The Type 3 Secretion System Translocon Pore in Bacterial Pathogenesis

摘要 3型分泌系统（T3SS）由大约30种不同的细菌病原体表达。他们是 T3SS是这些生物体在人类中的毒力所必需的，但T3SS功能所需的机制是 不完全理解。T3SS在哺乳动物细胞的膜中形成易位子孔。这个毛孔是 T3SS转运细菌效应蛋白穿过哺乳动物细胞膜进入细胞所需的 胞质液孔支持效应子转运所需的分子机制很差， 介绍了志贺氏菌是一种细菌病原体，其需要T3SS来侵入细胞，然后扩散到细胞内。 相邻的细胞在入侵时，易位孔与哺乳动物中间丝相互作用，以支持 T3SS功能。相比之下，我的初步数据显示志贺氏菌传播到邻近细胞发生 独立于中间细丝。这些结果表明，在离散的情况下， 志贺氏菌感染的阶段。本项目的总体目标是研究易位子孔 支持志贺氏菌感染。我提出以下具体目标： 目的1：研究IpaC与中间纤维相互作用导致 对接 目的2：测试IpaC卷曲螺旋结构域是否参与对接所需的过程。 目的3：研究志贺菌易位孔在细胞间传播中的作用。 在这个项目的第一阶段，我将开发技术和方法来研究细菌蛋白质 包含福氏志贺菌易位孔。该奖项的第一阶段将在以下实验室进行： 博士玛西亚戈德堡在马萨诸塞州总医院和哈佛医学院。职业发展 将实施一项计划，强调额外的培训和指导，以使我在 这个项目的独立阶段。作为一名独立调查员，我将联合收割机结合我以前的培训与新的 完成剩余研究目标的能力。这个提议是为了让我实现我的长期目标- 长期的研究目标，并获得独立资助的教师职位，重点是定义细菌 毒力机制和利用这些机制开发新的治疗方法来阻断感染。 !

Abstract Type 3 secretion systems (T3SSs) are expressed by approximately 30 different bacterial pathogens. They are essential for the virulence of these organisms in humans, yet the mechanisms required for T3SS function are incompletely understood. T3SSs form translocon pores in the membranes of mammalian cells. This pore is required for the T3SS to translocate bacterial effector proteins across the mammalian membrane into the cell cytosol. The molecular mechanisms required for the pore to support effector translocation are poorly described. Shigella is a bacterial pathogen that requires a T3SS both to invade cells and then to spread into adjacent cells. At invasion, the translocon pore interacts with mammalian intermediate filaments to support T3SS function. In contrast, my preliminary data show Shigella spread into neighboring cells occurs independent of intermediate filaments. These results suggest translocon pore function is different at discrete stages of Shigella infection. The overall goals of this project are to investigate how the translocon pore supports Shigella infection. I propose the following specific aims: Aim 1: To investigate the mechanisms by which interaction of IpaC with intermediate filaments leads to docking. Aim 2: To test whether the IpaC coiled-coil domain participates in processes required for docking. Aim 3: To characterize the function of the translocon pore during cell-to-cell spread of Shigella. During Phase 1 of this project, I will develop techniques and approaches to investigate the bacterial proteins that comprise the Shigella flexneri translocon pore. Phase 1 of this award will be carried out in the laboratory of Dr. Marcia Goldberg at Massachusetts General Hospital and Harvard Medical School. A career development plan will be implemented emphasizing additional training and mentoring to prepare me for and during the independent phase of this project. As an independent investigator, I will combine my previous training with new skills to complete the remaining research objectives. This proposal is designed to allow me to achieve my long- term research goals and to attain an independently funded faculty position that focuses on defining bacterial virulence mechanisms and on exploiting these mechanisms to develop novel therapeutics to block infection. !