1E77

COMPLEX OF ACTIVE MUTANT (Q365->C) OF GLUCOSE 6-PHOSPHATE DEHYDROGENASE FROM LEUCONOSTOC MESENTEROIDES WITH SUBSTRATE

Summary for 1E77

• Entry DOI: 10.2210/pdb1e77/pdb
• Related: 1DPG 1E7M 1E7Y 2DPG
• Descriptor: GLUCOSE 6-PHOSPHATE 1-DEHYDROGENASE, 6-O-phosphono-beta-D-glucopyranose, CALCIUM ION, ... (4 entities in total)
• Functional Keywords: oxidoreductase, oxidoreductase (choh(d) - nad(p)), glucose metabolism
• Biological source: LEUCONOSTOC MESENTEROIDES
• Total number of polymer chains: 1
• Total formula weight: 54644.87

Authors

Adams, M.J.,Vandeputte-Rutten, L.,Gover, S. (deposition date: 2000-08-24, release date: 2000-12-11, Last modification date: 2024-05-01)

Primary citation

Cosgrove, M.S.,Gover, S.,Naylor, C.E.,Vandeputte-Rutten, L.,Adams, M.J.,Levy, H.R.
An Examination of the Role of Asp-177 in the His-Asp Catalytic Dyad of Leuconostoc Mesenteroides Glucose 6-Phosphate Dehydrogenase: X-Ray Structure and Ph Dependence of Kinetic Parameters of the D177N Mutant Enzyme
Biochemistry, 39:15002-, 2000

PubMed Abstract: The role of Asp-177 in the His-Asp catalytic dyad of glucose 6-phosphate dehydrogenase from Leuconostoc mesenteroides has been investigated by a structural and functional characterization of the D177N mutant enzyme. Its three-dimensional structure has been determined by X-ray cryocrystallography in the presence of NAD(+) and in the presence of glucose 6-phosphate plus NADPH. The structure of a glucose 6-phosphate complex of a mutant (Q365C) with normal enzyme activity has also been determined and substrate binding compared. To understand the effect of Asp-177 on the ionization properties of the catalytic base His-240, the pH dependence of kinetic parameters has been determined for the D177N mutant and compared to that of the wild-type enzyme. The structures give details of glucose 6-phosphate binding and show that replacement of the Asp-177 of the catalytic dyad with asparagine does not affect the overall structure of glucose 6-phosphate dehydrogenase. Additionally, the evidence suggests that the productive tautomer of His-240 in the D177N mutant enzyme is stabilized by a hydrogen bond with Asn-177; hence, the mutation does not affect tautomer stabilization. We conclude, therefore, that the absence of a negatively charged aspartate at 177 accounts for the decrease in catalytic activity at pH 7.8. Structural analysis suggests that the pH dependence of the kinetic parameters of D177N glucose 6-phosphate dehydrogenase results from an ionized water molecule replacing the missing negative charge of the mutated Asp-177 at high pH. Glucose 6-phosphate binding orders and orients His-178 in the D177N-glucose 6-phosphate-NADPH ternary complex and appears to be necessary to form this water-binding site.

PubMed: 11106478
DOI: 10.1021/BI0014608

Experimental method

X-RAY DIFFRACTION (2.69 Å)