The Plasmodial Surface Anion Channel And Malaria Parasit

Apicomplexan分子生理学单位对感染疟疾寄生虫的人类红血球的各种膜上离子和营养物质的运输进行基础研究。这项工作包括分子生物学和信息学，蛋白质和脂肪生物化学，膜蛋白的免疫荧光定位，各种转运分析，生物物理学，化合物文库的高通量筛选，以及小分子抑制剂的构效关系研究。 我们之前在感染恶性疟原虫的人红细胞上发现了一种不寻常的离子通道，恶性疟原虫是最致命的疟疾形式。这种通道，即原生物质表面阴离子通道(PSAC)，存在于1000个拷贝/细胞中，具有不同寻常的门控特性，可以渗透到一系列已知的寄生虫生长所需的阴离子和营养物质中。我们认为PSAC介导了营养获得的连续扩散途径的第一步。目前实验室中的项目包括：1)检测PSAC门控和选择性特性的功能研究；2)高通量筛选以寻找具有治疗潜力的高亲和力、高特异性的PSAC拮抗剂；3)旨在克隆编码PSAC和其他转运体的基因(S)的生化和分子生物学研究；以及4)这些转运体的异源表达。我们这些项目的总体目标是探索PSAC如何实现其不同寻常的功能特性，了解寄生虫的细胞生物学和生理学，并开发控制疟疾的新策略。 在过去的一个财政年度，实验室在这一重要领域做出了几项贡献。一项重要的进展是对PSAC拮抗剂进行了高通量筛选。从不同的化学库中筛选了大约70,000种化合物。从多个结构类中鉴定出新的拮抗剂。这些化合物比以前可用的拮抗剂具有明显更高的亲和力，并正在与疟疾药物风险投资公司合作开发抗疟疾药物。其他重要成就包括证明PSAC在不同的疟疾寄生虫中是保守的，开发了一种新的灌注室，扩大了对小细胞的电生理测量，体外筛选了PSAC的功能突变，在野外分离株中发现了新的PSAC多态，鉴定了第一批PSAC激动剂，克隆和异源表达了疟疾寄生虫新的离子通道候选者，并主办了关于受感染红细胞电生理测量的共识研讨会。

The Apicomplexan Molecular Physiology Unit conducts basic research on the transport of ions and nutrients across various membranes of human red blood cells infected with malaria parasites. This work incorporates molecular biology and informatics, protein and lipid biochemistry, immunofluorescent localization of membrane proteins, various transport assays, biophysics, high-throughput screening of compound libraries, and examination of structure-activity relationships for small molecule inhibitors. We previously identified an unusual ion channel on human red blood cells infected with P. falciparum, which causes the deadliest form of malaria. This channel, the plasmodial surface anion channel (PSAC), is present at 1000 copies/cell, has unusual gating properties, and is permeable to a range of anions and nutrients known to be required for parasite growth. We proposed that PSAC mediates the first step in a sequential diffusive pathway of nutrient acquisition. Current projects in the lab include: 1) functional studies to examine PSAC gating and selectivity properties, 2) high-throughput screening to identify high affinity, high specificity PSAC antagonists with therapeutic potential, 3) biochemical and molecular biological studies aimed at cloning the gene(s) encoding PSAC and other transporters, and 4) heterologous expression of these transporters. Our overall goal with these projects is to probe how PSAC achieves its unusual functional properties, to understand the parasite's cell biology and physiology, and to develop new strategies for the control of malaria. In the past fiscal year, the lab made several contributions to this important field. An important advance was the execution of a high-throughput screen for PSAC antagonists. Approximately 70,000 compounds from diverse chemical libraries were screened. Novel antagonists from multiple structural classes were identified. These compounds have markedly higher affinity than previously available antagonists and are being pursued for antimalarial drug development in collaboration with the Medicines for Malaria Venture. Other important accomplishments include demonstration that PSAC is conserved in divergent malaria parasites, development of a new perfusion chamber that extends electrophysiological measurements on small cells, in vitro selection of functional mutatations in PSAC, discovery of new PSAC polymorphisms in field isolates, identification of the first PSAC agonists, cloning and heterologous expression of novel ion channel candidates from the malaria parasite, and hosting of a consensus workshop on electrophysiological measurements on infected erythrocytes.