Listeria monocytogenes physiology and host pathogen interactions

摘要 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。 生病了。鉴于其良好的感染周期和遗传适应性，单核细胞增多性乳杆菌提供了一种 细胞内细菌致病机制和宿主免疫基本方面的有力工具 对细胞内病原体入侵的反应。进入宿主细胞胞浆分泌的单核细胞增多性乳杆菌 第二信使信使核苷酸c-di-AMP导致宿主细胞的先天免疫激活。我们 最近发现宿主蛋白Recon是这一反应的关键介质。Recon是一种酶，它的 C-二-AMP可抑制其活性。C-di-AMP抑制Recon导致ROS副产物积累 4-羟基-2-壬烯醛(4-HNE)，可增强核因子-kB的激活，导致一氧化氮合酶升高 在感染过程中表达和NO产生。有趣的是，我们发现宿主细胞产生的NO 促进单核细胞增多性乳杆菌的胞内运动，而不是限制细菌的生长。 单核细胞增多症表现出极无耐药性。此外，初步研究表明，4-HNE是 在接触细菌后由真核细胞普遍诱导，这种反应醛表现出 对细菌的抑菌作用类似于NO。此外，单核细胞增多性李斯特菌表现出极强的抗药性。 对4-HNE的抗菌作用，并诱导对4-HNE的特异性转录反应，这 我们假设能促进受感染宿主的存活。我们已经开始了体外生物化学研究，体内 未来的遗传学研究，以及小鼠感染模型，以询问L. 单核细胞增多症抵消了NO和4-HNE的抗菌作用，并利用NO来促进毒力。在……里面 目的一、我们将询问单核细胞增多性李斯特氏菌用于解毒和中和抗菌剂的机制。 4-HNE的作用。在AIM II中，我们建议详细说明NO耐药的分子机制及其影响 关于细菌的毒性。最后，在目标III中，我们将详细介绍一氧化氮诱导的单核细胞增多性乳杆菌肌动蛋白的机制。 基于运动性，并探索这一过程对细菌入侵和传播的体内影响。同舟共济 这些研究将确定精致的抗微生物先天免疫反应的分子机制 被单核细胞增多性乳杆菌用来促进真核宿主内的存活。 。

ABSTRACT 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. L. monocytogenes that enter into the host cell cytosol secrete the second messenger signaling nucleotide, c-di-AMP, resulting in innate immune activation by the host cell. We recently identified the host protein RECON as a key mediator of this response. RECON is an enzyme whose activity is inhibited by c-di-AMP. C-di-AMP inhibition of RECON results in the accumulation of the ROS byproduct 4-hydroxy-2-nonenal (4-HNE), which augments NF-kB activation, resulting in elevated nitric oxide synthase expression and NO production during infection. Intriguingly, we have revealed that NO produced by the host cell promotes L. monocytogenes intracellular motility, rather than restricting bacterial growth, and that L. monocytogenes exhibits extreme NO resistance. Additionally, preliminary studies have revealed that 4-HNE is ubiquitously induced by eukaryotic cells following exposure to bacteria and that this reactive aldehyde exhibits antimicrobial effects on bacteria analogous to NO. Furthermore, L. monocytogenes exhibits extreme resistance to the antimicrobial effects of 4-HNE and induces a specific transcriptional response to 4-HNE exposure, which we hypothesize promotes survival within the infected host. We have begun in vitro biochemical studies, in vivo forward genetic studies, and the murine models of infection to interrogate the mechanisms by which L. monocytogenes counteracts the antimicrobial effects of NO and 4-HNE and utilizes NO to promote virulence. In Aim I, we will interrogate the mechanisms used by L. monocytogenes to detoxify and counteract the antimicrobial effects of 4-HNE. In Aim II, we propose to detail the molecular mechanisms of NO resistance and the impacts on bacterial virulence. Finally, in Aim III we will detail the mechanism of NO induced L. monocytogenes actin- based motility and explore the in vivo impacts of this process on bacterial invasion and dissemination. Together these studies will define the molecular mechanisms of exquisite antimicrobial innate immune responses employed by L. monocytogenes to promote survival within the eukaryotic host. .