MetaCyc

Parent Class:

EC-Numbers → 2 -- Transferases → 2.7 -- Transferring phosphorous-containing groups → 2.7.7 -- Nucleotidyltransferases

Synonyms: CCA-adding enzyme, tRNA adenylyltransferase, tRNA cytidylyltransferase, tRNA CCA-pyrophosphorylase, tRNA-nucleotidyltransferase, transfer-RNA nucleotidyltransferase, transfer ribonucleic acid nucleotidyl transferase, CTP(ATP):tRNA nucleotidyltransferase, transfer ribonucleate adenylyltransferase, transfer ribonucleate adenyltransferase, transfer RNA adenylyltransferase, transfer ribonucleate nucleotidyltransferase, ATP (CTP):tRNA nucleotidyltransferase, ribonucleic cytidylic cytidylic adenylic pyrophosphorylase, transfer ribonucleic adenylyl (cytidylyl) transferase, transfer ribonucleic-terminal trinucleotide nucleotidyltransferase, transfer ribonucleate cytidylyltransferase, ribonucleic cytidylyltransferase, -C-C-A pyrophosphorylase, ATP(CTP)-tRNA nucleotidyltransferase, tRNA adenylyl(cytidylyl)transferase, CTP:tRNA cytidylyltransferase

Systematic Name: CTP,CTP,ATP:tRNA cytidylyl,cytidylyl,adenylyltransferase

Unification Links: BRENDA:2.7.7.72, ENZYME:2.7.7.72, IUBMB-ExplorEnz:2.7.7.72

Supersedes EC numbers: 2.7.7.25, 2.7.7.21

Reaction:
tRNA precursor + 2 CTP + ATP → tRNA containing a 3' CCA end + 3 diphosphate

Enzymes and Genes:
fused CCA tRNA nucleotidyltransferase/phosphohydrolase: cca ( Escherichia coli K-12 substr. MG1655 )

Summary:
The acylation of all tRNAs with an amino acid occurs at the terminal ribose of a 3' CCA sequence. The CCA sequence is added to the tRNA precursor by stepwise nucleotide addition performed by a single enzyme that is ubiquitous in all living organisms. Although the enzyme has the option of releasing the product after each addition, it prefers to stay bound to the product and proceed with the next addition [Hou10].

Citations: [Schofield77, Shi98, Augustin03, Yakunin04]