2dwu | pdb_00002dwu
Crystal Structure of Glutamate Racemase Isoform RacE1 from Bacillus anthracis
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Overview
Glutamate racemase (RacE) is responsible for converting l-glutamate to, d-glutamate, which is an essential component of peptidoglycan, biosynthesis, and the primary constituent of the poly-gamma-d-glutamate, capsule of the pathogen Bacillus anthracis. RacE enzymes are essential for, bacterial growth and lack a human homolog, making them attractive targets, for the design and development of antibacterial therapeutics. We have, cloned, expressed and purified the two glutamate racemase isozymes, RacE1, and RacE2, from the B. anthracis genome. Through a series of steady-state, kinetic studies, and based upon the ability of both RacE1 and RacE2 to, catalyze the rapid formation of d-glutamate, we have determined that RacE1, and RacE2 are bona fide isozymes. The X-ray structures of B. anthracis, RacE1 and RacE2, in complex with d-glutamate, were determined to, resolutions of 1.75 A and 2.0 A. Both enzymes are dimers with monomers, arranged in a "tail-to-tail" orientation, similar to the B. subtilis RacE, structure, but differing substantially from the Aquifex pyrophilus RacE, structure. The differences in quaternary structures produce differences in, the active sites of racemases among the various species, which has, important implications for structure-based, inhibitor design efforts, within this class of enzymes. We found a Val to Ala variance at the, entrance of the active site between RacE1 and RacE2, which results in the, active site entrance being less sterically hindered for RacE1. Using a, series of inhibitors, we show that this variance results in differences in, the inhibitory activity against the two isozymes and suggest a strategy, for structure-based inhibitor design to obtain broad-spectrum inhibitors, for glutamate racemases.
About this Structure
2DWU is a Single protein structure of sequence from Bacillus anthracis with K, DGL and GOL as ligands. Active as Glutamate racemase, with EC number 5.1.1.3 Full crystallographic information is available from OCA.
Reference
Structural and Functional Analysis of Two Glutamate Racemase Isozymes from Bacillus anthracis and Implications for Inhibitor Design., May M, Mehboob S, Mulhearn DC, Wang Z, Yu H, Thatcher GR, Santarsiero BD, Johnson ME, Mesecar AD, J Mol Biol. 2007 Aug 31;371(5):1219-37. Epub 2007 Jun 4. PMID:17610893
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