Identification of the enzyme responsible for N1-methylation of pseudouridine 54 in archaeal tRNAs

RNA. 2012 Mar;18(3):412-20. doi: 10.1261/rna.028498.111. Epub 2012 Jan 24.


tRNAs from all three kingdoms of life contain a variety of modified nucleotides required for their stability, proper folding, and accurate decoding. One prominent example is the eponymous ribothymidine (rT) modification at position 54 in the T-arm of eukaryotic and bacterial tRNAs. In contrast, in most archaea this position is occupied by another hypermodified nucleotide: the isosteric N1-methylated pseudouridine. While the enzyme catalyzing pseudouridine formation at this position is known, the pseudouridine N1-specific methyltransferase responsible for this modification has not yet been experimentally identified. Here, we present biochemical and genetic evidence that the two homologous proteins, Mja_1640 (COG 1901, Pfam DUF358) and Hvo_1989 (Pfam DUF358) from Methanocaldococcus jannaschii and Haloferax volcanii, respectively, are representatives of the methyltransferase responsible for this modification. However, the in-frame deletion of the pseudouridine N1-methyltransferase gene in H. volcanii did not result in a discernable phenotype in line with similar observations for knockouts of other T-arm methylating enzymes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Archaea / enzymology*
  • Archaea / genetics*
  • Base Pairing
  • Base Sequence
  • DNA-Directed RNA Polymerases / chemistry
  • DNA-Directed RNA Polymerases / metabolism
  • Gene Knockout Techniques
  • Haloferax volcanii / genetics
  • Haloferax volcanii / metabolism
  • Methanococcales / genetics
  • Methanococcales / metabolism
  • Methylation
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Phylogeny
  • Protein Conformation
  • Pseudouridine / metabolism*
  • RNA, Transfer / chemistry
  • RNA, Transfer / metabolism*
  • Sequence Alignment
  • tRNA Methyltransferases / genetics
  • tRNA Methyltransferases / metabolism*


  • Pseudouridine
  • RNA, Transfer
  • tRNA Methyltransferases
  • nucleus-encoded phage-type RNA polymerase
  • DNA-Directed RNA Polymerases