The role and fate of Mtb storage lipids LCTAG and MWE

总结 结核病是由于传染病导致死亡的主要原因之一，尽管抗结核药物是可用的。 抗结核药大多数M。结核病（Mtb）感染导致潜伏性结核病， 改变代谢并表现出表型药物耐受性。用于维持代谢的生物途径 体内平衡，然后燃料复苏和复制是知之甚少。 休眠或静止的一个重要组成部分是细胞壁中碳和能源的储存 复苏后可以回收的脂质。结核分枝杆菌产生"储存脂质"三酰甘油（TAG）和蜡 酯（WE）在后期稳定期和响应压力通常与休眠。期间 在向主动复制的转变中，据信这些脂质被动员并用作代谢代谢产物， resource.然而，这还没有得到实验证明。我们最近描述了很长一段时间- 链三酰甘油（LCTAG）和霉菌蜡酯（MWE）的Mtb。这些脂质从 通过MmpL11转运蛋白将细胞质转运至分枝杆菌外膜或包膜。LCTAG的命运 和MWE，一旦它们是细胞外的是未知的。然而，LCTAG和MWE的正确定位是 MmpL11对于Mtb毒力和生理学是重要的，因为1）MmpL11是毒力所需的，2）Mtb mmpL11 突变体从体外非复制持久性模型的复苏减少。作为储存脂质，表面- 局部LCTAG和MWE可用作共享资源，以维持生存力并从 非复制持久性。 基于我们的数据，我们假设Mtb水解、输入和利用输出的储存脂质， 促进从缺氧和营养受限的环境中复苏。 我们建议通过1）确定LCTAG和MWE如何对Mtb做出贡献来检验这一假设 从非复制持久性复苏，和2）定义参与LCTAG和MWE的蛋白质 生物合成和循环途径。这项探索性研究结合了遗传学和 生化分析，以研究Mtb细胞包膜重塑的重要生物学过程， 新陈代谢.

SUMMARY Tuberculosis is one of the leading causes of death due to infectious disease despite the availability of anti- tubercular drugs. The majority of M. tuberculosis (Mtb) infections result in latent TB where bacteria have altered metabolism and exhibit phenotypic drug tolerance. The biological pathways used to maintain metabolic homeostasis and then fuel resuscitation and replication are poorly understood. A crucial component of dormancy or quiescence is the storage of carbon and energy sources in cell wall lipids that can be recycled upon resuscitation. Mtb generates the “storage lipids” triacylglycerol (TAG) and wax esters (WE) in late stationary phase and in response to stresses commonly associated with dormancy. During the transition to active replication, it is believed that these lipids are mobilized and employed as a metabolic resource. However, this has not been experimentally demonstrated. We recently described the Very Long- Chain triacylglycerol (LCTAG) and mycolate wax ester (MWE) of Mtb. These lipids are exported from the cytoplasm to the mycobacterial outer membrane or capsule by the MmpL11 transporter. The fates of LCTAG and MWE once they are extracellular are not known. However, correct localization of LCTAG and MWE is important for Mtb virulence and physiology since 1) MmpL11 is required for virulence and 2) the Mtb mmpL11 mutant has reduced resuscitation from an in vitro non-replicating persistence model. As storage lipids, surface- localized LCTAG and MWE may be utilized as a shared resource to maintain viability and resuscitate from non-replicating persistence. Based on our data, we hypothesize that Mtb hydrolyzes, imports and utilizes exported storage lipids to promote resuscitation from hypoxic and nutrient-restricted environments. We propose to test this hypothesis by 1) Determining how LCTAG and MWE contribute to Mtb resuscitation from non-replicating persistence, and 2) Define proteins involved in the LCTAG and MWE biosynthesis and recycling pathway. This exploratory study combines unbiased approaches with genetic and biochemical analyses to investigate the important biological process of Mtb cell envelope remodeling in metabolism.