On the Mechanism and Origin of Isoleucyl-tRNA Synthetase Editing against Norvaline. Issue 6 (15th March 2019)

• Record Type: Journal Article
• Authors: Bilus, Mirna; Semanjski, Maja; Mocibob, Marko; Zivkovic, Igor; Cvetesic, Nevena; Tawfik, Dan S.; Toth-Petroczy, Agnes; Macek, Boris; Gruic-Sovulj, Ita
• Is Part Of: Journal of molecular biology. Volume 431:Issue 6(2019)
• Page Start: 1284
• Page End: 1297
• Publication Date: 2019-03-15
• Subjects: aa-AMP aminoacyl-adenylate -- aaRS aminoacyl-tRNA synthetase -- aa-tRNA aminoacylated tRNA -- CFU colony-forming units -- I/L/VRS isoleucyl, leucyl, valyl-tRNA synthtetase -- IleRS isoleucyl-tRNA synthetase -- LC–MS/MS liquid chromatography–tandem mass spectrometry -- LeuRS leucyl-tRNA synthetase -- MS mass spectrometry -- MS/MS tandem mass spectrometry -- Nva norvaline -- ValRS valyl-tRNA synthetase -- WT wild-type; aminoacyl-tRNA synthetase -- mistranslation -- proofreading -- non-proteinogenic amino acids -- primordial translation; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2019.01.029
• Languages: English
• ISSNs: 0022-2836

Abstract

Abstract: Aminoacyl-tRNA synthetases (aaRSs), the enzymes responsible for coupling tRNAs to their cognate amino acids, minimize translational errors by intrinsic hydrolytic editing. Here, we compared norvaline (Nva), a linear amino acid not coded for protein synthesis, to the proteinogenic, branched valine (Val) in their propensity to mistranslate isoleucine (Ile) in proteins. We show that in the synthetic site of isoleucyl-tRNA synthetase (IleRS), Nva and Val are activated and transferred to tRNA at similar rates. The efficiency of the synthetic site in pre-transfer editing of Nva and Val also appears to be similar. Post-transfer editing was, however, more rapid with Nva and consequently IleRS misaminoacylates Nva-tRNA Ile at slower rate than Val-tRNA Ile . Accordingly, an Escherichia coli strain lacking IleRS post-transfer editing misincorporated Nva and Val in the proteome to a similar extent and at the same Ile positions. However, Nva mistranslation inflicted higher toxicity than Val, in agreement with IleRS editing being optimized for hydrolysis of Nva-tRNA Ile . Furthermore, we found that the evolutionary-related IleRS, leucyl- and valyl-tRNA synthetases (I/L/VRSs), all efficiently hydrolyze Nva-tRNAs even when editing of Nva seems redundant. We thus hypothesize that editing of Nva-tRNAs had already existed in the last common ancestor of I/L/VRSs, and that the editing domain of I/L/VRSs had primarily evolved to prevent infiltration of Nva into modern proteins. Graphical Abstract: Unlabelled Image Highlights: Induced mistranslation of non-proteinogenic norvaline and valine was compared. Norvaline and valine misincorporate at overlapping isoleucine positions. The same frequency of norvaline mistranslation inflicts higher toxicity. Norvaline is a preferred target of IleRS editing. Norvaline could have participated in primitive translation.