5c5h
R195K E. coli MenE with bound OSB-AMS
Structural highlights
FunctionMENE_ECOLI Converts 2-succinylbenzoate (OSB) to 2-succinylbenzoyl-CoA (OSB-CoA).[HAMAP-Rule:MF_00731][1] Publication Abstract from PubMedMenE is an o-succinylbenzoyl-CoA (OSB-CoA) synthetase in the bacterial menaquinone biosynthesis pathway and is a promising target for the development of novel antibacterial agents. The enzyme catalyzes CoA ligation via an acyl-adenylate intermediate, and we have previously reported tight-binding inhibitors of MenE based on stable acyl-sulfonyladenosine analogues of this intermediate, including OSB-AMS (1) which has an IC50 value of </= 25 nM for the Escherichia coli MenE. Herein, we show that OSB-AMS reduces menaquinone levels in S. aureus, consistent with its proposed mechanism of action, despite the observation that the antibacterial activity of OSB-AMS is ~1000-fold lower than the IC50 for enzyme inhibition. To inform the synthesis of MenE inhibitors with improved antibacterial activity, we have undertaken a structure-activity relationship (SAR) study stimulated by the knowledge that OSB-AMS can adopt two isomeric forms in which the OSB side chain exists either as an open-chain keto acid or a cyclic lactol. These studies revealed that negatively charged analogues of the keto-acid form bind, while neutral analogues do not, consistent with the hypothesis that the negatively-charged keto-acid form of OSB-AMS is the active isomer. X-ray crystallography and site-directed mutagenesis confirm the importance of a conserved arginine for binding the OSB carboxylate. Although most lactol isomers tested were inactive, a novel difluoroindanediol inhibitor (11) with improved antibacterial activity was discovered, providing a pathway toward the development of optimized MenE inhibitors in the future. Mechanism of MenE Inhibition by Acyl-Adenylate Analogues and Discovery of Novel Antibacterial Agents.,Matarlo JS, Evans CE, Sharma I, Lavaud LJ, Ngo SC, Shek R, Rajashankar KR, French JB, Tan DS, Tonge PJ Biochemistry. 2015 Sep 22. PMID:26394156[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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