Institute of Medical Microbiology, Immunology and Parasitology-Pharmaceutical Microbiology Section, University of Bonn, Meckenheimer Allee 168, D-53115 Bonn, Germany.
J Biol Chem. 2012 Jun 8;287(24):20270-80. doi: 10.1074/jbc.M112.369561. Epub 2012 Apr 18.
Empedopeptin is a natural lipodepsipeptide antibiotic with potent antibacterial activity against multiresistant Gram-positive bacteria including methicillin-resistant Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae in vitro and in animal models of bacterial infection. Here, we describe its so far elusive mechanism of antibacterial action. Empedopeptin selectively interferes with late stages of cell wall biosynthesis in intact bacterial cells as demonstrated by inhibition of N-acetylglucosamine incorporation into polymeric cell wall and the accumulation of the ultimate soluble peptidoglycan precursor UDP-N-acetylmuramic acid-pentapeptide in the cytoplasm. Using membrane preparations and the complete cascade of purified, recombinant late stage peptidoglycan biosynthetic enzymes and their respective purified substrates, we show that empedopeptin forms complexes with undecaprenyl pyrophosphate containing peptidoglycan precursors. The primary physiological target of empedopeptin is undecaprenyl pyrophosphate-N-acetylmuramic acid(pentapeptide)-N-acetylglucosamine (lipid II), which is readily accessible at the outside of the cell and which forms a complex with the antibiotic in a 1:2 molar stoichiometry. Lipid II is bound in a region that involves at least the pyrophosphate group, the first sugar, and the proximal parts of stem peptide and undecaprenyl chain. Undecaprenyl pyrophosphate and also teichoic acid precursors are bound with lower affinity and constitute additional targets. Calcium ions are crucial for the antibacterial activity of empedopeptin as they promote stronger interaction with its targets and with negatively charged phospholipids in the membrane. Based on the high structural similarity of empedopeptin to the tripropeptins and plusbacins, we propose this mechanism of action for the whole compound class.
恩佩多肽是一种天然的脂肽抗生素，具有强大的抗菌活性，可有效抵抗体外和动物感染模型中的多种耐甲氧西林金黄色葡萄球菌和青霉素耐药肺炎链球菌等耐革兰氏阳性菌。在此，我们描述了其迄今为止难以捉摸的抗菌作用机制。恩佩多肽选择性地干扰完整细菌细胞中细胞壁生物合成的后期阶段，这表现在抑制 N-乙酰葡萄糖胺掺入聚合细胞壁和细胞质中最终可溶性肽聚糖前体 UDP-N-乙酰胞壁酸-五肽的积累。使用膜制剂以及完整的、纯化的晚期肽聚糖生物合成酶及其各自的纯化底物级联，我们表明恩佩多肽与含有十一烯基焦磷酸的肽聚糖前体形成复合物。恩佩多肽的主要生理靶标是十一烯基焦磷酸-N-乙酰胞壁酸（五肽）-N-乙酰葡萄糖胺（脂质 II），它在细胞外部很容易获得，并且与抗生素以 1:2 摩尔比形成复合物。脂质 II 结合在一个区域，该区域至少涉及焦磷酸基团、第一个糖和肽聚糖和十一烯基链的近端部分。脂质 II 和磷壁酸前体的结合亲和力较低，也是其作用靶点。钙离子对恩佩多肽的抗菌活性至关重要，因为它们促进与靶点和膜中带负电荷的磷脂的更强相互作用。基于恩佩多肽与三肽和 plusbacins 的高度结构相似性，我们提出了整个化合物类别的这种作用机制。
