STRUCTURAL MOTIF MEDIATES FORMATION OF THE PERIPLASMIC RINGS IN THE T3SS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 III型分泌系统(T3SS)是一个大分子“注射体”，允许细菌病原体将毒力蛋白输送到真核宿主细胞中。这种大分子复合体由跨越两个细菌膜的连接的环状结构组成。T3SS外膜分泌素ESCC和内膜蛋白PrgH的周质结构域的晶体结构表明，形成T3SS外膜和内膜环的三种蛋白质之间存在一个模块折叠。这导致了一种假设，即这个保守的折叠提供了一个共同的建环基序，允许组装T3SS特有的大小可变的外膜和内膜环。利用结构和实验相结合的方法，我们为ESCC的周质结构域生成了环模型，并将它们放置在组装的T3SS的上下文中，为外膜和内膜环组件之间的直接相互作用以及外膜分泌素的前所未有的跨度提供了证据。

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.