tRNA uridine(34) acetyltransferase, which mediates formation of carboxymethyluridine in the wobble base at position 34 in tRNAs (PubMed:25151136, PubMed:30733442). The proposed mechanism is the following: (i) recruits S-adenosyl-L-methionine and cleaves it to generate a 5'-deoxyadenosine radical (5'-dA) in the radical S-adenosyl-L-methionine (rSAM) region, (ii) hydrolyzes acetyl-CoA in the N-acetyltransferase domain and (iii) an acetyl radical is formed by the products of the two domains and (iv) is transferred onto the C5 position of uridine(34) in the bound tRNA molecule (PubMed:25151136). Does not show protein lysine acetyltransferase activity (PubMed:30733442). acetyl-CoA + H2O + S-adenosyl-L-methionine + uridine(34) in tRNA = 5'-deoxyadenosine + carboxymethyluridine(34) in tRNA + CoA + 2 H(+) + L-methionine Binds 1 [4Fe-4S] cluster. The cluster is coordinated with 3 cysteines and an exchangeable S-adenosyl-L-methionine. tRNA modification. Belongs to the ELP3 family.