EXP2 is a nutrient-permeable channel in the vacuolar membrane of Plasmodium and is essential for protein export via PTEX

Intraerythrocytic malaria parasites reside within a parasitophorous vacuolar membrane (PVM) generated during host cell invasion 1 . Erythrocyte remodelling and parasite metabolism require the export of effector proteins and transport of small molecules across this barrier between the parasite surface and host cell cytosol 2 , 3 . Protein export across the PVM is accomplished by the Plasmodium translocon of exported proteins (PTEX) consisting of three core proteins, the AAA+ ATPase HSP101 and two additional proteins known as PTEX150 and EXP2 4 . Inactivation of HSP101 and PTEX150 arrests protein export across the PVM 5 , 6 , but the contribution of EXP2 to parasite biology is not well understood 7 . A nutrient permeable channel in the PVM has also been characterized electrophysiologically, but its molecular identity is unknown 8 , 9 . Here, using regulated gene expression, mutagenesis and cell-attached patch-clamp measurements, we show that EXP2, the putative membrane-spanning channel of PTEX 4 , 10 – 14 , serves dual roles as a protein-conducting channel in the context of PTEX and as a channel able to facilitate nutrient passage across the PVM independent of HSP101. Our data suggest a dual functionality for a channel operating in its endogenous context. A combination of regulated gene expression, mutagenesis and electrophysiology experiments shows that EXP2, in addition to its role as part of the Plasmodium translocon of exported proteins (PTEX), functions as a nutrient-permeable channel in the vacuolar membrane of the parasite.