GAIT complex formation and Mycobacterium tuberculosis

项目总结 结核病仍然是一个主要的健康问题，特别是在全球出现抗药性的情况下。 结核分支杆菌(Mtb)菌株。世界卫生组织估计，近三分之一的人 世界人口目前感染了结核分枝杆菌，使这种杆菌成为世界上最成功的病原体之一 地球。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。 已经进化出捕获和杀死入侵微生物的能力的细胞。吞噬后，结核分枝杆菌必须 持续监测和适当应对宿主杀菌活动，以建立安全避风港 在巨噬细胞的吞噬小体内。结核分枝杆菌在巨噬细胞内存活的过程是复杂的 人们对此仍知之甚少。在这个应用中，我们建议研究一种新的毒力机制，通过这种机制，结核分枝杆菌 劫持了翻译调控机制--干扰素-伽马激活的翻译抑制因子(GATIT) 通常在人类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 干扰素γ，一种由T细胞产生的促炎细胞因子，用于激活巨噬细胞的抗菌活性。我们的 初步数据支持结核分枝杆菌真核型丝氨酸/苏氨酸蛋白激酶G(PKnG)的假说 影响60S-核糖体亚基蛋白L13a和Glu/Pro-tRNA的磷酸化状态 合成酶，Eprs，导致步态以干扰素γ不依赖的方式组装。在特定情况下的实验 目的1旨在确定(I)分枝杆菌感染后步态组装的动力学，(Ii) PKnG在Mtb诱导的步态组装中的作用及(Iii)pKng活性对Mtb生长的影响 人原代巨噬细胞。此外，特定目标2中的实验旨在评估影响 结核分枝杆菌pnug诱导的步态组装对杆菌细胞内存活的影响。总而言之，这些建议 实验将阐明步态组合与人类多发性结核生存的生物学相关性 巨噬细胞，并确定结核分枝杆菌通过其pKNG劫持步态的能力的生物学重要性 集合。这种分子策略可能允许结核分枝杆菌使巨噬细胞内环境的抗药性降低。 发炎和抗分枝杆菌，促进自身生存。理解如此重要的致命性 机制可能有助于开发新的治疗策略，增强我们的天然抗结核分枝杆菌活性 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.