title: Plasmodium falciparum: effects of membrane modulating agents on direct binding of rhoptry proteins to human erythrocytes.
abstract: We studied the effects of membrane modulation on the interaction of Plasmodium falciparum rhoptry proteins of 140/130/110 kDa (Rhop-H) with human and mouse erythrocytes. Cells treated with 2-(2-methoxyethoxy)ethyl-8-(cis-2-n-octylcyclopropyl)octanoate, myristoleyl alcohol, and proteins extracted with sublytic concentrations of membrane solubilizing detergents were used in erythrocyte binding assays. Protein binding was evaluated by immunoblotting using Rhop-H- and SERA-specific antisera, 1B9, K15, and 5E3, respectively. Protein binding to liposomes prepared with dipalmitoyl-L-alpha-phosphatidylcholine (DPPC) or dilauroyl-L-alpha-phosphatidylcholine (DLPC) was also examined. Our results show that erythrocyte membrane modulation markedly enhanced direct Rhop-H binding to intact human erythrocytes. Binding of SERA to intact human erythrocytes appeared unaffected. Both DPPC and DLPC liposomes had similar Rhop-H and SERA protein binding activities. However, binding to DLPC liposomes was reduced. Rhop-H and SERA extracted with the detergents octanoyl-N-methylglucamide, decanoyl-N-methylglucamide, sodium deoxycholate, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate bound directly to intact human erythrocytes, probably by partitioning hydrophobically into the membranes. Sodium carbonate treatment demonstrated a nonintegral association of Rhop-H with the erythrocyte membrane during invasion. Membrane modulation may expose cryptic phospholipid binding sites in the bilayer.
authors.affiliation: Department of Biology, Cleveland State University, Ohio 44115, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Ndengele
authors.forename: D G
authors.initials: DG
authors.lastname: Messineo
authors.forename: T
authors.initials: T
authors.lastname: Sam-Yellowe
authors.forename: J A
authors.initials: JA
authors.lastname: Harwalkar
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000494:pharmacology; D000953:Antigens, Protozoan / Q000378:metabolism*; D003902:Detergents / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000378:metabolism*; D005233:Fatty Alcohols / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D008081:Liposomes / Q000378:metabolism; D051379:Mice; D009439:Neuraminidase / Q000494:pharmacology; D010963:Plasmodium falciparum / Q000276:immunology*; D011485:Protein Binding / Q000187:drug effects; D015800:Protozoan Proteins / Q000378:metabolism*; D013228:Stearates / Q000494:pharmacology; D013347:Subcellular Fractions / Q000378:metabolism; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D003902:Detergents; D005233:Fatty Alcohols; D008081:Liposomes; D015800:Protozoan Proteins; D013228:Stearates; C057495:serine repeat antigen, Plasmodium; C018672:9,10-tetradecenol; C023714:A(2)C; D009439:Neuraminidase; D014357:Trypsin