ACTIN BASED MOTILITY OF A BACTERIAL PARASITE

单核细胞增生李斯特菌是一种普遍存在的细菌， 孕妇、新生儿和免疫功能低下者的食物传播感染 成年人了该细菌直接在受感染宿主的细胞质中生长 细胞，并使用一种形式在感染的细胞中和细胞之间快速移动， 基于肌动蛋白的运动本提案的总体目标是 了解L.单核细胞增多症 生物化学和遗传筛选将用于确定ActA是否 蛋白质是一种细菌基因产物，对毒力和运动性是必需的， 足以介导宿主细胞肌动蛋白丝和 细胞内细菌或是否需要其他细菌蛋白质。 补充研究将确定宿主蛋白质是必要的， 细菌运动性，特别关注与细菌结合的宿主蛋白质， 细菌ActA蛋白。免疫荧光和视频显微镜 技术将被用来解决如何极性的问题， 建立并维持细菌运动。最后，光学 力阱（激光镊子）将用于测量力的大小 通过移动感染细胞中的细菌和无细胞提取物产生， 试图确定L.单核 运动由马达蛋白或肌动蛋白聚合提供。 成功完成我们的研究目标不仅会让我们 防止细菌寄生虫如L. 单核细胞增多症，但也有助于我们了解广泛的 各种基本的生物过程，包括肌动蛋白为基础的细胞运动， 包括伤口愈合、免疫系统反应和胚胎发育。 发展此外，由于大多数肿瘤在肿瘤发生之前并不致命， 癌细胞从肿瘤部位转移并侵入其他组织， 详细了解调节肌动蛋白的基本机制 运动性也可能是重要的治疗发展， 对抗癌症扩散的策略。

Listeria monocytogenes is a ubiquitous bacterium that can cause serious food-borne infections in pregnant women, newborns and immunocompromised adults. The bacterium grows directly in the cytoplasm of infected host cells and moves rapidly throughout and between infected cells using a form of actin-based motility. The overall goal of this proposal is to understand the mechanism of the actin-based motility of L. monocytogenes. Biochemical and genetic screens will be used to determine whether the ActA protein, a bacterial gene product necessary for virulence and motility, is sufficient to mediate interactions between host cell actin filaments and intracellular bacteria or whether other bacterial proteins are required. Complementary studies will identify host proteins that are necessary for bacterial motility, focusing in particular on host proteins that bind to the bacterial ActA protein. Immunofluorescence and video microscopy techniques will be used to address the question of how the polarity of bacterial movement is established and maintained. Finally, an optical force trap (laser tweezers) will be used to measure the amount of force generated by moving bacteria in infected cells and cell-free extracts in an attempt to determine whether the force necessary for L. monocytogenes movement is provided by a motor protein or by actin polymerization. Successful completion of our research goals would not only give insight into ways of preventing the spread of bacterial parasites such as L. monocytogenes but would also contribute to our understanding of a wide variety of basic biological processes involving actin-based cell movement, including wound healing, immune system responses, and embryonic development. Furthermore, since most tumors are not lethal until the cancer cells move away from the tumor site and invade other tissues, a detailed understanding of the basic mechanisms that regulate actin-based motility may also be important in the development of therapeutic strategies for combating the spread of cancer.