Ethanolamine phospholipid synthesis in Leishmania

本申请的目的是确定利什曼原虫如何获得乙醇胺 磷脂（EPL），一种在膜和非膜中具有重要功能的丰富脂质 流程.这是重要的，因为更好地了解EPL收购将为 利什曼原虫独特的生物化学，结果可能导致新的药物靶点。在许多 在真核生物中，EPL是通过肯尼迪途径的乙醇胺分支产生的， 外源性脂质的重塑，以及磷脂酰丝氨酸和 磷脂酰乙醇胺在它们的生命周期中，利什曼原虫寄生虫在细胞外 白蛉的前鞭毛体和哺乳动物的细胞内无鞭毛体。初步研究表明， 乙醇胺磷酸胞苷酰转移酶（EPCT）对于前鞭毛体是绝对必需的， 大型利什曼原虫的无鞭毛体阶段。EPCT是通过Kennedy酶从头合成EPL所必需的。 通路相比之下，胆碱磷脂的从头合成，其比EPL丰富得多， L.的完全不对称。主要的无鞭毛体，对人类的致病形式。根据这些和其他调查结果， 中心假设是，虽然利什曼原虫无鞭毛体可以通过补救获得大部分脂质， 和重塑，他们必须合成一个特定的子集EPL，不能充分清除从 主持人三个具体的目标将同时进行测试这一假设，并探讨EPL的作用 利什曼原虫的合成目的1是确定为什么EPCT是无鞭毛体必不可少的。计划是 阐明细胞内无鞭毛体的脂质组，鉴定无鞭毛体特异的EPL，并揭示其类型 被无鞭毛体选择性地拯救的宿主脂质。目的2是评估EPCT在以下方面的重要性： 杜氏利什曼原虫和亚马逊利什曼原虫。这很重要，因为不同的利什曼原虫物种 可能对脂质摄取和合成有不同的要求。这一目标将决定EPCT是否是一个泛- 利什曼原虫靶向并鉴定通过EPCT合成的EPL类型。目的3是研究 磷脂酰丝氨酸脱羧酶和磷脂酰丝氨酸合酶。这些酶从未被 研究利什曼原虫及其对EPL合成、线粒体功能和毒力的影响， 测定成功完成这些目标将揭示利什曼原虫如何通过不同的方式获得EPL。 途径和阐明EPL的关键功能。这些发现可能会导致新的药物的识别 靶点（例如EPCT）或新策略来阻断从宿主到利什曼原虫的必需脂质转移。这个项目 在主要研究者的专业领域内，其范围适合研究团队 主要由本科生和研究生组成。总而言之，这一地区赠款预计将改善 我们对利什曼原虫生物学的理解，并扩大德克萨斯理工大学的本科生研究能力 大学

The goal of this application is to determine how Leishmania parasites acquire ethanolamine phospholipids (EPL), an abundant class of lipids with vital functions in membrane- and non-membrane processes. This is significant because a better understanding of EPL acquisition will shed new light on the unique biochemistry of Leishmania parasites and the results may lead to novel drug targets. In many eukaryotes, EPL are generated through the ethanolamine branch of the Kennedy pathway, the uptake and remodeling of exogenous lipids, and the interconversion between phosphatidylserine and phosphatidylethanolamine. During their life cycle, Leishmania parasites alternate between extracellular promastigotes in sandflies and intracellular amastigotes in mammals. Preliminary studies demonstrate that the enzyme ethanolamine-phosphate cytidylyltransferase (EPCT) is absolutely essential for the promastigote AND amastigote stages of Leishmania major. EPCT is required for the de novo synthesis of EPL via the Kennedy pathway. In contrast, the de novo synthesis of choline phospholipids, which are far more abundant than EPL, is fully dispensable for L. major amastigotes, the pathogenic form to humans. Based on these and other findings, the central hypothesis is that while Leishmania amastigotes can acquire most of their lipids through salvage and remodeling, they must synthesize a specific subset of EPL that cannot be sufficiently scavenged from the host. Three specific aims will be undertaken concurrently to test this hypothesis and explore the roles of EPL synthesis in Leishmania. Aim 1 is to determine why EPCT is indispensable for amastigotes. The plan is to elucidate the lipidome of intracellular amastigotes, identify those amastigote specific EPL, and reveal the types of host lipids that are selectively salvaged by amastigotes. Aim 2 is to assess the essentiality of EPCT in Leishmania donovani and Leishmania amazonensis. This is important because different Leishmania species may have distinct requirements for lipid uptake and synthesis. This aim will determine whether EPCT is a pan- Leishmania target and identify the types of EPL that are synthesized via EPCT. Aim 3 is to investigate the roles of phosphatidylserine decarboxylase and phosphatidylserine synthase. These enzymes have never been studied in Leishmania and their impact on in EPL synthesis, mitochondria functions, and virulence will be determined. Successful completion of these aims will reveal how Leishmania acquire EPL through different pathways and elucidate the crucial functions of EPL. The findings may lead to the identification of new drug targets (e.g. EPCT) or new strategies to block the essential lipid transfer from host to Leishmania. This project is well within the principle investigator’s area of expertise and its scope is appropriate for a research team mainly made of undergraduate and graduate students. In summary, this AREA grant is expected to improve our understanding of Leishmania biology and expand the undergraduate research capacity at Texas Tech University.