The role and fate of Mtb storage lipids LCTAG and MWE

摘要 结核病是传染病导致的主要死亡原因之一，尽管有抗结核药物可用 结核病药物。大多数结核分枝杆菌(Mtb)感染会导致潜伏性结核病，那里的细菌 代谢改变，并表现出表型的药物耐受性。维持新陈代谢的生物途径 人们对动态平衡、燃料复苏和复制知之甚少。 休眠或静止的一个重要组成部分是在细胞壁中储存碳和能源。 复苏后可循环利用的脂类。MTB产生“储存类脂”三酰甘油(TAG)和蜡 酯(WE)处于静止后期，对通常与休眠有关的胁迫做出反应。在.期间 在向活跃复制的过渡过程中，人们认为这些脂质被动员起来，并被用作代谢 资源。然而，这还没有得到实验证明。我们最近描述了非常长的- Mtb的链三酰甘油(LCTAG)和霉酚酸酯(MWE)。这些脂类是从 胞质通过MmpL11转运蛋白进入分枝杆菌外膜或被膜。LCTAG的命运 而MWE一旦进入细胞外就不得而知了。然而，LCTAG和MWE的正确定位是 对结核分枝杆菌的毒力和生理学很重要，因为1)MmpL11是毒力所必需的，2)Mtb的MmpL11 突变减少了来自体外非复制持久性模型的复苏。作为储存脂，表面- 本地化的LCTAG和MWE可以被用作共享资源，以维持生存能力并从 非复制持久性。 根据我们的数据，我们假设结核分枝杆菌可以水解、进口和利用出口的储存脂肪来 促进从低氧和营养受限环境中复苏。 我们建议通过1)确定LCTAG和MWE对Mtb的贡献来检验这一假设 从非复制持久性中复苏，以及2)定义LCTAG和MWE中涉及的蛋白质 生物合成和循环途径。这项探索性研究将不偏不倚的方法与遗传和 生化分析研究结核分枝杆菌胞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.