3O7H

Crystal structure of 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase from Klebsiella pneumoniae

Summary for 3O7H

• Entry DOI: 10.2210/pdb3o7h/pdb
• Related: 3O7I 3O7J 3O7K
• Descriptor: OHCU decarboxylase (2 entities in total)
• Functional Keywords: decarboxylase, lyase
• Biological source: Klebsiella pneumoniae subsp. pneumoniae
• Total number of polymer chains: 2
• Total formula weight: 41666.59

Authors

French, J.B.,Ealick, S.E. (deposition date: 2010-07-30, release date: 2010-09-08, Last modification date: 2023-09-06)

Primary citation

French, J.B.,Ealick, S.E.
Structural and Mechanistic Studies on Klebsiella pneumoniae 2-Oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline Decarboxylase.
J.Biol.Chem., 285:35446-35454, 2010

PubMed Abstract: The stereospecific oxidative degradation of uric acid to (S)-allantoin was recently shown to proceed via three enzymatic steps. The final conversion is a decarboxylation of the unstable intermediate 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline (OHCU) and is catalyzed by OHCU decarboxylase. Here we present the structures of Klebsiella pneumoniae OHCU decarboxylase in unliganded form and with bound allantoin. These structures provide evidence that ligand binding organizes the active site residues for catalysis. Modeling of the substrate and intermediates provides additional support for this hypothesis. In addition we characterize the steady state kinetics of this enzyme and report the first OHCU decarboxylase inhibitor, allopurinol, a structural isomer of hypoxanthine. This molecule is a competitive inhibitor of K. pneumoniae OHCU decarboxylase with a K(i) of 30 ± 2 μM. Circular dichroism measurements confirm structural observations that this inhibitor disrupts the necessary organization of the active site. Our structural and biochemical studies also provide further insights into the mechanism of catalysis of OHCU decarboxylation.

PubMed: 20826786
DOI: 10.1074/jbc.M110.156034

Experimental method

X-RAY DIFFRACTION (1.79 Å)