Transcriptional regulation of lipid homeostasis in mycobacteria

描述（由申请人提供）：结核分枝杆菌是人类结核病（TB）的病原体，仍然是全球主要的健康问题。分枝杆菌酸是分枝杆菌外膜最重要的脂质之一，与细菌的毒力和抗生素耐药性密切相关，其生物合成途径是结核病治疗的主要靶点之一。分枝菌酸的生物合成涉及两个结构不同的脂肪酸合成酶系统，FAS-I和FAS-II，它们应该以精细的协调方式工作，以保持脂质稳态的严格调节。该提案的主要目标是了解分枝杆菌如何对其膜脂质的生物合成施加这种精细控制，并找出在转录水平上控制脂肪酸和分枝菌酸生物合成的调控网络的关键组成部分。为了实现这些目标，我们建议使用一个多学科的方法，包括遗传分析的条件突变株的fas和mabR（转录调节因子的主要fasII操纵子），无论是在耻垢分枝杆菌和M。结核病，通过使用生物化学和光谱技术鉴定和表征由MabR和参与FAS-I/FAS-II调节网络的任何其他调节蛋白感知的代谢信号，以及最后通过X射线晶体学确定MabR结构。更好地了解这种复杂的过程中的脂质稳态的调节分枝杆菌将大大有助于新的策略，以控制这种疾病的发展，包括设计或鉴定的化合物，可以解除脂肪酸的生物合成和诱导细菌死亡。 公共卫生相关性：由于脂肪酸的生物合成是必不可少的，并且能量昂贵，生物体已经开发出了维持脂质浓度严格调节的机制。In M.在结核病（结核病的病原体）中，脂肪酸生物合成甚至更相关，因为这些分子也是其它更复杂的脂质（分枝菌酸）的前体，分枝菌酸对于赋予这些生物体毒性和抗生素抗性是必需的。这些代谢途径的生物合成需要严格调节，这种调节的破坏对细胞存活具有高度破坏性。我们的项目建议识别和表征这个复杂的调控网络的所有组成部分，并希望识别新的药物靶点，这些靶点可以通过影响脂质代谢来发挥作用。

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis, the etiologic agent of tuberculosis (TB) in humans, continues to be a major health problem worldwide. Mycolic acids, one of the most important lipids of the outer membrane of mycobacteria, have been largely associated with bacterial virulence and antibiotic resistance and its biosynthesis pathway is one of the main targets for TB treatment. Biosynthesis of mycolic acids involves two structural distinct fatty acid synthase systems, FAS-I and FAS-II, which should work in a finely coordinate manner to keep lipid homeostasis tightly regulated. The main goal of this proposal is to understand how mycobacteria exert this exquisite control over the biosynthesis of their membrane lipids and find out the key components of the regulatory network that control fatty acid and mycolic acid biosynthesis at the transcriptional level. To achieve these goals we propose to use a multidisciplinary approach including genetic analysis of conditional mutant strains in fas and mabR (the transcriptional regulator of the main fasII operon), both in Mycobacterium smegmatis and M. tuberculosis, the identification and characterization of the metabolic signals that are sensed by MabR and any other regulatory proteins involved in the FAS-I/FAS-II regulatory network, by using biochemical and spectroscopic techniques, and finally the determination of MabR structure by X-ray crystallography. A better understanding of this complex process of regulation of lipid homeostasis in mycobacteria will greatly contribute to the development of new strategies to control this disease, including the design or identification of compounds that could deregulate fatty acid biosynthesis and induce bacterial death. PUBLIC HEALTH RELEVANCE: Since fatty acid biosynthesis is essential and energetically expensive, organisms have developed mechanisms that maintain the concentration of lipids tightly regulated. In M. tuberculosis, the etiological agent of tuberculosis, fatty acid biosynthesis is even more relevant since these molecules are also the precursors of other more complex lipids, the mycolic acids, which are essential for conferring virulence and antibiotic resistance to these organisms. Biosynthesis of these metabolic pathways needs to be tightly regulated and disruption of this regulation should be highly damaging for cell survival. Our project proposes to identify and characterize all the components of this complex net of regulation and hopefully identify new drug targets that could act by globally affecting lipid metabolism.