The role of redox sensing in Listeria monocytogenes pathogenesis

项目总结 细胞内病原体在世界范围内造成了相当大的发病率和死亡率。在这里， 模型细胞内兼性致病菌单核细胞增生性李斯特氏菌(Lm)将被用来研究细菌 病原体识别并适应宿主环境。以前的研究提出了一种模型，在这种模型中，特定的 氧化还原环境的改变是细胞内病原体检测到的生物线索之一 感染作为一种机制来感知它们的定位并相应地调节基因。具体地说，我们发现 氧化还原反应转录调节子SpxA1是体外有氧生长所必需的，也是LM的关键 致命性。初步数据显示，SpxA1在体外和体内调节数百个基因。这些结果 已经为研究每一种不同生长所需的特定基因奠定了基础 环境。 Aim 1a中提出的实验将确定在体外培养LM有氧生长所需的基因， 而Aim 1b和1c将定义致病所需的SpxA1依赖基因。所描述的实验 在AIM 2中，将开发用于监控SpxA1活性的报告菌株，并将应用这些菌株来定义 宿主信号在体内激活SpxA1。职业病原体，如LM，已经进化成抵抗或逃避 针对入侵病原体的宿主衍生的抗微生物因子。我们将使用SpxA1介导的转录 适应作为研究这些宿主防御的灵敏读数。这些研究的结果将 确定感染过程中遇到的宿主细胞应激源和相应的LM转录 致病所需的反应。透彻地了解以下信令级联 在感染过程中被激活，以及刺激这些途径的宿主提示可能揭示出 细胞内细菌病原体进化到检测到的宿主胞浆。

PROJECT SUMMARY Intracellular pathogens account for a significant amount of morbidity and mortality world-wide. Here, the model facultative intracellular pathogen Listeria monocytogenes (Lm) will be used to investigate how bacterial pathogens recognize and adapt to the host environment. Previous studies suggested a model in which specific alterations in the redox environment are one of the biological cues detected by intracellular pathogens during infection as a mechanism to sense their localization and regulate genes accordingly. Specifically, we identified the redox-responsive transcriptional regulator SpxA1 as essential for aerobic growth in vitro and critical for Lm virulence. Preliminary data revealed that SpxA1 regulates hundreds of genes in vitro and in vivo. These results have set the stage for investigations into the specific genes that are required in each distinct growth environment. Experiments proposed in Aim 1a will identify the genes that are required for Lm aerobic growth in vitro, while Aim 1b and 1c will define the SpxA1-dependent genes required for pathogenesis. Experiments described in Aim 2 will develop reporter strains with which to monitor SpxA1 activity and will apply these to define the host signals that activate SpxA1 in vivo. Professional pathogens, such as Lm, have evolved to resist or evade host-derived antimicrobial factors that target invading pathogens. We will use SpxA1-mediated transcriptional adaptation as a sensitive readout with which to investigate these host defenses. Results from these studies will identify the host cell stressors that are encountered during infection and the corresponding Lm transcriptional response that is required for pathogenesis. A thorough understanding of the signaling cascades that are activated during infection and the host cues that stimulate these pathways may reveal fundamental features of the host cytosol that intracellular bacterial pathogens have evolved to detect.