1x8t
EPSPS liganded with the (R)-phosphonate analog of the tetrahedral reaction intermediate
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
| ||||||||||||||||||||
