Naturally occurring dual recognition of tRNAHis substrates with and without a universal identity element

Yi Hsueh Lee, Ya Ting Lo, Chia Pei Chang, Chung Shu Yeh, Tien Hsien Chang, Yu Wei Chen, Yi Kuan Tseng, Chien Chia Wang

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The extra 5ʹ guanine nucleotide (G-1) on tRNAHis is a nearly universal feature that specifies tRNAHis identity. The G-1 residue is either genome encoded or post-transcriptionally added by tRNAHis guanylyltransferase (Thg1). Despite Caenorhabditis elegans being a Thg1-independent organism, its cytoplasmic tRNAHis (CetRNAnHis) 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 tRNAHis (CetRNAmHis) 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 CetRNAmHis strongly enhanced its aminoacylation efficiency in vitro. Overexpression of CeHisRS successfully bypassed the requirement for yeast THG1 in the presence of CetRNAnHis without G-1. Mutagenesis assays showed that the anticodon takes a primary role in CetRNAHis identity recognition, being comparable to the universal identity element. Consequently, simultaneous introduction of both G-1 and the anticodon of tRNAHis effectively converted a non-cognate tRNA to a tRNAHis-like substrate. Our study suggests that a new balance between identity elements of tRNAHis relieves HisRS from the absolute requirement for G-1.

Original languageEnglish
Pages (from-to)1275-1285
Number of pages11
JournalRNA Biology
Issue number9
StatePublished - 2 Sep 2019


  • Aminoacyl
  • Caenorhabditis elegans
  • identity element
  • protein synthesis
  • tRNA
  • tRNA synthetase
  • translation


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