A novel protein export chaperone of Mycobacterium tuberculosis

结核分枝杆菌(Mtb)是结核病(TB)的病原体，代表着严重的世界健康。 危机(每天有4000人死于结核病)。更好地了解结核分枝杆菌的生物学和发病机制将推动发展 控制结核病流行的新战略。在细菌病原体中，如结核分枝杆菌，许多蛋白质被输出到 细菌的细胞膜或细胞外环境，以便在细菌中执行关键功能 生理、毒性或免疫反应。因此，输出蛋白质的Mtb途径可能是靶点或 被开发用于开发新的抗结核病控制措施。然而，在我们的国家中存在着显著的差距 了解结核分枝杆菌蛋白出口。 本研究旨在探讨我们发现的一种新的蛋白质输出伴侣蛋白--饱和脂肪酸的作用机制 在Mtb。Sts是由专门的SecA2蛋白质出口输出的蛋白质子集的伴侣 在巨噬细胞中，结核分枝杆菌的细胞内生长需要SATS。然而，SAT并不共享 与任何以前表征的蛋白质的序列或结构相似，并且SATS的机制是 完全未知。底物专一性和SATS底物的范围也是未知的。目标1 建议确定SATS在蛋白质出口中作用的机制细节。目标2是确定 SAT的结构以及与底物的多肽形成的复合物的结构。目标3是确定与SAT的结合 以确定更多的SATS底物。通过实现这些目标，我们将确定 小卫星对结核分枝杆菌蛋白输出和生物学的作用机制和贡献。更广泛地说，这些研究将 提高我们对细菌输出蛋白质的策略和分子多样性的理解 生物系统中的伴侣。从长远来看，这一结果可能导致抑制蛋白质的策略 EXPORT作为一种新的抗结核病疗法。或者，可以将所获得的知识用于工程设计 分枝杆菌菌株具有更好的输出蛋白质作为实验工具或活的能力， 加强抗原输出的减毒疫苗。

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), represents a severe world health crisis (4,000 TB deaths daily). A better understanding of Mtb biology and pathogenesis will drive development of novel strategies to control the TB epidemic. In bacterial pathogens, like Mtb, many proteins are exported to the bacterial cell envelope or the extracellular environment in order to carry out critical functions in bacterial physiology, virulence or immune responses. Thus, Mtb pathways that export proteins could be targeted or exploited for the development of novel anti-TB control measures. However, significant gaps exist in our understanding of Mtb protein export. This proposal is to determine the mechanism of SatS, a novel protein export chaperone we discovered in Mtb. SatS is a chaperone for a subset of proteins that are exported by the specialized SecA2 protein export pathway, and SatS is required for intracellular growth of Mtb in macrophages. However, SatS shares no sequence or structural similarity with any previously characterized proteins and the mechanism of SatS is completely unknown. Substrate specificity and the scope of SatS substrates are also unknown. Aim 1 of this proposal is to determine the mechanistic details of SatS function in protein export. Aim 2 is to determine the structures of SatS and that of SatS in complex with peptides of substrates. Aim 3 is to identify SatS-binding sites in substrates and to identify additional SatS substrates. By completing these Aims, we will determine the mechanism and contribution of SatS to Mtb protein export and biology. More broadly, these studies will improve our understanding of bacterial strategies for exporting proteins and of the diversity of molecular chaperones across biological systems. Long-term, the results could lead to strategies for inhibiting protein export as a novel anti-TB therapy. Alternatively, the knowledge gained could be harnessed to engineer mycobacterial strains with improved capacity to export proteins for use as experimental tools or as live, attenuated vaccines with enhanced antigen export.