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

描述(申请人提供)：结核病(TB)是一种持久的全球流行病，每年夺走约150万人的生命。结核分枝杆菌(Mtb)是结核病的病原体，这种细菌通过在巨噬细胞内存活并操纵宿主免疫反应来建立感染。是受感染的巨噬细胞协调肉芽肿的形成，肉芽肿是与结核病感染相关的标志性病理损害。分离于肉芽肿内的结核分枝杆菌可持续数十年，远离宿主免疫反应的压力。在这种持续感染期间，结核分枝杆菌必须控制其新陈代谢，以有效地利用宿主来源的营养物质生存。众所周知，结核分枝杆菌在感染期间处理和利用宿主来源的脂质营养的能力对于细菌在感染期间的生存是必不可少的。此外，最近的研究表明，MTB不仅利用宿主脂类作为营养来源来提供能量产生和/或生物合成途径，而且还积极处理宿主脂类分解代谢过程中产生的有毒代谢产物。通过了解结核分枝杆菌宿主来源的营养代谢途径，我们可能会发现新的弱点，以促进发现针对这种病原体的新治疗策略。在这个项目中，我们将对在遗传筛选中确定的几个突变进行表征，该筛选旨在确定结核分枝杆菌对宿主养分利用的新突变。具体地说，这一筛选允许鉴定在处理宿主来源的脂肪营养方面有缺陷的抑制突变体。 目的1：我们将通过体外反筛选不同碳源的生长缺陷来对Mtb突变体进行表型分类，并在巨噬细胞感染模型中基于细胞内适合性对突变体进行优先排序。目的2：从生物化学的角度对突变体中干扰的代谢途径中的分解代谢产物和生物合成代谢产物进行分类。这些研究将为结核分枝杆菌代谢途径提供新的见解，这些途径在感染期间是必不可少的，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.