Catalytic tRNA acetyltransferase subunit of the elongator complex which is required for multiple tRNA modifications, including mcm5U (5-methoxycarbonylmethyl uridine), mcm5s2U (5-methoxycarbonylmethyl-2-thiouridine), and ncm5U (5-carbamoylmethyl uridine) (By similarity). In the elongator complex, acts as a tRNA uridine(34) acetyltransferase by mediating formation of carboxymethyluridine in the wobble base at position 34 in tRNAs (By similarity). Stabilizes transcriptional repressor snai1 by inhibiting its ubiquitination which promotes neural crest cell migration (By similarity). 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; 5-methoxycarbonylmethyl-2-thiouridine-tRNA biosynthesis. Component of the elongator complex (By similarity). Interacts with transcriptional repressors snai1 and snai2; interaction with snai1 inhibits its ubiquitination and stabilizes it (By similarity). Belongs to the ELP3 family. The elongator complex was originally thought to play a role in transcription elongation. However, it is no longer thought to play a direct role in this process and its primary function is thought to be in tRNA modification.