GAIT complex formation and Mycobacterium tuberculosis

项目摘要 结核病（TB）仍然是一个主要的健康问题，特别是随着全球抗药性结核病的出现， 结核分枝杆菌（Mtb）菌株。世界卫生组织估计，近三分之一的 世界人口目前感染了结核分枝杆菌，使这种杆菌成为最成功的病原体之一， 地球导致结核分枝杆菌成功的一个关键因素是它在宿主巨噬细胞内存活的能力 这种细胞已经进化出捕获和杀死入侵微生物的能力。在吞噬作用之后，Mtb必须 持续监测并适当应对宿主的杀菌活动，以建立安全的避风港 在巨噬细胞的吞噬体内结核分枝杆菌在巨噬细胞内存活的过程是复杂的， 仍然知之甚少。在本申请中，我们提出研究一种新的毒力机制， 劫持干扰素γ激活的翻译抑制剂（GAIT），一种翻译调节机制 通常在人巨噬细胞中由宿主激酶触发，以防止对干扰素-γ的过度反应 (IFNγ），一种由T细胞产生以激活巨噬细胞中的抗微生物活性的促炎细胞因子。我们 初步的数据支持这一假设，即来自结核分枝杆菌的真核型Ser/Thr蛋白激酶G（PknG） 影响60 S-核糖体亚基蛋白L13 a和Glu/Pro-tRNA的磷酸化状态 合成酶，EPRS，导致GAIT以IFNγ非依赖性方式组装。具体实验 目的1旨在确定（i）响应于分枝杆菌感染的GAIT组装的动力学，（ii）响应于分枝杆菌感染的GAIT组装的动力学。 PknG在Mtb诱导的GAIT组装中的作用以及（iii）PknG激酶活性对Mtb内部生长的影响 人原代巨噬细胞。此外，具体目标2中的实验旨在评估影响 Mtb的PknG诱导的GAIT组装对芽孢杆菌细胞内存活的影响。总之，这些建议 实验将阐明GAIT组装对Mtb在人类中存活的生物学相关性 巨噬细胞，并建立Mtb的能力的生物学重要性，通过其PknG，劫持GAIT 组装件.这种分子策略可能允许Mtb使巨噬细胞细胞内环境的抗- 炎症和抗分枝杆菌，以促进其自身的生存。了解如此重要的毒力 这一机制可能有助于开发新的治疗策略，提高我们的先天性抗Mtb活性。 免疫系统

PROJECT SUMMARY Tuberculosis (TB) remains a major health concern, especially with the global emergence of drug resistant Mycobacterium tuberculosis (Mtb) strains. The World Health Organization estimated that nearly one third of the world's population is currently infected with Mtb, making this bacillus one of the most successful pathogens on earth. A key factor that contributes to the success of Mtb is its ability to survive inside macrophage, the host cell that has evolved the ability to capture and kill invading microbes. Following phagocytosis, Mtb must continuously monitor and appropriately respond to host bactericidal activities in order to establish a safe haven inside the macrophage's phagosome. The process by which Mtb survive inside macrophages is complex and still poorly understood. In this application, we propose to study a novel virulence mechanism by which Mtb hijacks the Interferon Gamma Activated Inhibitor of Translation (GAIT), a translational regulatory mechanism normally triggered in human macrophages by host kinases to prevent excessive reactions to interferon-gamma (IFNγ), a pro-inflammatory cytokine produced by T cells to activate antimicrobial activities in macrophages. Our preliminary data support the hypothesis that the eukaryotic-type Ser/Thr protein kinase G (PknG) from Mtb affects the phosphorylation status of the 60S-ribosomal subunit protein L13a, and the Glu/Pro-tRNA synthetase, EPRS, leading to the assembly of GAIT in an IFNγ-independent manner. Experiments in Specific Aim 1 are aimed to determine (i) the kinetics of GAIT assembly in response to mycobacterial infection, (ii) the role of PknG in Mtb-induced GAIT assembly and (iii) the impact of PknG kinase activity on Mtb growth inside human primary macrophages. Furthermore, experiments in Specific Aim 2 are designed to assess the impact of Mtb's PknG-induced GAIT assembly on the bacillus' intracellular survival. Together, these proposed experiments will elucidate the biological relevance of GAIT assembly for Mtb's survival in human macrophages, and establish the biological importance of Mtb's ability, through its PknG, to hijack GAIT assembly. This molecular tactic may allow Mtb to render the macrophage intracellular environment less anti- inflammatory and antimycobacterial, to promote its own survival. Understanding such an important virulence mechanism may help to develop novel therapeutic strategies that boost the innate anti-Mtb activities of our immune system.