Protein Secretion Pathways of Mycobacterium tuberculosis

摘要/摘要 结核病仍然是一个严重的全球健康问题。更好地了解结核分枝杆菌， 导致这种疾病的细菌将促进新的抗结核病策略的开发。如中所示 其他细菌病原体，结核分枝杆菌的分泌和表面定位蛋白也有重要作用。 在毒力和宿主免疫力的发展中。这项研究的长期目标是定义 负责将这些蛋白质输出到其适当位置并确定它们在M。 结核病的发病机制。我们的研究有助于证明分枝杆菌具有保守的蛋白质输出。 途径：一般分泌(SEC)途径和双精氨酸转位(TAT)途径。我们也 确定了一个专门的系统，专门用于选择分泌和表面蛋白的子集。这 依赖于SecA2的输出系统对毒力是重要的，正如M。 巨噬细胞和小鼠结核secA2突变体。感染secA2突变体的巨噬细胞产生 更高水平的促炎细胞因子和效应物。我们假设SecA2在毒力中的作用 限制宿主免疫反应，可能是通过调节依赖MyD88的通路。具体的 这项提议的目的如下。1)研究SecA2在限制宿主反应和 通过对SecA2改变的巨噬细胞反应进行全球分析来促进巨噬细胞的生长 并检测免疫调节在巨噬细胞和小鼠中的意义。2)确定依赖于SecA2 利用定量蛋白质组学方法研究SecA2与新发现的DOS的关系 受调控的细胞包膜蛋白。3)通过识别目标来表征SecA2导出的机制 通过识别在出口中与SecA2一起工作的蛋白质，来确定SecA2出口蛋白质中的结构域。这项研究 这项提案将提高我们对SecA2出口制度在M。 结核病的发病机制，将阐明这种新型专业输出的机制基础 路径。这一结果可能揭示疾病干预的新途径，并促进LIVE的建设 分枝杆菌疫苗具有更强的输出和呈递保护性抗原的能力。

SUMMARY/ABSTRACT Tuberculosis remains a severe global health problem. A better understanding of Mycobacterium tuberculosis, the bacterium responsible for this disease, will facilitate development of new anti-tuberculosis strategies. As in other bacterial pathogens, the secreted and surface-localized proteins of M. tuberculosis have important roles in virulence and in the development of host immunity. The long-term objective of this research is to define the systems responsible for exporting these proteins to their proper location and determine the role they play in M. tuberculosis pathogenesis. Our research has helped show mycobacteria to possess conserved protein export pathways: the general secretion (Sec) pathway and the twin-arginine translocation (Tat) pathway. We also identified a specialized system that is dedicated to a select subset of secreted and surface proteins. This SecA2-dependent export system is important to virulence as shown by the attenuated phenotype of a M. tuberculosis secA2 mutant in macrophages and mice. Macrophages infected with the secA2 mutant produce higher levels of pro-inflammatory cytokines and effectors. We hypothesize that the role of SecA2 in virulence is to limit host immune responses, possibly through modulation of MyD88-dependent pathways. The specific aims of this proposal are the following. 1) Investigate the role of SecA2 in limiting host responses and promoting growth in macrophages by performing a global analysis of macrophage responses altered by SecA2 and testing the significance of the immunomodulation in macrophages and mice. 2) Identify SecA2-dependent proteins by quantitative proteomics and study the relationship between SecA2 and newly identified Dos regulated cell envelope proteins. 3) Characterize the mechanism of SecA2 export by identifying targeting domains in SecA2-exported proteins and by identifying proteins that work with SecA2 in export. The research in this proposal will improve our understanding of the role played by the SecA2 export system in M. tuberculosis pathogenesis and it will clarify the mechanistic basis of this new type of specialized export pathway. The results may reveal new approaches for disease intervention and facilitate construction of live mycobacterial vaccines with enhanced ability to export and present protective antigens.