2DBX

Crystal Structure of Gamma-glutamyltranspeptidase from Escherichia coli Complexed with L-Glutamate

Summary for 2DBX

• Entry DOI: 10.2210/pdb2dbx/pdb
• Related: 2DBU 2DBW
• Descriptor: Gamma-glutamyltranspeptidase, GLYCEROL, CALCIUM ION, ... (6 entities in total)
• Functional Keywords: gamma-glutamyltransferase, ggt, gamma-gtp, glutathione, transferase
• Biological source: Escherichia coli K12; More
• Cellular location: Periplasm: P18956 P18956
• Total number of polymer chains: 4
• Total formula weight: 120646.55

Authors

Okada, T.,Wada, K.,Fukuyama, K. (deposition date: 2005-12-16, release date: 2006-04-18, Last modification date: 2023-11-15)

Primary citation

Okada, T.,Suzuki, H.,Wada, K.,Kumagai, H.,Fukuyama, K.
Crystal structures of gamma-glutamyltranspeptidase from Escherichia coli, a key enzyme in glutathione metabolism, and its reaction intermediate.
Proc.Natl.Acad.Sci.Usa, 103:6471-6476, 2006

PubMed 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.

PubMed: 16618936
DOI: 10.1073/pnas.0511020103

Experimental method

X-RAY DIFFRACTION (1.7 Å)