Inner membrane complex proteomics reveals a palmitoylation cascade regulating intraerythrocytic development of malaria parasite

Malaria is caused by infection of the erythrocytes by the parasites Plasmodium. Inside the erythrocytes, the parasites multiply via schizogony, an unconventional cell division mode. The Inner Membrane Complex (IMC), an organelle located beneath the parasite plasma membrane, serving as the platform for protein anchorage, is essential for schizogony. So far, complete repertoire of IMC proteins and their localization determinants remain unclear. Here we used biotin ligase (TurboID)-based proximity labelling to compile the proteome of the schizont IMC of rodent malaria parasite Plasmodium yoelii. In total, 300 TurboID-interacting proteins were identified. 19 of the 22 selected candidates were confirmed to localize in the IMC, indicating good reliability. In light of the existing palmitome of Plasmodium falciparum, 83 proteins of the P. yoelii IMC proteome are potentially palmitoylated. We further identified DHHC2 as the major resident palmitoyl-acyl-transferase of the IMC. Depletion of DHHC2 led to defective schizont segmentation and growth arrest both in vitro and in vivo. DHHC2 was found to palmitoylate two critical IMC proteins CDPK1 and GAP45 for their IMC localization. In summary, this study reports an inventory of new IMC proteins and demonstrates a central role of DHHC2 in governing IMC localization of proteins during the schizont development.