CATH Classification

Domain Context

CATH Clusters

Superfamily 3.30.70.3000
Functional Family tRNA(His) guanylyltransferase

Enzyme Information

2.7.7.79
tRNA(His) guanylyltransferase.
based on mapping to UniProt Q9NWX6
p-tRNA(His) + ATP + GTP + H(2)O = pG-P-tRNA(His) + AMP + 2 diphosphate.
-!- In eukarya an additional guanosine residue is added post- transcriptionally to the 5'-end of tRNA(His) molecules. -!- The addition occurs opposite a universally conserved adenosine(73) and is thus the result of a non-templated 3'-5' addition reaction. -!- The additional guanosine residue is an important determinant for aminoacylation by EC 6.1.1.21. -!- The enzyme requires a divalent cation for activity. -!- ATP activation is not required when the substrate contains a 5'-triphosphate (ppp-tRNA(His)).

UniProtKB Entries (1)

Q9NWX6
THG1_HUMAN
Homo sapiens
Probable tRNA(His) guanylyltransferase

PDB Structure

PDB 3OTC
External Links
Method X-RAY DIFFRACTION
Organism
Primary Citation
tRNAHis guanylyltransferase (THG1), a unique 3'-5' nucleotidyl transferase, shares unexpected structural homology with canonical 5'-3' DNA polymerases.
Hyde, S.J., Eckenroth, B.E., Smith, B.A., Eberley, W.A., Heintz, N.H., Jackman, J.E., Doublie, S.
Proc.Natl.Acad.Sci.USA