Brucella Stationary Phase Gene Expression and Virulence

Hfq是一种RNA结合蛋白，在基因转录后调控中发挥多种作用， 在细菌中表达。在所讨论的基因是转录调节子的情况下，存在或不存在转录调节子。 Hfq的缺乏也可以影响由其控制的基因子集的表达模式。 调节器我们实验室以前的研究表明，Hfq是野生型毒力所必需的。 小鼠模型中的流产布鲁氏菌2308。到目前为止，我们已经确定了超过40个基因，需要Hfq的， 在该菌株中的野生型表达，其中七种（sodC、ahpCD、virB、bvrRS、omp 25、cydAB和znuA） 对小鼠的毒性是必需的！RT-PCR分析表明，sodC、ahpCD、virB和cydAB显示了与pCD 3和pCD 4的同源性。 在6.流产2308，而bvrRS 在所有已检测的实验条件下，转录似乎是Hfq依赖性的。 这些实验结果表明，转录激活因子或替代性CT因子作为一种转录调节因子， 在B中Hfq和sodC、bvrRS、virB和cydAB野生型表达之间的中间调节连接。 流产2308.我们对B.然而，流产替代因子A无效突变体表明， 另一个因素并没有起到这个作用。因此，为了更好地了解 Hfq与B中的sodC、ahpCD、virB、bvrRS和cydAB之间的调节联系。流产2308，特异性 本申请中概述的研究的目的是a）检验转录激活因子是 负责该菌株中sodC、ahpCD、bvrRS、virB和cydAB的Hfq依赖性表达; B） 鉴定这种Hfq依赖性转录调节因子（HtcR）;和c）确定HtcR- sodC、ahpCD、bvrRS、virB和cydAB的依赖性启动子区是B的毒力所必需的。 小鼠流产2308。从拟议的研究中获得的信息将有助于深入了解 布鲁氏菌在哺乳动物体内驻留期间调节其基因表达的机制 这些信息应该有助于设计新的候选疫苗，并改善 化疗方法。这些研究还可能确定一种新的机制， 基因在原核生物中的表达。布鲁氏杆菌属不具有替代物a的同系物 在许多革兰氏阴性菌中执行此功能的因子RpoS，但Hfq似乎是 socfC、ahpCD、virB和cydAB在B中的高效稳定期表达。流产2308.

Hfq is an RNA binding protein that plays multiple roles in the post-transcriptional regulation of gene expression in bacteria. In cases where the gene in question is a transcriptional regulator, the presence or absence of Hfq can also influence the expression patterns of the subsets of genes controlled by this regulator. Previous studies in our laboratory have shown that Hfq is required for the wild-type virulence of Brucella abortus 2308 in the mouse model. To date, we have identified > 40 genes that require Hfq for their wild-type expression in this strain, and seven of these (sodC, ahpCD, virB, bvrRS, omp25, cydAB and znuA) are necessary for virulence in mice! RT-PCR analysis indicates that sodC, ahpCD, virB.and cydAB display both Hfq-dependent and Hfq-independent patterns of transcription in 6. abortus 2308, while bvrRS transcription appears to be Hfq-dependent under all experimental conditions that have been examined. These experimental findings suggest that a transcriptional activator or alternativeCTfactor serves as an intermediate regulatory link between Hfq and wild-type expression of sodC, bvrRS, virB and cydAB in B. abortus 2308. Our phenotypic analyses of B. abortus alternative factor a null mutants, however, suggest that an alternative a factor is not playing this role. Consequently, in order to gain a better understanding of the regulatory link between Hfq and sodC, ahpCD, virB, bvrRS, and cydAB in B. abortus 2308, the specific aims of the studies outlined in this application are a) to test the hypothesis that a transcriptional activator is responsible for Hfq-dependent expression of sodC, ahpCD, bvrRS, virB and cydAB in this strain; b) to identify this Hfq-dependent transcriptional regulator (HtcR); and c) to determine the extent to which the HtcR- dependent promoter regions of sodC, ahpCD, bvrRS, virB and cydAB are required for the virulence of B. abortus 2308 in mice. Information derived from the proposed studies will provide insight into the mechanisms by which the brucellae regulate their gene expression during residence in their mammalian hosts, and such information should be useful for the design of novel vaccine candidates and improved chemotherapeutic approaches. These studies may also identify a novel mechanism for regulating stationary phase gene expression in prokaryotes. The Brucella spp. do not possess a homolog of the alternative a factor RpoS which performs this function in many Gram-negative bacteria, but Hfq appears to be required for the efficient stationary phase expression of socfC, ahpCD, virB and cydAB in B. abortus 2308.