1Z2L: Crystal Structure Of Allantoate-Amidohydrolase From E.Coli K12 In Complex With Substrate Allantoate

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.
PDB ID: 1Z2LDownload
MMDB ID: 32621
PDB Deposition Date: 2005/3/8
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 2.25  Å
Source Organism:
Similar Structures:
Biological Unit for 1Z2L: dimeric; determined by author and by software (PISA)
Molecular Components in 1Z2L
Label Count Molecule
Proteins (2 molecules)
Allantoate Amidohydrolase(Gene symbol: allC)
Molecule annotation
Chemicals (7 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB