Brucella Stationary Phase Gene Expression and Virulence

描述（由申请方提供）：编码固定相特异性替代c因子RpoS的mRNA的最佳翻译所需的大肠杆菌和沙门氏菌RNA结合蛋白的宿主因子（HF-I）蛋白。hfq基因编码HF-I，E. coil和S.鼠伤寒hfq突变体表现出与大肠杆菌基本相同的广义静止期缺陷型。coil和S.鼠伤寒rpoS突变体。我们实验室以前的研究表明，B。流产hfq突变体Hfq 3在体外显示出普遍的稳定期缺陷，但更重要的是，突变研究已经清楚地确定HF-1是B的野生型毒力所必需的。流产2308小鼠模型。在由NIAID资助的研究中，我们已经在B中确定了18个遗传位点。2308，其中6个是小鼠中野生型毒力所必需的。三个（ahpCD，sodC和cydAB）编码稳定相抗氧化剂，保护细胞内的布鲁氏菌在吞噬体室的氧化损伤。有趣的是，virB操纵子（编码IV型分泌系统）和bvrRS双组分调节系统（调节参与维持细胞包膜完整性的基因）也需要HF-I才能在B中正常表达。流产2308.布鲁氏杆菌属缺乏典型的RpoS同源物，因此HF-1和稳定期基因表达之间的调控联系的性质尚不清楚。因此，本竞争性续期申请中描述的项目目标是：a）调查B的个人贡献。牛胎HF-I调节基因dps、cfa、znuA、oppD和bolA至体外稳定期生理学和小鼠中的毒力; B）更好地确定HF-I在调节virB和bvrRS操纵子中的作用，和c）检验替代因子RpoE 2将HF-I和B中的稳定期基因表达联系起来的假设。abortus 2308，因此在该细菌中充当“功能性RpoS同源物”。定义HF-I介导的稳定期基因表达的基础，并阐明个别稳定期基因产物在宿主巨噬细胞中成功存活和复制的贡献，将为我们提供重要的基础信息，这将有助于设计新的候选疫苗和改进的化疗方法。

DESCRIPTION (provided by applicant): The host factor (HF-I) proteins of Escherichia coil and Salmonella RNA binding proteins that are required for optimal translation of the mRNA encoding the stationary phase specific alternative c factor RpoS. The hfq gene encodes HF-I, and E. coil and S. typhimurium hfq mutants display essentially the same generalized stationary phase defective phenotype as E. coil and S. typhimurium rpoS mutants. Previous studies in our laboratory have shown that the B. abortus hfq mutant Hfq3 displays a generalized stationary phase defect in vitro, but more importantly, mutational studies have clearly established that HF-I is required for the wild-type virulence of B. abortus 2308 in the mouse model. In studies funded by our current award from NIAID, we have identified 18 genetic loci in B. abortus 2308 that are regulated by HF-I, 6 of which are required for wild-type virulence in mice. Three (ahpCD, sodC and cydAB) encode stationary phase antioxidants that protect the intracellular brucellae from oxidative damage in the phagosomal compartment. Interestingly, the virB operon (which encodes the Type IV secretion system) and the bvrRS two-component regulatory system (which regulates genes involved in maintaining cell envelope integrity) also require HF-I for normal expression in B. abortus 2308. The Brucella spp. lack a typical RpoS homolog, so the nature of the regulatory link between HF-I and stationary phase gene expression in not yet clear. Consequently, the objectives of the project described in this competing renewal application are a) to investigate the individual contributions of the B. abortus HF-I regulated genes dps, cfa, znuA, oppD, and bolA to stationary phase physiology in vitro and virulence in mice; b) to better define the role of HF-I in the regulation of the virB and bvrRS operons, and c) to test the hypothesis that the alternative a factor RpoE2 links HF-I and stationary phase gene expression in B. abortus 2308, and thus serves as a "functional RpoS homolog in this bacterium. Defining the basis for HF-I mediated stationary phase gene expression in Brucella and elucidating the contributions of individual stationary phase gene products to successful survival and replication in host macrophages will provide us with important basic information that will be useful for the design of novel vaccine candidates and improved chemotherapeutic approaches.