Regulation of Listeria virulence gene expression by glutathione and hydrogen sulf

描述（由申请人提供）：单核细胞增生李斯特菌是一种革兰氏阳性兼性胞内细菌，能够侵入多种宿主细胞类型并复制 在细胞质中。介导侵入、空泡逃逸和在宿主胞质溶胶中存活的蛋白质都由正调控因子PrfA转录控制。PrfA属于转录因子的cAMP受体蛋白（Crp）家族，其在结合小分子辅因子时被激活。迄今为止，尚未鉴定出PrfA的辅因子，尽管据信对宿主细胞胞质溶胶特异性的信号触发PrfA活化，导致毒力基因表达。我们进行了正向遗传筛选，以确定允许Lm识别其胞质定位和激活毒力基因转录的因子。我们的“细胞质传感”筛选非常成功，因为我们鉴定了许多在PrfA依赖性基因调控中具有严重缺陷的基因，但以前从未与毒力相关。选择两种转座子突变体用于进一步研究，并且每种转座子突变体在静脉内感染的小鼠的脾和肝的定殖中显示3- 5log缺陷。本申请中详述的实验旨在剖析这些突变如何调节李斯特菌中的毒力基因表达。

DESCRIPTION (provided by applicant): Listeria monocytogenes is a Gram positive facultative intracellular bacterium that is capable of invading a wide range of host cell types and replicating in the cytosol. Proteins which mediate invasion, vacuolar escape, and survival in the host cytosol are all transcriptionally controlled by the positive regulatory factor PrfA. PrfA belongs t the cAMP receptor protein (Crp) family of transcription factors, which are activated upon binding small molecule cofactors. To date, a cofactor has not been identified for PrfA, although it is believed that a signal(s) specific to the host cell cytosol triggers PrfA activation, leading to virulence gene expression. We performed a forward genetic screen to identify factors that allow Lm to recognize its cytosolic localization and activate transcription of virulence genes. Our screen for 'cytosol sensing' was extremely successful, as we identified many genes that have severe defects in PrfA-dependent gene regulation, but have never before been associated with virulence. Two transposon mutants were chosen for further investigation, and each displayed a 3-5 log defect in colonization of the spleens and livers of intravenously infected mice. Experiments detailed in this application aim to dissect how these mutations regulate virulence gene expression in Listeria.