Role of Yersinia pestis Ail in Yop delivery and plague

描述（由申请人提供）：革兰氏阴性菌的高效三型分泌（T3S）需要粘附在目标宿主细胞上。我们最近确定鼠疫耶尔森氏菌粘附素Ail通过与宿主纤维连接蛋白结合促进耶尔森氏菌外蛋白（Yops）的T3S。鼠疫感染需要传递Yops，缺乏Yops的突变体是完全无毒的。一个吗?ail突变体在体外的Yop递送较差，在体内的LD50降低（LD50增加3000倍）。因此，Ail似乎是Yop在体内传递的重要粘附素。这使得all成为鼠疫杆菌疫苗开发和抗鼠疫治疗的重要潜在靶点。我们假设Ail结合纤维连接蛋白与宿主细胞相互作用，可能通过刺激Yop传递所需的受体启动的细胞信号传导来实现Yop的有效传递。我们进一步假设Fn在表达ail的细菌和宿主细胞（Fn受体）上的21种整合素之间起桥梁作用。？整合素信号最近被证明在密切相关的病原体假结核杆菌侵袭介导的Yop传递中起重要作用。在本提案中，我们将定义Ail与Fn相互作用的区域，并解决Ail与Fn结合以及随后的？1整合蛋白。通过了解鼠疫杆菌的关键黏附素在Yop递送过程中的关键步骤，我们将大大扩展我们对黏附在Yop递送过程中的作用的认识，特别是T3S。这些研究将广泛适用于其他利用T3S机制传递毒素的细菌病原体。此外，通过确定鼠疫杆菌与宿主细胞之间的关键相互作用机制，我们可以确定可用于治疗鼠疫的治疗靶点，鼠疫是一种快速致命的疾病和生物恐怖主义威胁。

DESCRIPTION (provided by applicant): Efficient Type Three Secretion (T3S) by Gram-negative bacteria requires adhesion to the targeted host cell. We have recently determined that the Yersinia pestis adhesin Ail facilitates T3S of Yersinia outer proteins (Yops) via binding to host fibronectin. Yop delivery is required for plague infection and mutants that lack Yops are completely avirulent. A ?ail mutant has poor Yop delivery in vitro and is attenuated in vivo (>3000-fold increase in LD50). Thus, Ail appears to be a prominent adhesin for Yop delivery in vivo. This makes Ail an important potential target for Y. pestis vaccine development and anti-plague therapies. We hypothesize that Ail in conjunction with fibronectin interacts with host cells to allow efficient Yop delivery, possibly by stimulating receptor-initiated cell signaling required for Yop delivery. We further hypothesize that Fn acts as a bridge between Ail-expressing bacteria and 21 integrins on host cells (receptors for Fn). ?1 integrin signaling has recently been shown to be important for invasin-mediated Yop delivery by the closely related pathogen, Y. pseudotuberculosis. In this proposal, we will define the regions of Ail that interact with Fn and address the effects of Ail binding to Fn and subsequent engagement of ?1 integrins. By understanding this critical step in the Yop delivery process by a key adhesin of Y. pestis, we will significantly expand our knowledge of the role of adhesion in Yop delivery in particular and T3S in general. These studies will be broadly applicable to other bacterial pathogens that utilize a T3S mechanism for toxin delivery. Furthermore by defining a crucial interaction mechanism between Y. pestis and host cells, we may identify targets for therapeutics that can be used to treat plague, a rapidly fatal disease and bioterrorism threat. The Aims of this proposal are: Aim 1: Determine the residues of Ail required for host cell binding and Yop delivery Aim 2: Characterize Ail binding to host cell fibronectin and the role of 21 integrins in Ail-mediated Yop delivery PUBLIC HEALTH RELEVANCE: Yersinia pestis causes the rapidly fatal infectious disease plague, making Y. pestis a bioterrorism threat. This project is aimed at furthering our understanding of the interaction of the Y. pestis surface protein Ail with host cells. This critical interaction is required for plague virulence and characterizing this interaction may lead to development of anti-plague therapeutics and/or an effective plague vaccine.