Molecular Analysis of the PfEMP1 Binding Activity

描述（由申请方提供）：恶性疟原虫感染的红细胞（IE）在宿主体内持续存在，并通过改变IE表面称为恶性疟原虫红细胞膜蛋白1（PfEMP 1）的细胞粘附蛋白家族的表达来避免在脾脏中清除。不同的PfEMP1结合不同的宿主受体，从而靶向IE以隔离不同器官的微血管系统，这反过来又决定了疾病的严重程度。PfEMP 1表面转运是一个多步骤的过程，涉及蛋白质跨寄生虫空泡膜（PVM）（早期转运）和蛋白质通过红细胞质（通过Maurer's裂隙细胞器）转移到IE表面（晚期转运）。每种寄生虫基因组编码约60种PfEMP1蛋白，这些蛋白以相互排斥的方式表达。大多数蛋白质与宿主受体CD36结合，除了一种异常保守的PfEMP 1变体，它介导胎盘中受感染的红细胞隔离。该项目旨在阐明PfEMP1在IE表面转运和组装的重要决定因素，并定义PfEMP1蛋白如何进化以维持关键的结合相互作用，尽管强烈的抗体压力。采用异源重组蛋白和表达转基因miniPfEMP1蛋白的寄生虫系的体外和体内测定的组合将用于定义参与PfEMP1转运和功能的辅助蛋白，并绘制细胞粘附中的关键相互作用残基。这些研究将有助于详细描述恶性疟原虫感染红细胞的细胞粘附特性，并使人们能够更好地了解疟疾发病机制的分子基础。

DESCRIPTION (provided by applicant): Plasmodium falciparum infected erythrocytes (IEs) persist in the host and avoid clearance in the spleen by varying expression of a family of cytoadhesion proteins at the IE surface called P. falciparum erythrocyte membrane protein 1 (PfEMP1). Different PfEMP1s bind to different host receptors and thereby target IEs to sequester in the microvasculature of different organs, which in turn determines disease severity. PfEMP1 surface transport is a multi-step process that involves protein export across the parasitophorus vacuole membrane (PVM) (early transport) and protein transfer through the erythrocyte cytoplasm (via Maurer's cleft organelles) to the IE surface (late transport). Each parasite genome encodes ~60 PfEMP1 proteins that are expressed in a mutually exclusion fashion. Most proteins bind to the host receptor CD36, except for an unusually conserved PfEMP1 variant that mediates infected erythrocyte sequestration in the placenta. This project is designed to elucidate important determinants in PfEMP1 transport and assembly at the IE surface and define how PfEMP1 proteins have evolved to maintain key binding interactions despite intense antibody pressure. A combination of in vitro and in vivo assays employing heterologous recombinant proteins and parasite lines expressing transgenic miniPfEMP1 proteins will be used to define accessory proteins involved in PfEMP1 transport and function and to map critical interaction residues in cytoadhesion. These studies will contribute to a detail characterization of the cytoadhesive properties of P. falciparum infected erythrocytes and enable a greater understanding of the molecular basis of malaria pathogenesis.