Brucella Stationary Phase Gene Expression and Virulence

描述(由申请人提供)：大肠杆菌的宿主因子(HF-I)蛋白和沙门氏菌RNA结合蛋白，是编码固定相特定的替代c因子rpos的mRNA的最佳翻译所需的。Hfq基因编码hf-I，突变株和鼠伤寒沙门氏菌hfq突变株表现出与螺旋杆菌和鼠伤寒沙门氏菌rpos突变株相同的普遍的静止相缺陷表型。我们实验室以前的研究表明，流产杆菌Hfq突变体Hfq3在体外表现出普遍的固定相缺陷，但更重要的是，突变研究清楚地证明，在小鼠模型中，流产杆菌野生型毒力需要Hf-I。在我们目前由NIAID资助的研究中，我们已经在流产杆菌2308中确定了18个受HF-I调控的遗传位点，其中6个是小鼠野生型毒力所必需的。三个(ahpCD、SODC和cydAB)编码固定相抗氧化剂，保护细胞内的布鲁氏菌免受吞噬体内的氧化损伤。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(调节与维持细胞包膜完整性有关的基因)也需要HF-I才能在流产杆菌2308中正常表达。布鲁氏菌属。缺乏典型的rpos同源基因，因此目前尚不清楚HF-I和稳定期基因表达调控的本质联系。因此，在这项竞争性更新申请中描述的项目的目标是：a)研究流产杆菌HF-I调控基因Dps、CFA、znuA、OPPD和BOLA对体外静止相生理学和小鼠毒力的单独贡献；b)更好地确定HF-I在调节VIRB和bvrRS操纵子中的作用；以及c)测试替代a因子RpoE2将流产杆菌中的HF-I和静止相基因表达联系起来，从而在该细菌中充当“功能Rpos同源基因”的假设。明确HF-I介导的布鲁氏菌稳定期基因表达的基础，阐明单个稳定期基因产物对宿主巨噬细胞成功存活和复制的贡献，将为设计新的候选疫苗和改进化疗方法提供重要的基础信息。

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.