Translational adaptation to heat stress is mediated by RNA 5-methylcytosine in Caenorhabditis elegans

EMBO J. 2021 Mar 15;40(6):e105496. doi: 10.15252/embj.2020105496. Epub 2020 Dec 7.


Methylation of carbon-5 of cytosines (m5 C) is a post-transcriptional nucleotide modification of RNA found in all kingdoms of life. While individual m5 C-methyltransferases have been studied, the impact of the global cytosine-5 methylome on development, homeostasis and stress remains unknown. Here, using Caenorhabditis elegans, we generated the first organism devoid of m5 C in RNA, demonstrating that this modification is non-essential. Using this genetic tool, we determine the localisation and enzymatic specificity of m5 C sites in the RNome in vivo. We find that NSUN-4 acts as a dual rRNA and tRNA methyltransferase in C. elegans mitochondria. In agreement with leucine and proline being the most frequently methylated tRNA isoacceptors, loss of m5 C impacts the decoding of some triplets of these two amino acids, leading to reduced translation efficiency. Upon heat stress, m5 C loss leads to ribosome stalling at UUG triplets, the only codon translated by an m5 C34-modified tRNA. This leads to reduced translation efficiency of UUG-rich transcripts and impaired fertility, suggesting a role of m5 C tRNA wobble methylation in the adaptation to higher temperatures.

Keywords: Caenorhabditis elegans; 5-methylcytosine; NSUN; RNA modifications; translation efficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-Methylcytosine / metabolism*
  • Adaptation, Physiological / genetics*
  • Animals
  • CRISPR-Cas Systems / genetics
  • Caenorhabditis elegans / genetics*
  • Caenorhabditis elegans / physiology
  • Cytosine / chemistry
  • Gene Editing
  • Heat-Shock Response / genetics*
  • Hot Temperature
  • Leucine / chemistry
  • Methyltransferases / metabolism
  • Mitochondria / genetics
  • Mitochondria / metabolism
  • Proline / chemistry
  • Protein Biosynthesis / genetics
  • Protein Biosynthesis / physiology
  • RNA / chemistry
  • RNA / genetics
  • RNA Processing, Post-Transcriptional / genetics*
  • Ribosomes / metabolism


  • RNA
  • 5-Methylcytosine
  • Cytosine
  • Proline
  • Methyltransferases
  • Leucine

Associated data

  • GEO/GSE144822
  • GEO/GSE146256