Listeria monocytogenes physiology and host pathogen interactions

 描述(申请人提供)：单核细胞增多性李斯特菌是一种革兰氏阳性、机会性、胞内致病菌，可引起食源性疾病。单核细胞增多性乳杆菌具有良好的感染周期和遗传适应性，为研究细胞内细菌的致病机理和宿主对细胞内病原体入侵的免疫反应提供了有力的工具。先前已经证明，进入宿主细胞胞浆的单增李斯特氏菌分泌一种信号核苷酸c-di-AMP，从而刺激宿主产生干扰素。我们的初步研究发现，c-di-AMP信号在细菌在肉汤和宿主内生长的能力中发挥着重要作用。此外，有证据表明，c-di-AMP可能具有感染宿主细胞诱导的干扰素以外的功能后果。利用蛋白质组学和遗传学研究，我们已经确定了新的细菌和宿主途径，这些途径可能介导与这种独特的细菌信号分子相关的多种表型。在目标I中，我们建议探索受c-di-AMP调控的细菌小RNA在李斯特菌毒力所需的作用。在AIM II中，我们将研究三种c-di-AMP结合蛋白在介导信号转导中的作用。在最终目标中，我们将表征c-di-AMP与一种新的宿主蛋白结合的影响，并阐明这些相互作用对感染结局的影响。总之，这些研究将确定c-di-AMP信号在这种细胞内细菌感染过程中介导宿主病原体相互作用的分子机制。

 DESCRIPTION (provided by applicant): Listeria monocytogenes is a gram-positive, opportunistic, intracellular bacterial pathogen that causes food borne illness. Given its well-characterized infection cycle and genetic amenability, L. monocytogenes provides a powerful tool to interrogate the fundamental aspects of intracellular bacterial pathogenesis and the host immune response to invasion by intracellular pathogens. It has previously been demonstrated that L. monocytogenes that enter into the host cell cytosol secrete a signaling nucleotide, c-di-AMP, resulting in stimulation of host IFN-ß production. Our preliminary studies have uncovered important roles for c-di-AMP signaling in the ability of the bacterium to grow in broth and within the host. Furthermore, evidence suggests c-di-AMP may have functional consequences beyond IFN-ß induction by the infected host cell. Using proteomics and genetic studies we have identified novel bacterial and host pathways that may mediate the numerous phenotypes associated with this unique bacterial signaling molecule. In Aim I, we propose to explore the role of a bacterial small RNA regulated by c-di-AMP and required for Listeria virulence. In Aim II, we will characterize the role of three c-di-AMP binding proteins in mediating signal transduction. In the final aim, we will characterize the effects of c-di-AMP binding to a novel host protein and elucidate the effects of these interactions on the outcome of infection. Together these studies will define the molecular mechanisms of c-di-AMP signaling that mediate host pathogen interactions during infection by this intracellular bacterium.