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。正是被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病变。孤立在肉芽肿内的结核可持续数十年，远离宿主免疫反应的压力。在这种持续感染中，结核分枝杆菌必须控制其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加工和利用宿主来源的脂质营养物质的能力对细菌在感染期间的生存至关重要。此外，最近的研究表明，结核分枝杆菌不仅利用宿主脂质作为营养来源提供能量产生和/或生物合成途径，而且还积极处理宿主脂质分解代谢过程中产生的有毒代谢物。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，从而促进发现针对这种病原体的新治疗策略。在这个项目中，我们将描述在基因筛选中鉴定出的几种突变体，这些突变体旨在鉴定结核分枝杆菌对宿主养分利用的新突变体。具体来说，这种筛选允许识别在处理宿主来源的脂质营养素方面有缺陷的抑制突变体。

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.