Mechanism of MenE Inhibition by Acyl-Adenylate Analogues and Discovery of Novel Antibacterial Agents

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• 作者：Joe S. Matarlo ; Christopher E. Evans ; Indrajeet Sharma ; Lubens J. Lavaud ; Stephen C. Ngo ; Roger Shek ; Kanagalaghatta R. Rajashankar ; Jarrod B. French ; Derek S. Tan ; Peter J. Tonge
• 刊名：Biochemistry
• 出版年：2015
• 出版时间：October 27, 2015
• 年：2015
• 卷：54
• 期：42
• 页码：6514-6524
• 全文大小：547K
• ISSN：1520-4995

文摘

MenE 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 (<b>1b>), which has an ICb>50b> value of 鈮?5 nM for Escherichia coli MenE. Herein, we show that OSB-AMS reduces menaquinone levels in Staphylococcus aureus, consistent with its proposed mechanism of action, despite the observation that the antibacterial activity of OSB-AMS is 鈭?000-fold lower than the ICb>50b> for enzyme inhibition. To inform the synthesis of MenE inhibitors with improved antibacterial activity, we have undertaken a structure鈥揳ctivity 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 (<b>11b>) with improved antibacterial activity was discovered, providing a pathway toward the development of optimized MenE inhibitors in the future.