tRNA(Met) cytidine acetyltransferase TmcA, N-terminal
This domain of unknown function is often found at the N-terminus of the bacterial tRNA(Met) cytidine acetyltransferase TmcA. TmcA catalyzes the formation of N(4)-acetylcytidine (ac4C) at the wobble position of tRNA(Met) by using acetyl-CoA as an acetyl donor and either ATP or GTP. This modification is thought to ensure precise recognition of the AUG codon by strengthening C-G base-pair interaction and also prevent misrecognition of the near cognate AUA codon. This domain is also found in mammalian N-acetyltransferase 10 (NAT10) and fungal protein Kre33. Kre33 and NAT10 are RNA cytosine acetyltransferases with specificity toward both 18S rRNA and tRNAs and contain additional putative nuclear and nucleolar localization signals (NLS and NoLS respectively).
Jiyao W et al.(2023). "The conserved domain database in 2023.",