Modomics - A Database of RNA Modifications

ID Card:

Full name: tRNA cytidine(34) acetyltransferase
Synonym: YpfI, JW2459
GI: 2495648
Orf: b2474
COG: COG1444
UniProt: P76562
Structures: | 2ZPA |
Enzyme type: acetyltransferase
Position of modification - modification: t:34 - ac4C

PDB Structures:


Structure Description:


Abstract of the PDB Structure's related Publication:

Post-transcriptional RNA modifications in the anticodon of transfer RNAs frequently contribute to the high fidelity of protein synthesis. In eubacteria, two genome-encoded transfer RNA (tRNA) species bear the same CAU sequence as the anticodons, which are differentiated by modified cytidines at the wobble positions. The elongator tRNA(Met) accepts an acetyl moiety at the wobble base to form N(4)-acetylcytidine (ac(4)C): an inherent modification ensures precise decoding of the AUG codon by strengthening C-G base-pair interaction and concurrently preventing misreading of the near cognate AUA codon. We have determined the crystal structure of tRNA(Met) cytidine acetyltransferase (TmcA) from Escherichia coli complexed with two natural ligands, acetyl-CoA and ADP, at 2.35 A resolution. The structure unexpectedly reveals an idiosyncratic RNA helicase module fused with a GCN5-related N-acetyltransferase (GNAT) fold, which intimately cross-interact. Taken together with the biochemical evidence, we further unravelled the function of acetyl-CoA as an enzyme-activating switch, and propose that an RNA helicase motor driven by ATP hydrolysis is used to deliver the wobble base to the active centre of the GNAT domain.

Download RCSB-PDB Structures:

Pdb Files   2ZPA.pdb  
Pdbx/mmCIF Files   2ZPA.cif  

Protein sequence:



tRNAMet cytidine acetyltransferase. The substrate of this reaction is elongator tRNAMet. Apart from acetyltransferase it posses also a helicase domain.

Reaction Substrate SubstrateType Position (Anti)Codon Modified (Anti)Codon Amino Acid Change Transcript Name Transcript Region Cellular Localization References
C:ac4C tRNA (t)   34


Title Authors Journal Details PubMed Id DOI
The RNA acetyltransferase driven by ATP hydrolysis synthesizes N4-acetylcytidine of tRNA anticodon. Ikeuchi Y, Kitahara K, Suzuki T EMBO J [details] 18668122 -
RNA helicase module in an acetyltransferase that modifies a specific tRNA anticodon. Chimnaronk S, Suzuki T, Manita T, Ikeuchi Y, Yao M, Suzuki T, Tanaka I EMBO J [details] 19322199 -