CHARACTERIZATION OF THE TYPE IV PILUS MOTOR COMPLEX

IV型皮利是许多细菌表面上显示的细长细丝。它们具有多种功能，这些功能依赖于它们的以下能力：（i）粘附于各种基质，包括宿主细胞表面、来自附近细菌的皮利、DNA和噬菌体，以及（ii）去粘附或缩回，其沿着粘膜表面牵拉细菌沿着，将它们拉在一起形成保护性聚集体，并且可以将基质如DNA和噬菌体吸引到细菌中以获得营养和遗传变异。IV型皮利是数千个拷贝的主要菌毛蛋白亚基的聚合物。皮利通过一个复杂的分子机器在内膜上组装，该分子机器从细胞质到外膜跨越细菌包膜。我们的实验室是在这一领域的最前沿，与我们的IV型菌毛蛋白亚基的X射线晶体结构和完整的菌毛细丝的冷冻电子显微镜重建提供了这些细胞器的原子分辨率图片和理解细丝组装的框架。许多研究小组在了解菌毛组装装置的结构方面取得了显著的进展，但这些皮利组装的机制仍然是一个谜。这项建议的目的是表征菌毛机械内的分子马达复合物，以揭示它如何驱动细丝组装。

Type IV pili are long thin filaments displayed on the surfaces of many bacteria. They have a diverse array of functions that rely on their ability to (i) adhere to various substrates, including host cell surfaces, pili from nearby bacteria, DNA and bacteriophage, and (ii) to depolymerize or retract, which pulls the bacteria along mucosal surfaces, pulls them close together in protective aggregates, and can draw substrates like DNA and phage into the bacterium for nutrition and genetic variation. Type IV pili are polymers of thousands of copies of the major pilin subunit. The pili are assembled at the inner membrane by a complex molecular machine spanning the bacterial envelope from the cytoplasm to the outer membrane. Our lab is at the forefront of this field, with our x-ray crystal structures of Type IV pilin subunits and cryo-electron microscopy reconstructions of intact pilus filaments providing an atomic resolution picture of these organelles and a framework for understanding filament assembly. Remarkable progress has been made by many groups in understanding the architecture of the pilus assembly apparatus, yet the mechanism by which these pili are assembled remains a mystery. This proposal aims to characterize the molecular motor complex within the pilus machinery to reveal how it drives filament assembly.