STRUCTURAL MOTIF MEDIATES FORMATION OF THE PERIPLASMIC RINGS IN THE T3SS

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 III型分泌系统（T3 SS）是允许细菌病原体将毒力蛋白转运到真核宿主细胞中的大分子“注射体”。这种大分子复合物由跨越两种细菌膜的连接环状结构组成。外膜分泌素EscC和内膜蛋白PrgH的周质结构域的晶体结构揭示了形成T3 SS的外膜和内膜环的三种蛋白质之间的模块化折叠的保守性。这导致了这样一种假设，即这种保守的折叠提供了一个共同的环构建基序，该基序允许组装T3 SS特征性的双层外膜和内膜环。使用一个综合的结构和实验方法，我们产生环模型的周质域的ESCC，并将它们放置在组装的T3 SS的上下文中，外膜和内膜环组件和前所未有的跨度外膜分泌素之间的直接相互作用提供了证据。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The type III secretion system (T3SS) is a macromolecular 'injectisome' that allows bacterial pathogens to transport virulence proteins into the eukaryotic host cell. This macromolecular complex is composed of connected ring-like structures that span both bacterial membranes. The crystal structures of the periplasmic domain of the outer membrane secretin EscC and the inner membrane protein PrgH reveal the conservation of a modular fold among the three proteins that form the outer membrane and inner membrane rings of the T3SS. This leads to the hypothesis that this conserved fold provides a common ring-building motif that allows for the assembly of the variably sized outer membrane and inner membrane rings characteristic of the T3SS. Using an integrated structural and experimental approach, we generated ring models for the periplasmic domain of EscC and placed them in the context of the assembled T3SS, providing evidence for direct interaction between the outer membrane and inner membrane ring components and an unprecedented span of the outer membrane secretin.