UniProt functional annotation for Q7SIB1

UniProt code: Q7SIB1.

Organism:		Geobacillus stearothermophilus (Bacillus stearothermophilus).
Taxonomy:		Bacteria; Firmicutes; Bacilli; Bacillales; Bacillaceae; Geobacillus.
Function:		Catalyzes the addition and repair of the essential 3'- terminal CCA sequence in tRNAs without using a nucleic acid template. Adds these three nucleotides in the order of C, C, and A to the tRNA nucleotide-73, using CTP and ATP as substrates and producing inorganic pyrophosphate.
Catalytic activity:		Reaction=a tRNA precursor + ATP + 2 CTP = a tRNA with a 3' CCA end + 3 diphosphate; Xref=Rhea:RHEA:14433, Rhea:RHEA-COMP:10465, Rhea:RHEA- COMP:10468, ChEBI:CHEBI:30616, ChEBI:CHEBI:33019, ChEBI:CHEBI:37563, ChEBI:CHEBI:74896, ChEBI:CHEBI:83071; EC=2.7.7.72;
Cofactor:		Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Evidence={ECO:0000250};
Subunit:		Homodimer. {ECO:0000269|PubMed:12526808}.
Domain:		The crystal structure reveals a seahorse-shaped subunit consisting of four domains: head, neck, body, and tail. The head domain contains the nucleotidyltransferase activity. The neck domain provides a specific template for the incoming ATP or CTP, whereas the body and tail domains may be involved in tRNA binding.
Miscellaneous:		A single active site specifically recognizes both ATP and CTP and is responsible for their addition.
Similarity:		Belongs to the tRNA nucleotidyltransferase/poly(A) polymerase family. Bacterial CCA-adding enzyme type 3 subfamily. {ECO:0000305}.

Annotations taken from UniProtKB at the EBI.