Reconstitution of Bacterial Targets in Model Membranes for a Biosensor-based Functional Analysis and Screening of Antibiotics

大量抗生素是通过与细菌细胞膜或其中的靶点相互作用来发挥其活性的。原型抗生素nisin在一个分子中结合了两种杀伤机制，抑制细胞壁生物合成和形成特定的膜孔。两者都使用细胞壁前体脂质II作为靶标和锚定分子。我们引入一个平面模型膜系统来模拟化合物的抗生素活性并解释它们的作用方式。石英晶体微天平（QCM）和循环伏安法（CV）这两种组合的生物传感器可以同时或单独实时跟踪抗生素的靶结合和膜透性。动力学结合常数（QCM）的检测可以验证某些膜靶点的作用，如C55P、C55PP、脂质I和脂质II。等温滴定量热法测量将补充结合数据。孔隙形成的CV研究将通过原子力显微镜完成。nisin的研究将扩展到一系列抗生素，以描述这类抗生素的结构-活性关系。此外，这些技术将应用于该联盟中的其他化合物（特别是脂肽，如达托霉素、水蛭霉素或恩培肽），以研究膜靶点和作用方式。基于生物传感器的双作用抗生素结构与功能相关性分析将为新型抗感染药物的设计提供指导。

A large number of antibiotics exert their activity by interacting with bacterial cell membranes or targets therein. The prototype lantibiotic nisin combines two killing mechanisms in one molecule, inhibition of cell wall biosynthesis and formation of specific membrane pores. For both it uses the cell wall precursor lipid II as a target and anchor molecule. We introduce a planar model membrane system to simulate the antibiotic activity of compounds and to interpret their mode of action. Two combined biosensors, quartz crystal microbalance (QCM) and cyclic voltammetry (CV) allow to follow the target binding of and membrane permeabilization by antibiotics in real time, either simultaneously or separately. The detection of kinetic binding constants (QCM) can validate the role of certain membrane targets, such as C55P, C55PP, lipid I and lipid II. Isothermal titration calorimetry measurements will supplement the binding data. CV studies of pore formation will be completed by atomic force microscopy. The investigations with nisin will be extended to a series of lantibiotics to delineate structure-activity relationships within this class of antibiotics. Furthermore, these techniques will be applied to other compounds from the consortium (especially lipopeptides, such as daptomycin, friulimicin or empedopeptin) to study for membrane targets and the mode of action. The biosensor based analysis of structurefunction correlations of dual action antibiotics will give directions for the design of innovative antiinfectives.