Virulence Regulation by the Mycobacterium Tuberculosis Proteasome

描述（由申请人提供）：结核病每年在全球造成约200万人死亡。针对结核分枝杆菌（Mtb）感染的关键防御是由巨噬细胞产生一氧化氮（NO）。虽然NO控制结核分枝杆菌的生长，但它很少从宿主中杀灭细菌。因此，Mtb可能具有抵抗NO毒性的机制。在Mtb中鉴定了两个基因，mpa（分枝杆菌蛋白酶体ATP酶）和pafA（蛋白酶体相关因子），这是对抗NO保护所需的。重要的是，mpa和pafA突变体在小鼠中严重减毒。蛋白酶体是一种多亚基的桶形复合物，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对抗NO或促进小鼠的毒力。因此，本提案的目标是了解为什么蛋白酶体活性保护Mtb免受NO毒性并促进体内细菌生长。我们将研究蛋白酶体依赖的基因表达，以确定是否由蛋白酶体调控的基因是NO抗性或发病机制所需的。此外，我们将确定基因是如何被蛋白酶体调节的。最后，我们将确定底物的蛋白酶体，这可能会揭示为什么蛋白质降解是至关重要的抵抗NO和生存在体内。与公共卫生的相关性：随着预期年龄的增长、艾滋病毒感染的流行和服用免疫抑制药物的人数的增加，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，并增加了产生耐药性结核分枝杆菌菌株的机会。总之，重要的是开发针对结核分枝杆菌新靶点的速效药物，以便在未来更好地治疗结核病。

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.