InterPro domain: IPR029062

This superfamily represents the class I glutamine amidotransferase-like domain.

Glutamine amidotransferase (GATase) enzymes catalyse the removal of the ammonia group from glutamine and then transfer this group to a substrate to form a new carbon-nitrogen group [ 1 ]. The GATase domain exists either as a separate polypeptidic subunit or as part of a larger polypeptide fused in different ways to a synthase domain. Two classes of GATase domains have been identified [ 2 , 3 ]: class-I (also known as trpG-type or triad) and class-II (also known as purF-type or Ntn). In class I glutamine amidotransferases, a triad of conserved Cys-His-Glu forms the active site, wherein the catalytic cysteine is essential for the amidotransferase activity [ 4 , 5 ]. Different structures show that the active site Cys of type 1 GATase is located at the tip of a nucleophile elbow.

This entry also include the DJ-1/PfpI protein that contains a catalytic triad or dyad different from the class I GAT triad.

1. The amidotransferases. Adv. Enzymol. Relat. Areas Mol. Biol. 39, 91-183
2. Structural role for a conserved region in the CTP synthetase glutamine amide transfer domain. J. Bacteriol. 169, 3023-8
3. Sequence of the small subunit of yeast carbamyl phosphate synthetase and identification of its catalytic domain. J. Biol. Chem. 259, 9790-8
4. The crystal structure of GMP synthetase reveals a novel catalytic triad and is a structural paradigm for two enzyme families. Nat. Struct. Biol. 3, 74-86
5. The mechanism of glutamine-dependent amidotransferases. Cell. Mol. Life Sci. 54, 205-22