ACTIN BASED MOTILITY OF A BACTERIAL PARASITE

单核细胞增多性李斯特菌是一种普遍存在的细菌，可引起严重的 孕妇、新生儿和免疫功能受损的食源性感染 成年人。细菌直接生长在受感染宿主的细胞质中。 细胞，并使用表单在受感染的细胞之间快速移动 基于肌动蛋白的运动性。这项提案的总体目标是 了解单核细胞增多性李斯特氏菌基于肌动蛋白的运动机制。 将使用生化和遗传筛查来确定Acta是否 蛋白质是一种细菌基因产物，是毒力和运动性所必需的 足以调节宿主细胞肌动蛋白细丝和宿主细胞之间的相互作用 细胞内的细菌或是否需要其他细菌蛋白。 互补性研究将确定宿主蛋白是 细菌的运动性，特别关注结合在一起的宿主蛋白 细菌Acta蛋白。免疫荧光和视频显微镜 这些技术将被用来解决这样一个问题，即极性如何 细菌的运动是建立和维持的。最后，一个光学的 力陷阱(激光镊子)将被用来测量力的大小 由受感染细胞中的细菌移动和无细胞提取物产生 试图确定单核细胞增多性李斯特氏菌所需的力量 运动是由运动蛋白或肌动蛋白聚合提供的。 成功完成我们的研究目标不仅会给我们带来洞察力 防止细菌寄生虫传播的方法，如L. 单核细胞增多症，但也有助于我们理解广泛的 涉及基于肌动蛋白的细胞运动的各种基本生物学过程， 包括伤口愈合、免疫系统反应和胚胎 发展。此外，由于大多数肿瘤在死亡之前不是致命的 癌细胞离开肿瘤部位并侵入其他组织， 详细了解基于肌动蛋白的调节的基本机制 运动性也可能在治疗的发展中发挥重要作用 抗击癌症扩散的战略。

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.