Burnet Institute, Melbourne, Australia.
Department of Microbiology and Immunology, University of Melbourne, Melbourne, Australia.
Cell Microbiol. 2021 Aug;23(8):e13332. doi: 10.1111/cmi.13332. Epub 2021 May 3.
During its intraerythrocytic life cycle, the human malaria parasite Plasmodium falciparum supplements its nutritional requirements by scavenging substrates from the plasma through the new permeability pathways (NPPs) installed in the red blood cell (RBC) membrane. Parasite proteins of the RhopH complex: CLAG3, RhopH2, RhopH3, have been implicated in NPP activity. Here, we studied 13 exported proteins previously hypothesised to interact with RhopH2, to study their potential contribution to the function of NPPs. NPP activity assays revealed that the 13 proteins do not appear to be individually important for NPP function, as conditional knockdown of these proteins had no effect on sorbitol uptake. Intriguingly, reciprocal immunoprecipitation assays showed that five of the 13 proteins interact with all members of the RhopH complex, with PF3D7_1401200 showing the strongest association. Mass spectrometry-based proteomics further identified new protein complexes; a cytoskeletal complex and a Maurer's clefts/J-dot complex, which overall helps clarify protein-protein interactions within the infected RBC (iRBC) and is suggestive of the potential trafficking route of the RhopH complex itself to the RBC membrane.
在其红细胞内生命周期中，人类疟原虫通过在红细胞（RBC）膜中安装新的通透性途径（NPP）从血浆中掠夺底物来补充其营养需求。RhopH 复合物的寄生虫蛋白：CLAG3、RhopH2、RhopH3，被认为与 NPP 活性有关。在这里，我们研究了之前假设与 RhopH2 相互作用的 13 种分泌蛋白，以研究它们对 NPP 功能的潜在贡献。NPP 活性测定表明，这 13 种蛋白似乎都不是 NPP 功能的重要组成部分，因为这些蛋白的条件敲低对山梨醇摄取没有影响。有趣的是，相互免疫沉淀测定表明，这 13 种蛋白中的 5 种与 RhopH 复合物的所有成员相互作用，PF3D7_1401200 表现出最强的关联。基于质谱的蛋白质组学进一步鉴定了新的蛋白质复合物；一个细胞骨架复合物和一个 Maurer 的裂隙/J 点复合物，这总体上有助于澄清感染红细胞（iRBC）内的蛋白质-蛋白质相互作用，并暗示 RhopH 复合物本身到 RBC 膜的潜在运输途径。
