PMID: 21926168 , Related PDB ids: 2ZK9, 3A54, 3A55, 3A56

Authors:

Hashizume R, Maki Y, Mizutani K, Takahashi N, Matsubara H, Sugita A, Sato K, Yamaguchi S, Mikami B

Title:

Crystal structures of protein glutaminase and its pro forms converted into enzyme-substrate complex.

Journal:

J Biol Chem. 2011 Nov 4;286(44):38691-702. Epub 2011 Sep 16.

Abstract:

Protein glutaminase, which converts a protein glutamine residue to a glutamate residue, is expected to be useful as a new food-processing enzyme. The crystal structures of the mature and pro forms of the enzyme were refined at 1.15 and 1.73 A resolution, respectively. The overall structure of the mature enzyme has a weak homology to the core domain of human transglutaminase-2. The catalytic triad (Cys-His-Asp) common to transglutaminases and cysteine proteases is located in the bottom of the active site pocket. The structure of the recombinant pro form shows that a short loop between S2 and S3 in the proregion covers and interacts with the active site of the mature region, mimicking the protein substrate of the enzyme. Ala-47 is located just above the pocket of the active site. Two mutant structures (A47Q-1 and A47Q-2) refined at 1.5 A resolution were found to correspond to the enzyme-substrate complex and an S-acyl intermediate. Based on these structures, the catalytic mechanism of protein glutaminase is proposed.