2BZN image
Entry Detail
PDB ID:
2BZN
Keywords:
Title:
Crystal structure of human guanosine monophosphate reductase 2 GMPR2 in complex with IMP
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2005-08-19
Release Date:
2005-09-02
Method Details:
Experimental Method:
Resolution:
2.15 Å
R-Value Free:
0.21
R-Value Work:
0.15
R-Value Observed:
0.16
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:GMP REDUCTASE 2
Chain IDs:A, B, C, D, E, F, G, H
Chain Length:351
Number of Molecules:8
Biological Source:HOMO SAPIENS
Ligand Molecules
Primary Citation
Cofactor Mobility Determines Reaction Outcome in the Impdh and Gmpr (Beta-Alpha)(8) Barrel Enzymes.
Nat.Chem.Biol. 7 950 ? (2011)
PMID: 22037469 DOI: 10.1038/NCHEMBIO.693

Abstact

Inosine monophosphate dehydrogenase (IMPDH) and guanosine monophosphate reductase (GMPR) belong to the same structural family, share a common set of catalytic residues and bind the same ligands. The structural and mechanistic features that determine reaction outcome in the IMPDH and GMPR family have not been identified. Here we show that the GMPR reaction uses the same intermediate E-XMP* as IMPDH, but in this reaction the intermediate reacts with ammonia instead of water. A single crystal structure of human GMPR type 2 with IMP and NADPH fortuitously captures three different states, each of which mimics a distinct step in the catalytic cycle of GMPR. The cofactor is found in two conformations: an 'in' conformation poised for hydride transfer and an 'out' conformation in which the cofactor is 6 Å from IMP. Mutagenesis along with substrate and cofactor analog experiments demonstrate that the out conformation is required for the deamination of GMP. Remarkably, the cofactor is part of the catalytic machinery that activates ammonia.

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