PROTEASOME-DEPENDENT DEGRADATION IN MYCOBACTERIUM TUBERCULOSIS

 描述（由申请人提供）：结核病（TB）每年在全球造成约150万人死亡，使其成为细菌病原体导致死亡的主要原因。缺乏有效的结核病疫苗或结核病感染后保护性免疫的发展表明，抗微生物药物可能是我们控制这种疾病的最佳机会。目前的治疗是长期和有毒的，耐药性正在上升。因此，结核病领域迫切希望找到毒性更小、对耐药菌株更有效的新药。结核分枝杆菌（Mtb）蛋白酶体是这种细菌在动物中引起致命感染所必需的;因此，我们希望了解蛋白酶体功能如何与Mtb生理学联系起来，以及靶向蛋白酶体及其辅助因子用于药物开发。蛋白酶体是一种多亚基的桶形复合物，可降解蛋白质。我们发现，蛋白质降解所需的酶包括PafA和Mpa，PafA将原核泛素样蛋白（Pup）连接到靶向破坏的底物上，Mpa是一种ATP酶伴侣，识别pupylated蛋白并将其展开以递送到Mtb蛋白酶体核心。Pup也可以通过称为Dop的高度独特的蛋白酶从底物中去除。最近，我们发现了一种名为PafE的新辅因子，它形成十二聚体环，打开蛋白酶体，以不依赖ATP的方式降解蛋白质。有趣的是，PafE不需要Pup或任何其他翻译后修饰来识别蛋白质进行降解。该提案概述了实验，将确定如何选择蛋白质Pup/Mpa依赖和PafE依赖的蛋白酶体降解，并确定PafE依赖的底物对结核分枝杆菌的生理和发病机制的作用。

 DESCRIPTION (provided by applicant): Tuberculosis (TB) kills about 1.5 million people globally every year, making it the leading cause of death by a bacterial pathogen. The lack of an effective TB vaccine or the development of protective immunity after TB infection suggests antimicrobial drugs may be our best chance for controlling this disease. Current therapies are prolonged and toxic, and drug resistance is on the rise. Thus the TB field is eager to identify new drugs that are less toxic as well as more efficacious against drug-resistant strains. The Mycobacterium tuberculosis (Mtb) proteasome is essential for this bacterium to cause lethal infections in animals; thus, we want to understand how proteasome function is linked to Mtb physiology as well as target the proteasome and its co-factors for drug development. The proteasome is a multi-subunit, barrel shaped complex that degrades proteins. We found that enzymes required for protein degradation include PafA, which attaches prokaryotic ubiquitin-like protein (Pup) onto substrates targeted for destruction, and Mpa, which is an ATPase chaperone that recognizes pupylated proteins and unfolds them for delivery into the Mtb proteasome core. Pup can also be removed from substrates by a highly unique protease called Dop. More recently, we discovered a new co-factor called PafE, which forms dodecameric rings that open the proteasome to degrade proteins in an ATP-independent manner. Interestingly, PafE does not require Pup or any other post-translational modification to recognize proteins for degradation. This proposal outlines experiments that will determine how proteins are selected for Pup/Mpa-dependent and PafE-dependent proteasomal degradation, and determine the roles of PafE-dependent substrates on Mtb physiology and pathogenesis.