MECHANISM AND FUNCTION OF UNIPOLARITY OF SHIGELLA ICSA

描述(改编自申请人摘要)：志贺氏菌属继续 是每年全球范围内痢疾和腹泻的主要原因。志贺氏菌是 在革兰氏阴性肠道病原体中独一无二的是它进入细胞质 并将肌动蛋白组装成长尾，从而推动细菌 通过纸巾传播。调查人员此前曾表示， 志贺氏菌外膜蛋白ICSA足以组装肌动蛋白， ICSA定位于芽孢杆菌的单极。分子机制 参与ICSA单极定位的研究尚不清楚。他们的数据 证明ICSA是直接针对细菌极的。在……里面 与此相结合，他们开发了提供工具的构造 有必要直接解决单极靶向的分子机制 ICSA，这项提案的一个主要目标。相比之下，ICSA是统一的 分布在某些大肠杆菌菌株的表面，能够介导 肌动蛋白尾部组装，不封盖ICSA。这项提议还包括 具体阐述了ICSA的单极本地化在 志贺氏菌的致病机制，他们现在可以进行关键的测试。 这项建议的具体目的是：(1)识别和 ICSA单极所需残基和结构域的表征 定位；(2)志贺氏菌蛋白的鉴定 与ICSA互动并分析其在ICSA单极中的潜在作用 本地化；以及(3)对ICSA单极在志贺氏菌中的作用的评估 发病机制。此应用程序建议获取将提供以下信息的信息 福氏志贺氏菌单极靶向的分子机制研究 毒力因子ICSA。此外，他们的研究将阐明ICSA的作用 志贺氏菌致病机制和毒力的单极性。最后，他们的 研究可能会为我们提供对 介导性三维靶向在细菌和分子中的蛋白质 细菌旧杆与新杆的区别特征 和细菌的侧面。

DESCRIPTION (Adapted from the Applicant's Abstract): Shigella spp. continue to be a leading cause of dysentery and diarrhea annually worldwide. Shigella is unique among Gram-negative enteric pathogens in that it accesses the cytoplasm of host cells and assembles actin into long tails, which propel bacterial spread through tissues. The investigators have previously shown that the Shigella outer membrane protein IcsA is sufficient for actin assembly and that IcsA is localized to a single pole of the bacillus. The molecular mechanisms involved in the unipolar localization of IcsA are unknown. Their data demonstrate that IcsA is directly targeted to the bacterial pole. In conjunction with this, they have developed constructs that provide the tools necessary to directly address the molecular mechanisms of unipolar targeting of IcsA, a major goal of this proposal. In contrast, IcsA that is uniformly distributed over the surface of certain E. coli strains is able to mediate actin tail assembly without capping of the IcsA. This proposal also specifically addresses the function of unipolar localization of IcsA in Shigella pathogenesis, which they are now in a position to test critically. The Specific Aims of this proposal are: (1) the identification and characterization of residues and domains of IcsA required for its unipolar localization; (2) the identification of Shigella proteins that directly interact with IcsA and analysis of their potential role in IcsA unipolar localization; and (3) an assessment of the role of IcsA unipolarity in Shigella pathogenesis. This application proposes to obtain information that will provide insight into the molecular mechanisms of unipolar targeting of the S. flexneri virulence factor IcsA. Further, their studies will elucidate the role of IcsA unipolarity in the pathogenesis and virulence of Shigella. Finally, their studies will likely provide insight into the fundamental mechanisms that mediate three-dimensional targeting of proteins in bacteria and the molecular characteristics of the bacterial old pole that distinguish it from the new pole and the sides of the bacillus.