Dynamic Properties of Bacterial Adhesins

描述（由申请人提供）：在这个竞争性更新申请中提出的研究旨在分析拉伸机械力如何增加一些最常见的细菌粘附素结合碳水化合物配体的能力，即介导受体-配体相互作用的捕获键机制。我们目前的生物工程研究伙伴关系资助项目表明，剪切应力的存在显著增强了大肠杆菌甘露糖特异性、fimh介导的粘附强度。我们已经证明，FimH粘附素是一种变构调节蛋白，其中甘露糖配体与FimH结合袋相互作用的诱导配合机制与FimH的甘露糖结合结构域和纤维结合结构域之间的分离构象相关联，这是拉伸机械力所偏爱的构型。在更新应用中，我们建议使用核磁共振（NMR）光谱、原子力显微镜（AFM）和分子动力学模拟（MD/SMD）等方法来全面了解配体活化FimH过程中的构象转移以及张力对这一过程的促进作用。我们将利用这些知识开发防止医学相关细菌粘附到宿主靶细胞和表面的策略，开发剪切调节纳米技术工具，并作为理解其他类型剪切依赖细菌粘附的范例。

DESCRIPTION (provided by applicant): Studies proposed in this competing renewal application are intended to dissect how tensile mechanical force increases ability of some of the most common bacterial adhesins to bind carbohydrate ligands, i.e. mediate catch-bond mechanism of receptor-ligand interaction. Our current Bioengineering Research Partnership grant project has demonstrated that the strength of mannose-specific, FimH-mediated adhesion of Escherichia coli is dramatically enhanced by the presence of shear stress. We have shown that FimH adhesin is an allosterically regulated protein, where induced-fit mechanism of interaction of the mannose ligand with the FimH binding pocket is conformationally linked with separation between mannose-binding and fimbria-incorporating domains of FimH - the configuration favored by tensile mechanical force. In the renewal application, we propose to use, among other approaches, nuclear magnetic resonance (NMR) spectroscopy and atomic force microscopy (AFM) and molecular dynamics simulation (MD/SMD) to derive a comprehensive understanding of the conformational shift in course of FimH activation by the ligand and facilitation of this process by tensile force. We will use this knowledge for developing strategies on preventing adhesion of medically-relevant bacteria to host target cells and surfaces, for developing shear- modulated nanotechnological tools, and as a paradigm for understanding other types of shear-dependent bacterial adhesion.