MAHRP2 is required for tether formation and cytoadherence in Plasmodium falciparum infected red blood cells

The ability of the human malaria parasite Plasmodium falciparum to remodel its host red blood cell (RBC) is central to the parasite's ability to survive within the circulation of its host and cause disease. Following invasion, the parasite exports proteins into the RBC cytoplasm where they remodel the membrane skeleton and alter the cell's biophysical properties. Many of the exported proteins are trafficked through parasite derived structures called Maurer's clefts in the cytoplasm of the RBC. These clefts act as an intermediate compartment for proteins en route to the RBC membrane such as the major virulence protein, Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1). From the Maurer's clefts, PfEMP1 is delivered to the RBC membrane through a poorly understood process, which may involve trafficking via a physical connection and/or vesicle mediated trafficking. Electron-tomography of 3D7 infected RBCs reveals a tube-like structure, called the tether, that connects the Maurer's clefts to the RBC membrane. To date, the formation and function of these tether structures is unclear, with only one protein, the Membrane Associated Histidine Rich Protein 2 (MAHRP2) known to locate at these structures. In this study, we show that deletion of MAHRP2 leads to a loss of tethers, reduced Maurer's cleft immobilization at the RBC membrane and an increase in Maurer's cleft size. Lastly, we show that deletion of MAHRP2 impacts PTP2 related vesicle formation, and a reduced ability to cytoadhere to the endothelial ligands CD36.