Characterization of isoprenoid biosynthesis in human malaria gametocytes

说明(申请人提供)：世界上40%以上的人口面临感染疟疾的风险，抗药性是一个长期存在的问题；因此，迫切需要确定和确定具有不同作用模式的抗疟疾药物开发的新目标。此外，抗配子细胞新药的活性--疟疾的传播阶段--被认为是根除疟疾努力的优先事项。这个 异戊二烯生物合成途径是疟疾特异靶标的一个很有前途的来源，因为：a)它通过存在于顶体中的疟疾寄生虫中的甲基赤藓糖醇磷酸途径发生，而在人类中不存在；b)异戊二烯下游产物不同于人类宿主中的产物；以及c)异戊二烯类化合物参与了广泛的重要生物学功能。我们关于类异戊二烯生物合成的大部分知识来自于仅在无性红细胞内阶段进行的研究。然而，尚不清楚：a)类异戊二烯的生物合成是否发生在配子细胞发生过程中，b)类异戊二烯的合成是否与无性阶段的合成类似。 以及c)类异戊二烯在配子体发生中的作用。我们假设类异戊二烯的生物合成存在于配子体阶段，是配子体发生所必需的。此外，我们还发现了一种新的异戊二烯类产物--孟喹酮的生物合成途径。因此，这项应用的首要目标是研究疟疾配子体阶段的类异戊二烯生物合成，并表征疟疾寄生虫中的甲喹酮生物合成。为了达到这些目标，我们将主要使用13C代谢标记和最先进的质谱分析相结合。在这些研究的基础上，这项提议的长期目标是确定新的靶点，并验证配子细胞中的已知靶点，用于未来治疗疟疾和阻止其传播的药物开发。

DESCRIPTION (provided by applicant): More than 40% of the world's population is at risk of contracting malaria and drug resistance is a constant problem; thus, identification and characterization of new targets for development of antimalarial drugs with different modes of action is critically needed. Moreover, the activity of new drugs against gametocytes, the transmission stage of malaria, is recognized as a priority in the efforts to eradicate malaria. The isoprenoid biosynthetic pathway is a promising source of malaria-specific targets because: a) it occurs through the methylerythritol phosphate pathway in malaria parasites present in the apicoplast and is absent in humans; b) isoprenoid downstream products differ from those in the human host; and c) isoprenoids are involved in a wide variety of vital biological functions. Most of our knowledge about isoprenoid biosynthesis comes from studies performed in the asexual intraerythrocytic stages only. However, it is unknown: a) if isoprenoid biosynthesis occurs during gametocytogenesis, b) if the isoprenoid repertoire is similar to that present in the asexual stages and c) what the role of the isoprenoids are during gametocytogenesis. We hypothesize that isoprenoid biosynthesis is present in gametocyte stages and is essential for gametocytogenesis. In addition, we have identified a novel pathway for menaquinone biosynthesis, an isoprenoid product. Thus, the overarching goal of this application is to study isoprenoid biosynthesis in the malaria gametocyte stages and to characterize the menaquinone biosynthesis in the malaria parasites. To address these aims we will mainly use 13C-metabolic labeling in combination with state-of-the-art mass spectrometry analysis. Building on these studies, the long- term goal of this proposal is to identify novel targets and to validate known targets in gametocytes for future drug development to cure malaria and stop its transmission.