2DG5: Crystal Structure Of Gamma-Glutamyl Transpeptidase From Escherichia Coli In Complex With Hydrolyzed Glutathione

Citation:
Abstract
Gamma-glutamyltranspeptidase (GGT) is a heterodimic enzyme that is generated from the precursor protein through posttranslational processing and catalyzes the hydrolysis of gamma-glutamyl bonds in gamma-glutamyl compounds such as glutathione and/or the transfer of the gamma-glutamyl group to other amino acids and peptides. We have determined the crystal structure of GGT from Escherichia coli K-12 at 1.95 A resolution. GGT has a stacked alphabetabetaalpha fold comprising the large and small subunits, similar to the folds seen in members of the N-terminal nucleophile hydrolase superfamily. The active site Thr-391, the N-terminal residue of the small subunit, is located in the groove, from which the pocket for gamma-glutamyl moiety binding follows. We have further determined the structure of the gamma-glutamyl-enzyme intermediate trapped by flash cooling the GGT crystal soaked in glutathione solution and the structure of GGT in complex with l-glutamate. These structures revealed how the gamma-glutamyl moiety and l-glutamate are recognized by the enzyme. A water molecule was seen on the carbonyl carbon of the gamma-glutamyl-Thr-391 Ogamma bond in the intermediate that is to be hydrolyzed. Notably the residues essential for GGT activity (Arg-114, Asp-433, Ser-462, and Ser-463 in E. coli GGT) shown by site-directed mutagenesis of human GGT are all involved in the binding of the gamma-glutamyl moiety. The structure of E. coli GGT presented here, together with sequence alignment of GGTs, may be applicable to interpret the biochemical and genetic data of other GGTs.
PDB ID: 2DG5Download
MMDB ID: 38662
PDB Deposition Date: 2006/3/8
Updated in MMDB: 2012/10
Experimental Method:
x-ray diffraction
Resolution: 1.6  Å
Source Organism:
Similar Structures:
Biological Unit for 2DG5: dimeric; determined by author and by software (PISA)
Molecular Components in 2DG5
Label Count Molecule
Proteins (2 molecules)
1
Gamma-glutamyltranspeptidase(Gene symbol: ggt)
Molecule annotation
1
Gamma-glutamyltranspeptidase(Gene symbol: ggt)
Molecule annotation
Chemicals (3 molecules)
1
1
2
1
3
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.