Catalyzes the formation of 3-(3-amino-3-carboxypropyl)uridine (acp3U) at position 47 of tRNAs (PubMed:31804502, PubMed:31863583, PubMed:4597321). Acp3U47 confers thermal stability on tRNA (PubMed:31804502). a uridine in tRNA + S-adenosyl-L-methionine = a 3-[(3S)-3-amino-3-carboxypropyl]uridine in tRNA + H(+) + S-methyl-5'-thioadenosine S-adenosyl-L-methionine + uridine(47) in tRNA(Phe) = 3-[(3S)-3-amino-3-carboxypropyl]uridine(47) in tRNA(Phe) + H(+) + S-methyl-5'-thioadenosine The degree of the acp3U modification at U47 is dependent on the presence of the m7G modification at the preceding nucleotide G46. It also depends on medium conditions. Monomer in solution. Contains 1 DXTW motif (PubMed:31863583). The N-terminal domain binds zinc and is important for activity (PubMed:31863583). Deletion of the gene leads to the loss of the acp3U modification (PubMed:31804502, PubMed:31863583). Mutant has no obvious defect under normal growth conditions (PubMed:31863583). It shows motility defect and genome instability under continuous heat stress (PubMed:31804502). Belongs to the TDD superfamily. DTWD2 family. TapT subfamily. Extended N-terminus.