1dbt
From Proteopedia
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CRYSTAL STRUCTURE OF OROTIDINE 5'-MONOPHOSPHATE DECARBOXYLASE FROM BACILLUS SUBTILIS COMPLEXED WITH UMP
Overview
The crystal structure of Bacillus subtilis orotidine 5'-monophosphate, (OMP) decarboxylase with bound uridine 5'-monophosphate has been, determined by multiple wavelength anomalous diffraction phasing techniques, and refined to an R-factor of 19.3% at 2.4 A resolution. OMP decarboxylase, is a dimer of two identical subunits. Each monomer consists of a, triosephosphate isomerase barrel and contains an active site that is, located across one end of the barrel and near the dimer interface. For, each active site, most of the residues are contributed by one monomer with, a few residues contributed from the adjacent monomer. The most highly, conserved residues are located in the active site and suggest a novel, catalytic mechanism for decarboxylation that is different from any, previously proposed OMP decarboxylase mechanism. The uridine, 5'-monophosphate molecule is bound to the active site such that the, phosphate group is most exposed and the C5-C6 edge of the pyrimidine base, is most buried. In the proposed catalytic mechanism, the ground state of, the substrate is destabilized by electrostatic repulsion between the, carboxylate of the substrate and the carboxylate of Asp60. This repulsion, is reduced in the transition state by shifting negative charge from the, carboxylate to C6 of the pyrimidine, which is close to the protonated, amine of Lys62. We propose that the decarboxylation of OMP proceeds by an, electrophilic substitution mechanism in which decarboxylation and, carbon-carbon bond protonation by Lys62 occur in a concerted reaction.
About this Structure
1DBT is a Single protein structure of sequence from Bacillus subtilis with U5P as ligand. Active as Orotidine-5'-phosphate decarboxylase, with EC number 4.1.1.23 Full crystallographic information is available from OCA.
Reference
The crystal structure and mechanism of orotidine 5'-monophosphate decarboxylase., Appleby TC, Kinsland C, Begley TP, Ealick SE, Proc Natl Acad Sci U S A. 2000 Feb 29;97(5):2005-10. PMID:10681442
Page seeded by OCA on Tue Nov 20 13:08:48 2007
