Shigella IcsA Activation of Actin Assembly by N-WASP

描述（由申请人提供） 志贺菌是细菌性病原体， 全球每年有1.63亿例腹泻和痢疾病例， 主要发生在儿童身上。志贺氏菌通过侵入和传播致病 穿过结肠上皮志贺氏菌通过进入细胞质传播 宿主细胞并诱导肌动蛋白尾在细菌体上的组装。 肌动蛋白尾的形成涉及细菌募集细胞肌动蛋白组装 机械.戈德堡博士的实验室已经证明志贺氏菌蛋白 ICSA足以介导这一过程。ICSA利用细胞Cdc 42 肌动蛋白组装的信号转导途径，已被证明是 在丝状伪足形成中起重要作用。这种细胞途径涉及Cdc 42 Wiskott-Aldrich综合征蛋白（WASP）家族成员的活化。 活化的WASP家族成员激活Arp 213复合物使肌动蛋白成核， 新的纤维，Arp 2/3以700度角交联， 预先存在的细丝。已知IcsA绑定WASP的成员N-WASP 家族，但其激活N-WASP的机制尚不清楚。ICSA是 志贺氏菌毒力所必需的。我们建议描述的机制 lcsA激活N-WASP。我们将鉴定N-WASP和lcsA的残基， 对N-WASP的lcsA结合或lcsA活化都很重要。然后我们将 测试N-WASP是否被lcsA以类似于其激活的方式激活 cdc42这些研究将提供深入了解这两种分子机制 志贺菌致病机理及0 dc 42介导的肌动蛋白分子机制 组装件.

DESCRIPTION (provided by applicant) Shigella spp. are bacterial pathogens that cause an estimated I million deaths and 163 million cases of diarrhea and dysentery annually worldwide, predominantly in children. Shigella cause disease by invading and spreading through the colonic epithelium. Shigella spread by entering the cytoplasm of the host cell and inducing the assembly of an actin tail on the bacterial body. Actin tail formation involves bacterial recruitment of cellular actin assembly machinery. Dr. Goldberg laboratory has demonstrated that the Shigella protein IcsA is sufficient to mediate this process. IcsA utilizes the cellular Cdc42 signal transduction pathway for actin assembly, which has been shown to be important in filopodia formation. This cellular pathway involves Cdc42 activation of members of the Wiskott-Aldrich syndrome protein (WASP) family. Activated WASP family members activate the Arp213 complex to nucleate actin and polymerize new filaments, which Arp2/3 cross-links at 700 angles to pre-existing filaments. IcsA is known to bind N-WASP, a member of the WASP family, yet the mechanism by which it activates N-WASP is unknown. IcsA is essential to Shigella virulence. We propose to characterize the mechanism of lcsA activation of N-WASP. We will identify residues of N-WASP and lcsA that are important to either lcsA binding or lcsA activation of N-WASP. We will then test whether N-WASP is activated by lcsA in a fashion similar to its activation by Cdc42. These studies will provide insight into both the molecular mechanisms of Shigella pathogenesis and the molecular mechanisms of 0dc42-mediated actin assembly.