Regulation of Francisella virulence by sRNAs

项目摘要 土拉热弗朗西丝菌（Francisella tularensis，Ft）是一种潜在的生物恐怖因子，兼性胞内病原菌，是引起 兔热病的病原体。根据其几个属性，Ft已被CDC命名为第1级代理。而 在过去的15年里，关于这种病原体的细胞生物学、其方法 毒力基因调控的机制仍不完全清楚。在通常充满敌意的环境中生存和发展 在环境中，细菌必须监测其周围环境，并调整其基因表达和生理机能。 相应地这对于在感染期间持续与宿主相互作用的病原菌尤其重要。 感染基因调控传统上是由蛋白质调控因子介导的，但Ft含有很少的蛋白质 调节因子，缺乏经典的双组分调节系统，但介导 复杂的宿主-病原体过程，如宿主接触后早期免疫反应的抑制， 从含弗朗西斯菌的液泡中逃逸到胞质溶胶中。数量有限的孤儿双组分 存在包括响应调节器PmrA的成员。PmrA是弗朗西斯菌致病的关键因子，因为它 已经证明调节Ft生物膜形成、巨噬细胞内存活和动物毒力。小 RNA（sRNA）也越来越多地与病原体毒力的调节有关，我们已经 鉴定了661个Ft sRNA，包括由PmrA调节的子集（n=81）。本研究的总体目标是 了解这种重要病原体毒力的转录/转录后控制。整体 目的是鉴定与细胞毒相关的sRNA（PmrA调节的以及差异表达的 在巨噬细胞中）。中心假设是Ft sRNAs受PmrA和巨噬细胞的影响， 环境调节毒性。我们的目标的实现将揭示Ft疫苗或Ft疫苗的新靶点。 来对抗这种危险的病原体

PROJECT SUMMARY Francisella tularensis (Ft) is a potential agent of bioterror, facultative intracellular pathogen and the causative agent of tularemia. Based on several of its attributes, Ft has been named by the CDC as a Tier 1 agent. While several advances have been made in the last ~15 years regarding the cell biology of this pathogen, its method of virulence gene regulation remains incompletely understood. To survive and thrive in often hostile environments, a bacterium has to monitor its surroundings and adjust its gene expression and physiology accordingly. This is especially important for pathogenic bacteria that continuously interact with the host during an infection. Gene regulation is traditionally mediated by protein regulatory factors, but Ft contains few protein regulatory factors and is devoid of classically arranged two-component regulatory systems, yet mediates complex host-pathogen processes such as suppression of the immune response early after host contact and escape from the Francisella-containing vacuole into the cytosol. A limited number of orphan two-component members exist including the response regulator PmrA. PmrA is a key factor in Francisella pathogenesis, as it has been demonstrated to regulate Ft biofilm formation, intramacrophage survival and animal virulence. Small RNAs (sRNAs) are also increasingly associated with the regulation of virulence in pathogens, and we have identified 661 Ft sRNAs, including the subset regulated by PmrA (n=81). The overall goal of this research is to understand the transcriptional/post-transcriptional control of virulence in this important pathogen. The overall objective is to identify virulence-associated sRNAs (PmrA-regulated as well as those differentially expressed in macrophages). The central hypothesis is that Ft sRNAs are influenced by PmrA and the macrophage environment to regulate virulence. The achievement of our goals will uncover new targets for Ft vaccines or for therapeutics to counteract this dangerous pathogen.