The role and fate of Mtb storage lipids LCTAG and MWE

摘要 尽管有抗结核药物可用，但结核病仍是传染病导致死亡的主要原因之一。 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，其中细菌已存在 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 人们对体内平衡、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细胞壁中碳和能源的储存 复苏后可回收的脂质。 Mtb 产生“储存脂质”三酰甘油 (TAG) 和蜡 酯（WE）处于稳定期后期并响应通常与休眠相关的应激。期间 在向主动复制的转变过程中，人们相信这些脂质被动员起来并用作代谢物质 资源。然而，这尚未得到实验证明。我们最近描述了非常长的 Mtb 的链三酰甘油 (LCTAG) 和霉菌蜡酯 (MWE)。这些脂质是从 通过 MmpL11 转运蛋白将细胞质转运至分枝杆菌外膜或荚膜。 LCTAG 的命运 一旦它们进入细胞外，MWE 和 MWE 是未知的。然而，LCTAG 和 MWE 的正确定位是 对于 Mtb 毒力和生理学很重要，因为 1) MmpL11 是毒力所必需的，2) Mtb mmpL11 突变体减少了体外非复制持久性模型的复苏。作为储存脂质，表面 本地化的 LCTAG 和 MWE 可用作共享资源，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 Mtb 会水解、进口和利用出口的储存脂质 促进缺氧和营养受限环境中的复苏。 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) 定义参与 LCTAG 和 MWE 的蛋白质 生物合成和回收途径。这项探索性研究将公正的方法与遗传和 生化分析研究 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.