Toxoplasma scavenges mammalian host organelles through usurpation of host ESCRT-III and Vps4

Abstract

Intracellular pathogens exploit cellular resources through host cell manipulation. Within its nonfusogenic parasitophorous vacuole (PV), Toxoplasma targets host nutrient-filled organelles and sequesters them into the PV through deep invaginations of the PV membrane (PVM) that ultimately detach from this membrane. Some of these invaginations are generated by an intravacuolar network (IVN) of parasite-derived tubules fusing with the PVM. Here, we examine the parasite usurpation of host ESCRT-III and Vps4 to create PVM buds and vesicles. CHMP4B associates with the PVM/IVN and dominant negative (DN) CHMP4B forms many long PVM invaginations containing CHMP4B filaments; the invaginations are shorter in IVN-deficient parasites, suggesting cooperation between IVN and ESCRT. In infected cells expressing Vps4-DN, enlarged intra-PV structures containing host endo-lysosomes accumulate, reflecting defects in PVM scission. Parasite mutants lacking TgGRA14 or TgGRA64 that interact with ESCRT have reduced CHMP4B-DN-induced PVM invaginations and intra-PV host organelles, with greater defects in a double-knockout, revealing the exploitation of ESCRT to scavenge host organelles by Toxoplasma. SummaryThe parasite Toxoplasma sequesters host nutrient-filled organelles into its parasitophorous vacuole through its exploitation of host ESCRT-III and Vps4 for vacuolar membrane-remodeling and fission processes utilizing the parasite proteins TgGRA14 and TgGRA64 that interact with ESCRT.