Actin-Cytoskeleton Rearrangements by Salmonella

尽管公共卫生有所改善，但沙门氏菌病每年仍使世界经济损失数十亿美元，并且仍然是报告的食源性疾病的头号原因。 沙门氏菌感染涉及细菌和宿主细胞之间复杂和高度协调的相互作用。沙门氏菌通过细菌III型分泌系统将蛋白质注入宿主细胞。 我们的工作假设是，这些细菌蛋白质从事宿主蛋白质的肌动蛋白聚合以及解聚，这两个过程所需的沙门氏菌诱导的肌动蛋白细胞骨架重排和非吞噬细胞的细菌入侵。 本项目的目标是通过使用微生物、生物化学和细胞方法来鉴定和表征在体外和体内调节肌动蛋白动力学中发挥作用的细菌和宿主蛋白。 该建议的重点是沙门氏菌诱导的肌动蛋白重排涉及SiPA的分子机制。 我们已经表明，SiPA结合肌动蛋白和调节肌动蛋白动力学，通过降低肌动蛋白聚合的临界浓度和抑制肌动蛋白丝解聚。 我们还表明，SiPA增加了T-质体的成束活性，从而增加了肌动蛋白束的稳定性。 初步结果表明，其他宿主蛋白存在于SiPA-肌动蛋白复合物和SiPA活动必须关闭其他细菌或宿主因素。我们建议研究沙门氏菌诱导的肌动蛋白细胞骨架重排是如何启动，维持和随后逆转的。 我们已经开发了必要的检测和试剂，以检查肌动蛋白的结构和调查的作用SiPA和宿主蛋白在调节沙门氏菌诱导的肌动蛋白细胞骨架重排。 这项研究的结果将有助于我们了解沙门氏菌如何拦截正常细胞成分来调节宿主肌动蛋白细胞骨架。 更好地了解这些过程将有助于开发新的化疗药物用于治疗和预防沙门氏菌病。 这些实验还将为基本宿主细胞功能提供新的见解，包括细胞骨架重排和细胞运动。

Despite improvements in public hygiene, salmonellosis continues to cost the world economy billions of dollars each year and remains to be the number one cause of reported foodborne diseases. The Salmonella infection involves complex and highly orchestrated interactions between the bacterium and host cells. Salmonella injects proteins into host cells via a bacterial type III secretion system. Our working hypothesis is that these bacterial proteins engage host proteins for actin polymerization as well as depolymerization, two processes that are required for Salmonella-induced actin cytoskeleton rearrangements and invasion of non-phagocytic cells by the bacterium. The goal of this project is to identify and characterize bacterial and host proteins that play a role(s) in modulating actin dynamics both in vitro and in vivo by using microbiological, biochemical and cellular approaches. This proposal focuses on the molecular mechanism of Salmonella-induced actin rearrangements involving SipA. We have shown that SipA binds actin and modulates actin dynamics by decreasing the critical concentration for actin polymerization and by inhibiting depolymerization of actin filaments. We also showed that SipA increases the bundling activity of T-plastin, which increases the stability of actin bundles. Preliminary results indicate that additional host proteins are present in the SipA-actin complex and SipA activities must be turned off by other bacterial or host factors. We propose to investigate how Salmonella-induced actin cytoskeleton rearrangements are initiated, maintained and subsequently reversed. We have developed assays and reagents necessary to examine the actin architecture and investigate roles of SipA and host proteins in modulating Salmonella-induced actin cytoskeleton rearrangements. Results from this study will help us understand how Salmonella intercepts normal cellular constituents to modulate host actin cytoskeleton. A better understanding of these processes will facilitate the development of new chemotherapeutic agents for the treatment and prevention of salmonellosis. These experiments will also provide new insights into basic host cellular functions, including cytoskeletal rearrangements and cell movement.