Agmatine-conjugated cytidine in a tRNA anticodon is essential for AUA decoding in archaea

Nat Chem Biol. 2010 Apr;6(4):277-82. doi: 10.1038/nchembio.323. Epub 2010 Feb 7.


A modified base at the first (wobble) position of some tRNA anticodons is critical for deciphering the genetic code. In eukaryotes and eubacteria, AUA codons are decoded by tRNAsIle with modified bases pseudouridine (and/or inosine) and lysidine, respectively. The mechanism by which archaeal species translate AUA codons is unclear. We describe a polyamine-conjugated modified base, 2-agmatinylcytidine (agm(2)C or agmatidine), at the wobble position of archaeal tRNA(Ile) that decodes AUA codons specifically. We demonstrate that archaeal cells use agmatine to synthesize agm(2)C of tRNA(Ile). We also identified a new enzyme, tRNA(Ile)-agm(2)C synthetase (TiaS), that catalyzes agm(2)C formation in the presence of agmatine and ATP. Although agm(2)C is chemically similar to lysidine, TiaS constitutes a distinct class of enzyme from tRNA(Ile)-lysidine synthetase (TilS), suggesting that the decoding systems evolved convergently across domains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agmatine / chemistry*
  • Agmatine / metabolism
  • Anticodon / chemistry*
  • Anticodon / genetics*
  • Anticodon / metabolism
  • Archaea / cytology
  • Archaea / genetics*
  • Archaea / metabolism*
  • Catalysis
  • Cytidine / chemistry*
  • Cytidine / metabolism
  • Ligases / metabolism
  • RNA, Transfer / chemistry*
  • RNA, Transfer / genetics*
  • RNA, Transfer / metabolism


  • Anticodon
  • Cytidine
  • Agmatine
  • RNA, Transfer
  • Ligases

Associated data

  • PubChem-Substance/87326004
  • PubChem-Substance/87326005
  • PubChem-Substance/87326006
  • PubChem-Substance/87326007
  • PubChem-Substance/87326008