
D000596:Amino Acids; D013912:Threonine; D012694:Serine; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases
ProXp; aminoacyl tRNA synthetase; protein synthesis; quality control; trans-editing