One of the six protein cofactors required for the synthesis of 5-carboxymethyl group (cm5) on the wobble uridine-34 of a few tRNA. Acetate or acetyl-CoA is the donor of acetyl group, but the detailed mechanism of the reaction is still unknown. The cm5U derivative is the intermediate for further biochemical transformation of U34 derivative to either 5-methoxycarbonylmethyl uridine (mcm5U) catalysed by Trm9/Trm112 or 5-carbamoylmethyluridine (ncm5U) catalysed by a still unknown enzyme. Mutation in Elp (especially Elp3) influences telomeric gene silencing and DNA damage response. The multi-subunit complex El1-6 also interacts with elongating RNA polymerase II (RNAPII) is thought to facilitate transcription through histone acetylation.