Dataset Information

Human trans-editing enzyme displays tRNA acceptor-stem specificity and relaxed amino acid selectivity.

ABSTRACT: Accurate translation of genetic information into proteins is vital for cell sustainability. ProXp-ala prevents proteome-wide Pro-to-Ala mutations by hydrolyzing misacylated Ala-tRNA^Pro, which is synthesized by prolyl-tRNA synthetase. Bacterial ProXp-ala was previously shown to combine a size-based exclusion mechanism with conformational and chemical selection for the recognition of the alanyl moiety, whereas tRNA^Pro is selected via recognition of tRNA acceptor-stem elements G72 and A73. The identity of these critical bases changed during evolution with eukaryotic cytosolic tRNA^Pro possessing a cytosine at the corresponding positions. The mechanism by which eukaryotic ProXp-ala adapted to these changes remains unknown. In this work, recognition of the aminoacyl moiety and tRNA acceptor stem by human (Homo sapiens, or Hs) ProXp-ala was examined. Enzymatic assays revealed that Hs ProXp-ala requires C72 and C73 in the context of Hs cytosolic tRNA^Pro for efficient deacylation of mischarged Ala-tRNA^Pro The strong dependence on these bases prevents cross-species deacylation of bacterial Ala-tRNA^Pro or of Hs mitochondrial Ala-tRNA^Pro by the human enzyme. Similar to the bacterial enzyme, Hs ProXp-ala showed strong tRNA acceptor-stem recognition but differed in its amino acid specificity profile relative to bacterial ProXp-ala. Changes at conserved residues in both the Hs and bacterial ProXp-ala substrate-binding pockets modulated this specificity. These results illustrate how the mechanism of substrate selection diverged during the evolution of the ProXp-ala family, providing the first example of a trans-editing domain whose specificity evolved to adapt to changes in its tRNA substrate.

SUBMITTER: Vargas-Rodriguez O

PROVIDER: S-EPMC7705315 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Human trans-editing enzyme displays tRNA acceptor-stem specificity and relaxed amino acid selectivity.

Vargas-Rodriguez Oscar O Bakhtina Marina M McGowan Daniel D Abid Jawad J Goto Yuki Y Suga Hiroaki H Musier-Forsyth Karin K

The Journal of biological chemistry 20201013 48

Accurate translation of genetic information into proteins is vital for cell sustainability. ProXp-ala prevents proteome-wide Pro-to-Ala mutations by hydrolyzing misacylated Ala-tRNAPro, which is synthesized by prolyl-tRNA synthetase. Bacterial ProXp-ala was previously shown to combine a size-based exclusion mechanism with conformational and chemical selection for the recognition of the alanyl moiety, whereas tRNAPro is selected via recognition of tRNA acceptor-stem elements ...[more]

PMID: 33051185

Similar Datasets

Project description:UnlabelledAminoacyl-tRNA synthetases provide the first step in protein synthesis quality control by discriminating cognate from noncognate amino acid and tRNA substrates. While substrate specificity is enhanced in many instances by cis- and trans-editing pathways, it has been revealed that in organisms such as Streptococcus pneumoniae some aminoacyl-tRNA synthetases display significant tRNA mischarging activity. To investigate the extent of tRNA mischarging in this pathogen, the aminoacylation profiles of class I isoleucyl-tRNA synthetase (IleRS) and class II lysyl-tRNA synthetase (LysRS) were determined. Pneumococcal IleRS mischarged tRNA(Ile) with both Val, as demonstrated in other bacteria, and Leu in a tRNA sequence-dependent manner. IleRS substrate specificity was achieved in an editing-independent manner, indicating that tRNA mischarging would only be significant under growth conditions where Ile is depleted. Pneumococcal LysRS was found to misaminoacylate tRNA(Lys) with Ala and to a lesser extent Thr and Ser, with mischarging efficiency modulated by the presence of an unusual U4:G69 wobble pair in the acceptor stems of both pneumococcal tRNA(Lys) isoacceptors. Addition of the trans-editing factor MurM, which also functions in peptidoglycan synthesis, reduced Ala-tRNA(Lys) production by LysRS, providing evidence for cross talk between the protein synthesis and cell wall biogenesis pathways. Mischarging of tRNA(Lys) by AlaRS was also observed, and this would provide additional potential MurM substrates. More broadly, the extensive mischarging activities now described for a number of Streptococcus pneumoniae aminoacyl-tRNA synthetases suggest that adaptive misaminoacylation may contribute significantly to the viability of this pathogen during amino acid starvation.ImportanceStreptococcus pneumoniae is a common causative agent of several debilitating and potentially life-threatening infections, such as pneumonia, meningitis, and infectious endocarditis. Such infections are increasingly difficult to treat due to widespread development of penicillin resistance. High-level penicillin resistance is known to depend in part upon MurM, a protein involved in both aminoacyl-tRNA-dependent synthesis of indirect amino acid cross-linkages within cell wall peptidoglycan and in translation quality control. The involvement of MurM in both protein synthesis and antibiotic resistance identify it as a potential target for the development of new and potent antibiotics for pneumococcal infections. The goals of this work were to identify and characterize S. pneumoniae pathways that can synthesize mischarged tRNAs and to relate these activities to expected changes in protein and peptidoglycan biosynthesis during antibiotic and nutritional stress.

Dataset Information

Human trans-editing enzyme displays tRNA acceptor-stem specificity and relaxed amino acid selectivity.

Publications

Human <i>trans</i>-editing enzyme displays tRNA acceptor-stem specificity and relaxed amino acid selectivity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets