Molecular mechanisms of Plasmodium fertilization

摘要 疟疾仍然是最具破坏性的传染病之一。它杀死了超过一百万人 每年都在全球造成巨大的痛苦和经济损失。然而， 在了解寄生虫在人类宿主中的生命周期方面取得了进展， 关于蚊子病媒，仍然存在重大的知识空白。疟疾寄生虫的受精是一种 这是一个发生在蚊子肠道内腔的鲜为人知的过程。这个过程是 重要的是，因为在自然界中的生存完全取决于寄生虫的能力， 进行有性生殖。 这项研究旨在确定受精过程中发生的分子相互作用 疟疾寄生虫。这个项目是基于一个非正统的方法（识别肽 结合到配子表面），这是由于最近开发的一种重要工具， 一种转基因寄生虫，能产生红色荧光的雌性配子和绿色荧光的雄性配子， 配子来自这种转基因寄生虫的疟疾雌性和雄性配子的纯种群 通过细胞分选分离，然后用于筛选噬菌体展示文库中的肽， 识别配子表面的分子。一种与雌性配子结合的肽（FG 1） 并鉴定了另一种与雄配子结合的肽（MG 1）。重要的是，当添加 对于疟疾感染性血餐，这些肽中的每一种都阻断了寄生虫受精， 这表明肽与受体结合并阻止其与配体的相互作用， 异性的配子我们的工作假设是这种肽在结构上模拟了 配子配体以及肽和配体竞争结合相应 受体的该提案提出了一项研究计划，以确定FG 1和FG 2的受体。 MG1肽结合和配体上的异性配子，这两个肽 在结构上模仿。另一个目的是表征女性表面的蛋白质组 受精前和受精后的配子，以了解参与受精的其他蛋白质。 受精和可能的多精受精障碍。 阐明施肥机制不仅对理解植物的基本生理过程， 疟疾和其他寄生虫病的生物学，但也可能导致确定新的 阻止疾病传播和蔓延的目标。此外，这些机制是否应 我们的发现可以扩展到高等生物的受精生物学。

ABSTRACT Malaria remains one of the most devastating infectious diseases. It kills over a million people every year while causing immense suffering and economic losses worldwide. Whereas much progress has been made in understanding the life cycle of the parasite in the human host and in the mosquito vector, significant gaps of knowledge remain. Fertilization of malaria parasites is a poorly understood process that takes place in the lumen of the mosquito gut. This process is important because survival in nature is completely dependent on the ability of the parasite to undergo sexual reproduction. The proposed research aims to identify molecular interactions that take place during fertilization of malaria parasites. This project is based on an unorthodox approach (identification of peptides that bind to the gamete surface) made possible by the recent development of an important tool, a transgenic parasite that produces red-fluorescent female gametes and green-fluorescent male gametes. Pure populations of malaria female and male gametes from this transgenic parasite were isolated by cell sorting and then used to screen a phage display library for peptides that recognize molecules on the gamete surfaces. A peptide (FG1) that binds to female gametes and another peptide (MG1) that binds to male gametes were identified. Importantly, when added to a malaria infectious blood meal, each of these peptides blocked parasite fertilization, suggesting that the peptides bound to a receptor and prevented its interaction with a ligand on the gamete of the opposite sex. Our working hypothesis is that the peptide structurally mimics the gamete ligand and that peptide and ligand compete for binding to the corresponding receptor. This proposal lays out a research plan to identify the receptor to which the FG1 and MG1 peptides bind and the ligands on the gametes of the opposite sex that the two peptides structurally mimic. An additional aim is to characterize the proteome on the surface of female gametes before and after fertilization, to gain insights on additional proteins involved in fertilization and possible block to polyspermy. Elucidation of mechanisms of fertilization is important not only for understanding the basic biology of malaria and other parasitic diseases but could also lead to the identification of new targets for blocking transmission and the spread of disease. Moreover, should the mechanisms be conserved, our findings could be extended to the biology of fertilization of higher organisms.