Glycosylation of queuosine in tRNAs contributes to optimal translation and post-embryonic growth in vertebrates

ABSTRACT: Post-transcriptional modification of tRNAs is critical for protein synthesis. Queuosine (Q), a 7-deaza-guanosine derivative, is present at the first position of anticodons of several tRNA species. In vertebrate tRNAs for Tyr and Asp, Q is further glycosylated with galactose and mannose to generate galactosyl-queuosine (galQ) and mannosyl-queuosine (manQ), respectively. However, the biogenesis and physiological relevance of Q-glycosylation remain poorly understood. Here, we biochemically identified two RNA glycosylases, queuosine-tRNA galactosyltransferase (QTGAL) and queuosine-tRNA mannosyltransferase (QTMAN), and successfully reconstituted galQ and manQ formation on the respective tRNAs in the presence of nucleotide diphosphate sugars. Ribosome profiling analyses of human knockout (KO) cells of QTGAL and QTMAN revealed that Q-glycosylation slowed down elongation at the cognate codons, UAC and GAC (GAU), respectively. Furthermore, protein aggregates were significantly increased in both KO cell lines, indicating that Q-glycosylation contributes to proteostasis of nascent proteins. We determined atomic structures of human cytoplasmic tRNAs for Try and Asp bound to the ribosome A-site, providing the molecular basis of codon recognition regulated by galQ and manQ. Furthermore, zebrafish qtgal and qtman KO lines displayed shortened body length, suggesting Q-glycosylation is required for post-embryonic growth in vertebrates. These findings demonstrate that Q-glycosylation modulates codon-specific translation to optimize the decoding speed in protein synthesis, thereby maintaining correct folding of nascent proteins, proteome integrity, and normal growth of vertebrates.

ORGANISM(S): Homo sapiens

PROVIDER: GSE213181 | GEO | 2023/11/21

REPOSITORIES: GEO