Agmatine-conjugated cytidine in a tRNA anticodon is essential for AUA decoding in archaea.
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.
Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, Japan.
Yoshiho
Y
Ikeuchi
Satoshi
S
Kimura
Tomoyuki
T
Numata
Daigo
D
Nakamura
Takashi
T
Yokogawa
Toshihiko
T
Ogata
Takeshi
T
Wada
Takeo
T
Suzuki
Tsutomu
T
Suzuki
D000376:Agmatine / Q000737:chemistry* / Q000378:metabolism; D000926:Anticodon / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001105:Archaea / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D002384:Catalysis; D003562:Cytidine / Q000737:chemistry* / Q000378:metabolism; D008025:Ligases / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
D000926:Anticodon; D003562:Cytidine; D000376:Agmatine; D012343:RNA, Transfer; D008025:Ligases