Type III effector regulation of host signal transduction systems

项目摘要 细菌3型分泌系统(T3SS)“效应器”蛋白是引导 多种革兰氏阴性细菌传染病的进展。最近的研究估计， 单个病原体可将多达250种独特的效应蛋白直接送入宿主细胞。总而言之，这些 毒力因子抑制宿主的先天免疫反应，促进细菌的复制、传播 和疾病的进展。因此，确定细菌效应蛋白如何控制宿主细胞内 在结构、生化和细胞水平上的沟通途径是感染性疾病的持续挑战。 疾病研究。这项建议旨在揭示对这些宿主的结构和功能的理解- 病原体之间的关系。在这项提议之前，我们鉴定了一类细菌E3-泛素连接酶，它 保护人类病原体福氏志贺氏菌不受天然免疫系统的激活和执行 细菌裂解。在这里，我们将专门研究细菌调控的分子机制。 新发现的哺乳动物毛孔形成细胞溶血素家族。这包括确定如何 Gasdermins在分子和细胞水平上发挥抑制福氏志贺菌的作用(目标1)。我们还将 通过求解效应器-Gasdermin结构在原子水平上研究这种宿主-病原体的相互作用 使用X射线结晶学(目标2)。由此产生的基于结构的理论将在小鼠模型中进行测试 Gasdermin功能，旨在评估黏膜对广谱 肠道病原体(目标3)。开发针对细菌效应器-宿主酶复合体的新药将 成为抗击新出现的传染病的创新方法。虽然这一想法具有巨大的潜力，但 到目前为止，从毒力因子结构/功能研究中收集到的机械性信息的缺乏一直阻碍着 他们的发展成为合适的药物靶点。作为实现这一目标的手段，这些研究将使我们能够预测新的 未被充分研究的志贺氏菌效应蛋白的作用机制，并提供了对结构- 基于相关病原体群体的进化进程。

Project Summary Bacterial Type 3 Secretion System (T3SS) “effector” proteins are the primary virulence factors that guide the progression of numerous Gram-negative bacterial infectious diseases. Recent studies have estimated that a single pathogen delivers up to 250 unique effector proteins directly into host cells. Collectively, these virulence factors suppress host innate immune responses and facilitate bacterial replication, dissemination, and disease progression. Therefore, determining how bacterial effector proteins control host intracellular communication pathways at the structural, biochemical, and cellular level is an ongoing challenge in infectious disease research. This proposal seeks to reveal a structural and functional understanding of these host- pathogen relationships. Prior to this proposal, we identified a class of bacterial E3-ubiquitin ligases that protects the human pathogen Shigella flexneri from the innate immune system activation and execution of bacterial lysis. Here, we will specifically examine the molecular mechanism for bacterial regulation of the newly identified Gasdermin-family of mammalian pore forming cytolysins. This includes determining how Gasdermins function to suppress Shigella flexneri at the molecular and cellular level (Aim 1). We will also examine this host-pathogen interaction at atomic level resolution by solving the effector-Gasdermin structure using X-ray crystallography (Aim 2). The resulting structure-based theories will be tested in murine models of Gasdermin function that are designed to evaluate mucosal immune protection against a broad spectrum of enteric pathogens (Aim 3). Developing new drugs that target bacterial effector – host enzyme complexes would be an innovative approach to combat emerging infectious disease. While this idea holds great potential, the paucity of mechanistic information gleaned from virulence factor structure/function studies has so far hampered their development as suitable drug targets. As a means to this end, these studies will allow us to predict new mechanisms of action for understudied Shigella effector proteins, and provide a glimpse into the structural- based evolutionary progression of a related pathogen groups.