Anaguano David, Dedkhad Watcharatip, Brooks Carrie F, Cobb David W, Muralidharan Vasant
Department of Cellular Biology, University of Georgia, Athens, GA, USA.
Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA.
J Cell Sci. 2023 Oct 15;136(20). doi: 10.1242/jcs.260506. Epub 2023 Oct 18.
The malaria-causing parasite, Plasmodium falciparum completely remodels its host red blood cell (RBC) through the export of several hundred parasite proteins, including transmembrane proteins, across multiple membranes to the RBC. However, the process by which these exported membrane proteins are extracted from the parasite plasma membrane for export remains unknown. To address this question, we fused the exported membrane protein, skeleton binding protein 1 (SBP1), with TurboID, a rapid, efficient and promiscuous biotin ligase (SBP1TbID). Using time-resolved proximity biotinylation and label-free quantitative proteomics, we identified two groups of SBP1TbID interactors - early interactors (pre-export) and late interactors (post-export). Notably, two promising membrane-associated proteins were identified as pre-export interactors, one of which possesses a predicted translocon domain, that could facilitate the export of membrane proteins. Further investigation using conditional mutants of these candidate proteins showed that these proteins were essential for asexual growth and localize to the host-parasite interface during early stages of the intraerythrocytic cycle. These data suggest that they might play a role in ushering membrane proteins from the parasite plasma membrane for export to the host RBC.
导致疟疾的疟原虫——恶性疟原虫，通过将数百种寄生虫蛋白（包括跨膜蛋白）跨多个膜转运至红细胞，从而彻底重塑其宿主红细胞（RBC）。然而，这些输出的膜蛋白从寄生虫质膜中提取以进行输出的过程仍然未知。为了解决这个问题，我们将输出的膜蛋白——骨架结合蛋白1（SBP1）与TurboID（一种快速、高效且泛用的生物素连接酶）融合（SBP1TbID）。利用时间分辨邻近生物素化和无标记定量蛋白质组学，我们鉴定出两组SBP1TbID相互作用蛋白——早期相互作用蛋白（输出前）和晚期相互作用蛋白（输出后）。值得注意的是，两种有前景的膜相关蛋白被鉴定为输出前相互作用蛋白，其中一种具有预测的转运体结构域，可能有助于膜蛋白的输出。使用这些候选蛋白的条件突变体进行的进一步研究表明，这些蛋白对于无性生长至关重要，并在红细胞内周期的早期定位于宿主 - 寄生虫界面。这些数据表明，它们可能在引导膜蛋白从寄生虫质膜输出到宿主红细胞中发挥作用。
