Elucidating the trafficking mechanisms of effector proteins to the Plasmodium infected red blood cell

项目概要 恶性疟原虫是一种致命的人类寄生虫，可引起疟疾，导致近 45 万人死亡 每年都有死亡。疟疾在世界大部分地区流行，这些地区约有 40 亿人口。 每年影响约 2.5 亿人。没有有效的疟疾疫苗和抗疟药物 是治疗的支柱。此时，寄生虫已获得对所有临床可用药物的抵抗力 抗疟药物和这些耐药菌株正在全世界蔓延，威胁着所有人类 过去十年来对抗这种疾病所取得的进展。因此，我们当务之急是 不断生产新药并确定潜在的药物靶标，以领先于这种邪恶的疾病。的 这种毁灭性寄生虫病的临床表现（包括死亡）是由疟原虫的生长引起的。 宿主红细胞（RBC）内的恶性疟原虫。为了在红细胞内部建立一个适合生长的栖息地，疟疾 寄生虫完全改变了宿主细胞。它改变了红细胞的新陈代谢，使红细胞变得更加坚硬 使受感染的红细胞更难通过毛细血管，修改红细胞膜以允许 营养物质的有利运动，并改变红细胞的结合特性，以便受感染的细胞可以结合 到血管内壁的内皮细胞。这些变化的总和会导致疾病和死亡，因为 例如，恶性疟原虫感染的红细胞与内皮细胞的结合会堵塞大脑中的血管 导致血栓，最终导致死亡。对受感染红细胞的抑制是通过 寄生虫通过知之甚少的方式将数百种蛋白质转运至宿主细胞 机制。寄生虫效应蛋白的输出对于红细胞的转化至关重要，因此，对于 引起疾病。在寄生虫细胞质中合成的寄生虫效应蛋白需要 转运穿过三个或四个细胞膜以到达宿主红细胞中的作用位点。的 识别、分类并将这些寄生虫效应物转运至受感染红细胞的分子机制仍然存在 待识别。拟议的研究旨在揭示控制关键早期事件的分子过程 在通往宿主 RBC 的路径上设置寄生效应器。为了实现这一目标，我们将追求两个目标。首先，我们 将在寄生虫的内质网中产生蛋白质的条件突变体，这些突变体可能是 寄生效应器出口所需。将使用遗传、细胞和生物化学方法对突变体进行分析 确定它们在寄生虫蛋白输出中的作用的方法。其次，我们将秉持公正的态度 相互作用组筛选方法，使用基于邻近的标记方法并发现蛋白质 usher 将蛋白质输出到宿主红细胞中的作用位点。实现研究计划的目标 将揭示恶性疟原虫关键且独特的蛋白质运输机制，可能成为抗疟疾的目标 药物开发。

Project Summary Plasmodium falciparum is a deadly human parasite that causes malaria and is responsible for nearly 450,000 deaths every year. Malaria is endemic in large regions of the world, home to about 4 billion people and it affects ~250 million people annually. There are no effective vaccines against malaria and antimalarial drugs are the mainstay of treatment. At this time, the parasite has gained resistance to all clinically available antimalarial drugs and these drug-resistant strains are spreading throughout the world, threatening all the progress that has been made against this disease in the last decade. Therefore, it is imperative that we constantly generate new drugs and identify potential drug targets to stay ahead of this nefarious disease. The clinical manifestations of this devastating parasitic disease, including death, are caused by the growth of P. falciparum within the host red blood cell (RBC). To build a suitable habitat for growth inside RBCs, the malaria parasite completely transforms the host cell. It changes the metabolism of the RBC, makes the RBC more rigid such that it is harder for the infected RBC to pass through capillaries, modifies the RBC membrane to allow for favorable movement of nutrients, and alters the binding properties of the RBC so that the infected cell can bind to the endothelial cells lining blood vessels. The sum of these changes leads to disease and death, for instance, binding of the P. falciparum infected RBC to endothelial cells can clog blood vessels in the brain leading to clots that eventually result in death. The subjugation of the infected RBC is accomplished through the action of several hundred proteins that the parasite transports to the host cell via poorly understood mechanisms. The export of parasite effector proteins is essential for transforming the RBC and therefore, for causing disease. Parasite effector proteins that are synthesized in the parasite cytoplasm need to be transported across three or four cellular membranes in order to reach their site of action in the host RBC. The molecular mechanisms that recognize, sort, and transport these parasite effectors to the infected RBC remain to be identified. The proposed studies aim to unravel the molecular processes that govern key early events that set parasite effectors on the path to the host RBC. We will pursue two aims to accomplish this goal. First, we will generate conditional mutants of proteins in the endoplasmic reticulum of the parasite that are potentially required for export of parasite effectors. The mutants will be analyzed using genetic, cellular, and biochemical approaches to determine their roles in the export of parasite proteins. Second, we will take an unbiased interactome screening approach that uses a proximity-based labeling approach and discover proteins that usher exported proteins to their site of action in the host RBC. Attaining the objectives of the research program will reveal key and unique protein trafficking mechanisms of P. falciparum that may be targeted for antimalarial drug development.