Analysis of host-derived nutrient utilization pathways in M. tuberculosis

描述（由申请人提供）：结核病（TB）是一种持续的全球流行病，每年夺去约150万人的生命。结核分枝杆菌（Mtb）是TB的病原体，并且该细菌通过在巨噬细胞内存活并操纵宿主免疫应答来建立感染。正是受感染的巨噬细胞协调了肉芽肿的形成，肉芽肿是与结核感染相关的标志性病理损伤。在肉芽肿内分离的结核分枝杆菌可以持续数十年，远离宿主免疫反应的压力。在这种持续感染期间，Mtb必须控制其代谢，以有效地利用宿主来源的营养物质来生存。已经确定，Mtb在感染期间加工和利用宿主来源的脂质营养物的能力对于感染期间的细菌存活是必不可少的。此外，最近的研究表明，结核分枝杆菌不仅利用hos脂质作为营养源，以提供能量产生和/或生物合成途径，但也积极处理有毒代谢产物产生的过程中，宿主脂质catalysts。通过了解结核分枝杆菌中宿主来源的营养代谢途径，我们可能会发现新的弱点，以促进针对这种病原体的新治疗策略的发现。在这个项目中，我们将鉴定几个突变体的遗传筛选，旨在确定新的突变体的宿主营养利用结核分枝杆菌。具体地，该筛选允许鉴定在处理宿主来源的脂质营养物中有缺陷的抑制突变体。 目标1：我们将通过在体外对不同碳源上的生长缺陷进行反筛选来对Mtb突变体进行表型分类，并基于巨噬细胞感染模型中的细胞内适应性对突变体进行优先排序。目的2：将从突变体中扰动的途径中的分解代谢物和生物合成代谢物进行生物化学分类。这些研究将提供新的洞察结核分枝杆菌代谢途径，这是必不可少的感染期间，可能是新的干预策略的目标。

DESCRIPTION (provided by applicant): Tuberculosis (TB) is a lasting global epidemic that claims ~1.5 million human lives annually. Mycobacterium tuberculosis (Mtb) is the causative agent of TB and this bacterium establishes an infection by surviving within macrophages and manipulating the host immune response. It is the infected macrophage that orchestrates the formation of a granuloma, the hallmark pathologic lesion associated with a TB infection. Isolated within the granuloma Mtb can persist for decades sequestered away from the pressures of the host immune response. During this persistent infection Mtb must control its metabolism to efficiently utilize host-derived nutrients for survival. It is well established that Mtb's ability o process and utilize host-derived lipid nutrients during an infection is essential for bacterial survival during an infection. Additionally, recent work has revealed that Mtb not only utilizes hos lipids as a nutrient source to supply energy producing and/or biosynthetic pathways but also actively processes toxic metabolites generated during catabolism of host lipids. By understanding the host-derived nutrient metabolic pathways in Mtb we will likely identify new weaknesses to facilitate the discovery of new therapeutic strategies against this pathogen. For this project we will characterize several mutants identified in a genetic screen designed to identify novel mutants of host nutrient utilization by Mtb. Specifically, this screen allowed for te identification of suppressor mutants that are defective in processing host-derived lipid nutrients. Aim 1: we will phenotypically classify Mtb mutants by counter screening for growth defects on different carbon sources in vitro and prioritize the mutants based on intracellular fitness in a macrophage infection model. Aim 2: will biochemically categorize the catabolic and biosynthetic metabolites from the pathways perturbed in the mutants. These studies will provide novel insight into the Mtb metabolic pathways that are essential during an infection which may be targeted by new intervention strategies.