title: Selective permeabilization of the host cell membrane of Plasmodium falciparum-infected red blood cells with streptolysin O and equinatoxin II.
abstract: Plasmodium falciparum develops within the mature RBCs (red blood cells) of its human host in a PV (parasitophorous vacuole) that separates the host cell cytoplasm from the parasite surface. The pore-forming toxin, SLO (streptolysin O), binds to cholesterol-containing membranes and can be used to selectively permeabilize the host cell membrane while leaving the PV membrane intact. We found that in mixtures of infected and uninfected RBCs, SLO preferentially lyses uninfected RBCs rather than infected RBCs, presumably because of differences in cholesterol content of the limiting membrane. This provides a means of generating pure preparations of viable ring stage infected RBCs. As an alternative permeabilizing agent we have characterized EqtII (equinatoxin II), a eukaryotic pore-forming toxin that binds preferentially to sphingomyelin-containing membranes. EqtII lyses the limiting membrane of infected and uninfected RBCs with similar efficiency but does not disrupt the PV membrane. It generates pores of up to 100 nm, which allow entry of antibodies for immunofluorescence and immunogold labelling. The present study provides novel tools for the analysis of this important human pathogen and highlights differences between Plasmodium-infected and uninfected RBCs.
authors.affiliation: Department of Biochemistry, La Trobe University, Melbourne, VIC 3086, Australia.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Jackson
authors.forename: Tobias
authors.initials: T
authors.lastname: Spielmann
authors.forename: Eric
authors.initials: E
authors.lastname: Hanssen
authors.forename: Akinola
authors.initials: A
authors.lastname: Adisa
authors.forename: Frances
authors.initials: F
authors.lastname: Separovic
authors.forename: Matthew W A
authors.initials: MW
authors.lastname: Dixon
authors.forename: Katharine R
authors.initials: KR
authors.lastname: Trenholme
authors.forename: Paula L
authors.initials: PL
authors.lastname: Hawthorne
authors.forename: Don L
authors.initials: DL
authors.lastname: Gardiner
authors.forename: Tim
authors.initials: T
authors.lastname: Gilberger
authors.forename: Leann
authors.initials: L
authors.lastname: Tilley
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003064:Cnidarian Venoms / Q000494:pharmacology*; D003603:Cytotoxins / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D018512:Parasitemia / Q000097:blood; D010963:Plasmodium falciparum / Q000472:pathogenicity*; D013301:Streptolysins / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D003064:Cnidarian Venoms; D003603:Cytotoxins; D013301:Streptolysins; C025964:streptolysin O; C012307:equinatoxin