tRNA Nucleotidyltransferase 1, Mitochondrial (TRNT1)

The CCA-adding enzyme TRNT1 is an essential enzyme that catalyzes the addition of the CCA terminus to the 3-prime end of tRNA precursors. This reaction is a fundamental prerequisite for mature tRNAs to become aminoacylated and to participate in protein biosynthesis.The deduced 434-amino acid protein has an N-terminal mitochondria-targeting signal sequence and conserved DXD and RRD motifs involved in nucleotide incorporation activity. The mature protein begins with leu27 and has a calculated molecular mass of 47 kD.The T-arm of the substrate tRNA was required for efficient CCA addition by TRNT1. Unlike the E. coli ortholog, human TRNT1 could use both cytoplasmic and mitochondrial tRNA substrates, since it recognized the general T-arm structure rather than a specific sequence.