1x8r
From Proteopedia
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EPSPS liganded with the (S)-phosphonate analog of the tetrahedral reaction intermediate
Overview
The enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) catalyzes, the penultimate step of the shikimate pathway and is the target of the, broad-spectrum herbicide glyphosate. Since the functionality of the, shikimate pathway is vital not only for plants but also for, microorganisms, EPSPS is considered a prospective target for the, development of novel antibiotics. We have kinetically analyzed and, determined the crystal structures of Escherichia coli EPSPS inhibited by, (R)- and (S)-configured phosphonate analogues of the tetrahedral reaction, intermediate. Both diastereomers are competitive inhibitors with respect, to the substrates of the EPSPS reaction, shikimate-3-phosphate (S3P) and, phosphoenolpyruvate (PEP). Remarkably, the (S)-phosphonate (K(iS3P) = 750, nM), whose configuration corresponds to that of the genuine tetrahedral, intermediate, is a much weaker inhibitor than the (R)-phosphonate analogue, (K(iS3P) = 16 nM). The crystal structures of EPSPS liganded with the (S)-, and (R)-phosphonates, at 1.5 and 1.9 A resolution, respectively, revealed, that binding of the (R)-phosphonate induces conformational changes of the, strictly conserved residues Arg124 and Glu341 within the active site. This, appears to give rise to substantial structural alterations in the, amino-terminal globular domain of the enzyme. By contrast, binding of the, (S)-phosphonate renders the enzyme structure unchanged. Thus, EPSPS may, facilitate the tight binding of structurally diverse ligands through, conformational flexibility. Molecular docking calculations did not explain, why the (R)-phosphonate is the better inhibitor. Therefore, we propose, that the structural events during the open-closed transition of EPSPS are, altered as a result of inhibitor action.
About this Structure
1X8R is a Single protein structure of sequence from Escherichia coli with SC1 and FMT as ligands. Active as 3-phosphoshikimate 1-carboxyvinyltransferase, with EC number 2.5.1.19 Full crystallographic information is available from OCA.
Reference
Interaction of phosphonate analogues of the tetrahedral reaction intermediate with 5-enolpyruvylshikimate-3-phosphate synthase in atomic detail., Priestman MA, Healy ML, Becker A, Alberg DG, Bartlett PA, Lushington GH, Schonbrunn E, Biochemistry. 2005 Mar 8;44(9):3241-8. PMID:15736934
Page seeded by OCA on Wed Nov 21 05:54:14 2007
