2imo

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spinqualitylabelsall models 2imo, resolution 2.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of allantoate amidohydrolase from Escherichia coli at pH 4.6

Overview

Purine metabolism plays a major role in regulating the availability of, purine nucleotides destined for nucleic acid synthesis. Allantoate, amidohydrolase catalyzes the conversion of allantoate to, (S)-ureidoglycolate, one of the crucial alternate steps in purine, metabolism. The crystal structure of a ternary complex of allantoate, amidohydrolase with its substrate allantoate and an allosteric effector, a, sulfate ion, from Escherichia coli was determined to understand better the, catalytic mechanism and substrate specificity. The 2.25 A resolution X-ray, structure reveals an alpha/beta scaffold akin to zinc exopeptidases of the, peptidase M20 family and lacks the (beta/alpha)(8)-barrel fold, characteristic of the amidohydrolases. Arrangement of the substrate and, the two co-catalytic zinc ions at the active site governs catalytic, specificity for hydrolysis of N-carbamyl versus the peptide bond in, exopeptidases. In its crystalline form, allantoate amidohydrolase adopts a, relatively open conformation. However, structural analysis reveals the, possibility of a significant movement of domains via rotation about two, hinge regions upon allosteric effector and substrate binding resulting in, a closed catalytically competent conformation by bringing the substrate, allantoate closer to co-catalytic zinc ions. Two cis-prolyl peptide bonds, found on either side of the dimerization domain in close proximity to the, substrate and ligand-binding sites may be involved in protein folding and, in preserving the integrity of the catalytic site.

About this Structure

2IMO is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Structural Analysis of a Ternary Complex of Allantoate Amidohydrolase from Escherichia coli Reveals its Mechanics., Agarwal R, Burley SK, Swaminathan S, J Mol Biol. 2007 Apr 27;368(2):450-63. Epub 2007 Feb 20. PMID:17362992

Page seeded by OCA on Wed Nov 21 12:22:38 2007