Naturally occurring dual recognition of tRNAHis substrates with and without a universal identity element. Issue 9 (2nd September 2019)

• Record Type: Journal Article
• Authors: Lee, Yi-Hsueh; Lo, Ya-Ting; Chang, Chia-Pei; Yeh, Chung-Shu; Chang, Tien-Hsien; Chen, Yu-Wei; Tseng, Yi-Kuan; Wang, Chien-Chia
• Is Part Of: RNA biology. Volume 16:Issue 9(2019)
• Page Start: 1275
• Page End: 1285
• Publication Date: 2019-09-02
• Subjects: Aminoacyl -- tRNA synthetase -- Caenorhabditis elegans -- identity element -- protein synthesis -- tRNA -- translation; RNA -- Periodicals; Molecular biology -- Periodicals; Molecular biology; RNA; Periodicals; 572.8805
• DOI: 10.1080/15476286.2019.1626663
• Languages: English
• ISSNs: 1547-6286

Abstract

ABSTRACT: The extra 5ʹ guanine nucleotide (G-1) on tRNA His is a nearly universal feature that specifies tRNA His identity. The G-1 residue is either genome encoded or post-transcriptionally added by tRNA His guanylyltransferase (Thg1). Despite Caenorhabditis elegans being a Thg1-independent organism, its cytoplasmic tRNA His (CetRNAn His ) retains a genome-encoded G-1. Our study showed that this eukaryote possesses a histidyl-tRNA synthetase (CeHisRS) gene encoding two distinct HisRS isoforms that differ only at their N-termini. Most interestingly, its mitochondrial tRNA His (CetRNAm His ) lacks G-1, a scenario never observed in any organelle. This tRNA, while lacking the canonical identity element, can still be efficiently aminoacylated in vivo. Even so, addition of G-1 to CetRNAm His strongly enhanced its aminoacylation efficiency in vitro. Overexpression of CeHisRS successfully bypassed the requirement for yeast THG1 in the presence of CetRNAn His without G-1. Mutagenesis assays showed that the anticodon takes a primary role in CetRNA His identity recognition, being comparable to the universal identity element. Consequently, simultaneous introduction of both G-1 and the anticodon of tRNA His effectively converted a non-cognate tRNA to a tRNA His -like substrate. Our study suggests that a new balance between identity elements of tRNA His relieves HisRS from the absolute requirement for G-1.