Coordination of metabolism and virulence during infection

描述（由申请人提供）：沙门氏菌感染是发达国家和发展中国家发病率和死亡率的重要原因。沙门氏菌有2600多种血清型，表现出各种宿主范围和疾病表现，包括胃肠炎、菌血症、转移性感染以及副伤寒和伤寒。在所有情况下，感染都需要细菌适应许多宿主室的不同条件，这在很大程度上是由毒力和代谢基因表达的变化介导的。了解感染周期中的这些适应对于制定预防和治疗感染的新策略非常重要。尽管知识有限，但这种生物的毒力和代谢基因的调控通过涉及SirA（沙门氏菌入侵调节因子）和CsrA（碳储存调节因子）的遗传回路错综复杂地联系在一起。SirA是一种DNA结合转录因子，是BarA-SirA双组分信号转导系统的应答调节因子。CsrA是一种调节mRNA翻译和稳定性的RNA结合蛋白。CsrA的活性受小的非编码rna （CsrB，证监会）调控，后者将CsrA蛋白隔离。反过来，csrB和证监会的转录被SirA激活。该系统的调节对宿主室内不同的碳代谢底物和最终产物作出反应，这导致了碳可用性在很大程度上控制感染周期中的适应性转变的假设。在Aim 1中，将使用基因组学、生物信息学、分子遗传学和生化方法的结合来定义SirA和CsrA的调控，从而大大增加我们对代谢和毒力之间调控联系的理解。在目标2中，将使用几种互补的方法来精确确定该系统基因在沙门氏菌感染小鼠期间的表达和活性的时间和位置。这些信息将在法规（在Aim 1中定义）以及已知在体外影响这些法规的环境和代谢条件的背景下进行评估。SirA和CsrA同源基因在整个γ -变形菌群中高度保守，对研究过的每个物种的疾病传播和/或毒力都很重要。因此，了解影响SirA和CsrA活性的条件和刺激，以及这些蛋白质协调毒力和代谢基因表达的机制，可能适用于广泛的病原体。

DESCRIPTION (provided by applicant): Salmonella infections are a significant cause of morbidity and mortality in both developed and developing nations. There are over 2600 serovars of Salmonella that exhibit a variety of host ranges and disease manifestations, which include gastroenteritis, bacteremia, metastatic infections and paratyphoid and typhoid fevers. In all cases, infection requires adaptation of the bacterium to distinct conditions of a number of host compartments, mediated in large part by changes in the expression of virulence and metabolism genes. Understanding these adaptations during the infection cycle is important for developing new strategies for preventing and treating infection. Although knowledge is limited, regulation of the virulence and metabolism genes of this organism are intricately linked through genetic circuitry involving SirA (Salmonella invasion regulator) and CsrA (carbon storage regulator). SirA is a DNA binding transcription factor that is the response regulator of the BarA-SirA two component signal transduction system. CsrA is an RNA binding protein that regulates mRNA translation and stability. CsrA activity is regulated by small noncoding RNAs (CsrB, CsrC), which sequester the CsrA protein. In turn, the transcription of csrB and csrC is activated by SirA. Regulation by this system responds to substrates and end products of carbon metabolism, which vary within host compartments, leading to the hypothesis that the status of carbon availability in large part governs adaptive transitions during the infection cycle. In Aim 1, a combination of genomic, bioinformatic, molecular genetic and biochemical approaches will be used to define the SirA and CsrA regulons, and thereby greatly increase our understanding of the regulatory links between metabolism and virulence. In Aim 2, several complementary approaches will be used to determine precisely when and where genes of this system are expressed and active during Salmonella infection of mice. This information will be evaluated in context with the regulons (defined in Aim 1) as well as the environmental and metabolic conditions that are known to influence these regulators in vitro. SirA and CsrA orthologs are highly conserved throughout the gamma-proteobacteria and are important for disease transmission and/or virulence in every species in which they have been examined. Thus, an understanding of the conditions and stimuli affecting SirA and CsrA activities and the mechanisms by which these proteins coordinate virulence and metabolic gene expression may be applicable to a broad range of pathogens.