title: Cytoplasmic remodeling of erythrocyte raft lipids during infection by the human malaria parasite Plasmodium falciparum.
abstract: Studies of detergent-resistant membrane (DRM) rafts in mature erythrocytes have facilitated identification of proteins that regulate formation of endovacuolar structures such as the parasitophorous vacuolar membrane (PVM) induced by the malaria parasite Plasmodium falciparum. However, analyses of raft lipids have remained elusive because detergents interfere with lipid detection. Here, we use primaquine to perturb the erythrocyte membrane and induce detergent-free buoyant vesicles, which are enriched in cholesterol and major raft proteins flotillin and stomatin and contain low levels of cytoskeleton, all characteristics of raft microdomains. Lipid mass spectrometry revealed that phosphatidylethanolamine and phosphatidylglycerol are depleted in endovesicles while phosphoinositides are highly enriched, suggesting raft-based endovesiculation can be achieved by simple (non-receptor-mediated) mechanical perturbation of the erythrocyte plasma membrane and results in sorting of inner leaflet phospholipids. Live-cell imaging of lipid-specific protein probes showed that phosphatidylinositol (4,5) bisphosphate (PIP(2)) is highly concentrated in primaquine-induced vesicles, confirming that it is an erythrocyte raft lipid. However, the malarial PVM lacks PIP(2), although another raft lipid, phosphatidylserine, is readily detected. Thus, different remodeling/sorting of cytoplasmic raft phospholipids may occur in distinct endovacuoles. Importantly, erythrocyte raft lipids recruited to the invasion junction by mechanical stimulation may be remodeled by the malaria parasite to establish blood-stage infection.
authors.affiliation: Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Murphy
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fernandez-Pol
authors.forename: Paul H
authors.initials: PH
authors.lastname: Chung
authors.forename: S N
authors.initials: SN
authors.lastname: Prasanna Murthy
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Milne
authors.forename: Marcela
authors.initials: M
authors.lastname: Salomao
authors.forename: H Alex
authors.initials: HA
authors.lastname: Brown
authors.forename: Jon W
authors.initials: JW
authors.lastname: Lomasney
authors.forename: Narla
authors.initials: N
authors.lastname: Mohandas
authors.forename: Kasturi
authors.initials: K
authors.lastname: Haldar
mesh_terms: D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism* / Q000469:parasitology; D004705:Endocytosis; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism* / Q000469:parasitology*; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism; D008288:Malaria / Q000097:blood / Q000473:pathology*; D013058:Mass Spectrometry; D021962:Membrane Microdomains / Q000378:metabolism* / Q000469:parasitology; D018512:Parasitemia / Q000378:metabolism / Q000473:pathology; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D054803:Phospholipase C delta; D010963:Plasmodium falciparum / Q000378:metabolism / Q000472:pathogenicity*; D011319:Primaquine / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
chemical_list: D017304:Annexin A5; D007527:Isoenzymes; D008081:Liposomes; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C483858:phosphatidylethanolamine; D010738:Type C Phospholipases; D054803:Phospholipase C delta; D011319:Primaquine