Virulence Regulation by the Mycobacterium Tuberculosis Proteasome

描述(申请人提供)：全球每年约有200万人死于结核病。对抗结核分枝杆菌(Mtb)感染的关键防御措施是巨噬细胞产生一氧化氮(NO)。尽管NO可以控制结核分枝杆菌的生长，但它很少对宿主中的细菌进行灭菌。因此，Mtb很可能具有抵抗无毒的机制。在结核分枝杆菌蛋白酶体ATPase(Mpa)和蛋白酶体相关因子PAFA(PAFA)基因中发现了两个基因，它们对NO具有保护作用。重要的是，MPA和PAFA突变体在小鼠体内严重减弱。蛋白酶体是一种多亚单位的桶形复合体，可降解蛋白质。我们假设MPA和PAFA伴侣蛋白进入Mtb蛋白酶体进行降解，但我们不知道为什么这种活性保护Mtb免受NO或促进小鼠的毒力。因此，这项提议的目标是了解为什么蛋白酶体活性保护结核分枝杆菌免受无毒作用，并促进细菌在体内的生长。我们将检测蛋白酶体依赖的基因表达，以确定蛋白酶体调控的基因是否对无耐药性或致病是必需的。此外，我们还将确定蛋白酶体是如何调控基因的。最后，我们将确定蛋白酶体的底物，这可能揭示为什么蛋白质降解对于抵抗NO和体内生存至关重要。与公共卫生的相关性：随着预期年龄的增加、艾滋病毒感染的流行和服用免疫抑制药物的人数增加，感染结核病的机会增加。此外，结核病治疗需要6-9个月，这一问题导致服用抗生素的依从性降低，并增加了产生耐药结核分枝杆菌菌株的机会。总而言之，为了在未来更好地治疗结核病，开发针对结核分枝杆菌新靶点的作用更快的药物将是重要的。

DESCRIPTION (provided by applicant): Tuberculosis kills about 2 million people globally every year. A key defense against Mycobacterium tuberculosis (Mtb) infections is the production of nitric oxide (NO) by macrophages. Although NO controls Mtb growth, it rarely sterilizes the bacterium from the host. Therefore, it is likely that Mtb has mechanisms to resist NO toxicity. Two genes were identified in Mtb, mpa (Mycobacterium proteasome ATPase) and pafA (proteasome associated factor), to be required for protection against NO. Importantly, mpa and pafA mutants are severely attenuated in mice. The proteasome is a multi-subunit, barrel shaped complex that degrades proteins. We hypothesize that Mpa and PafA chaperone proteins into the Mtb proteasome for degradation, but we do not know why this activity protects Mtb against NO or promotes virulence in mice. Thus, the goals of this proposal are to understand why proteasome activity protects Mtb against NO toxicity and promotes bacterial growth in vivo. We will examine proteasome-dependent gene expression to determine if genes regulated by the proteasome are required for NO-resistance or pathogenesis. In addition, we will determine how genes are regulated by the proteasome. Finally, we will identify substrates of the proteasome, which may reveal why protein degradation is critical for resistance to NO and survival in vivo. Relevance to public health: With increased age expectancy, prevalence of HIV infections and number of persons taking immunosuppressive drugs, the chances of contracting tuberculosis increases. Furthermore, tuberculosis therapy takes 6-9 months, a problem that leads to decreased compliance for taking antibiotics and increased chances of developing drug-resistant strains of Mtb. Taken together it will be important to develop faster acting drugs to new targets in Mtb in order to better treat tuberculosis in the future.