Characterization of two homologous 2'-O-methyltransferases showing different specificities for their tRNA substrates

RNA. 2014 Aug;20(8):1257-71. doi: 10.1261/rna.044503.114. Epub 2014 Jun 20.


The 2'-O-methylation of the nucleoside at position 32 of tRNA is found in organisms belonging to the three domains of life. Unrelated enzymes catalyzing this modification in Bacteria (TrmJ) and Eukarya (Trm7) have already been identified, but until now, no information is available for the archaeal enzyme. In this work we have identified the methyltransferase of the archaeon Sulfolobus acidocaldarius responsible for the 2'-O-methylation at position 32. This enzyme is a homolog of the bacterial TrmJ. Remarkably, both enzymes have different specificities for the nature of the nucleoside at position 32. While the four canonical nucleosides are substrates of the Escherichia coli enzyme, the archaeal TrmJ can only methylate the ribose of a cytidine. Moreover, the two enzymes recognize their tRNA substrates in a different way. We have solved the crystal structure of the catalytic domain of both enzymes to gain better understanding of these differences at a molecular level.

Keywords: SPOUT; methyltransferase; modified nucleosides; tRNA.

MeSH terms

  • Archaea / genetics
  • Archaea / metabolism
  • Bacterial Proteins / metabolism
  • Catalysis
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Inverted Repeat Sequences
  • Models, Molecular
  • Mutation
  • Nucleic Acid Conformation
  • Nucleosides / chemistry
  • Protein Binding
  • Protein Conformation
  • Protein Interaction Domains and Motifs
  • Protein Multimerization
  • RNA, Transfer / chemistry
  • RNA, Transfer / genetics
  • RNA, Transfer / metabolism*
  • Reproducibility of Results
  • Substrate Specificity
  • tRNA Methyltransferases / chemistry
  • tRNA Methyltransferases / metabolism*


  • Bacterial Proteins
  • Nucleosides
  • RNA, Transfer
  • tRNA Methyltransferases