Role of WhiB3 in M. tuberculosis virulence

描述(申请人提供)：结核分枝杆菌(结核分枝杆菌)是全球主要死亡原因之一，每年夺走数百万人的生命。全世界约有17亿人无症状地感染结核杆菌，构成了全球公共卫生控制措施的主要障碍。以前的工作已经表明，牛分枝杆菌的主要西格玛因子RpoV 4.2区域的一个点突变(Arg515-&gt；His)正在减弱。感染MtbwhiB3的小鼠的存活时间明显长于感染野生型Mtb的小鼠。此外，感染MtbwhiB3的小鼠的肺似乎受到的不利影响要小得多。最近的研究表明，WhiB3是一个4Fe-4S簇蛋白，启动代谢转换到体内首选的碳源--脂肪酸。我们假设WhiB3是一个细胞内的氧化还原感受器，维持氧化还原动态平衡。为了更好地了解这一生理事件的机制，我们将鉴定有效的铁-硫(Fe-S)重组所必需的WhiB3氨基酸，并使用电子顺磁共振波谱来表征这些突变的蛋白质。我们将使用全基因组表达谱来检测WhiB3在维持氧化还原动态平衡方面的贡献，并分析MtbwhiB3的代谢物图谱。这些研究将把WhiB3定性为干预措施的潜在目标，这些干预措施可能会消除毒力，但不会导致生长。这些研究还将为理解结核分枝杆菌如何破坏宿主免疫提供洞察力。

DESCRIPTION (provided by applicant): M. tuberculosis (Mtb) is one of the leading causes of death worldwide and claims millions of lives annually. Approximately ~1.7 billion people worldwide are asymptomatically infected with the tubercle bacillus and constitute a major impediment to worldwide public health control measures. Previous work had shown that a point mutation (Arg515->His) in the 4.2 domain of RpoV, the principal sigma factor in Mycobacterium bovis, is attenuating. Mice infected with MtbwhiB3 showed significantly longer survival times than mice infected with the wild type Mtb. In addition, the lungs of MtbwhiB3-infected mice appeared much less adversely affected. Recent studies have shown that WhiB3 is a 4Fe-4S cluster protein and initiates the metabolic switchover to the preferred in vivo carbon source, fatty acids. We hypothesize that WhiB3 is an intracellular redox sensor that maintains redox homeostasis. To better understand the mechanism of this physiological event, we will identify the WhiB3 amino acids necessary for effective iron-sulfur (Fe-S) reconstitution, and use electron paramagnetic resonance spectroscopy (EPR) to characterize these mutated proteins. We will use genome-wide expression profiling to examine the contribution of WhiB3 in maintaining redox homeostasis, and analyze the metabolite profile of MtbwhiB3. These studies will characterize WhiB3 as a potential target for interventions that may abolish virulence, but not growth. These studies will also provide insight into understanding how Mtb subvert host immunity.