title: Modifications in erythrocyte membrane zeta potential by Plasmodium falciparum infection.
abstract: The zeta potential (ZP) is an electrochemical property of cell surfaces that is determined by the net electrical charge of molecules exposed at the surface of cell membranes. Membrane proteins contribute to the total net electrical charge of cell surfaces and can alter ZP through variation in their copy number and changes in their intermolecular interactions. Plasmodium falciparum extensively remodels its host red blood cell (RBC) membrane by placing 'knob'-like structures at the cell surface. Using an electrophoretic mobility assay, we found that the mean ZP of human RBCs was -15.7 mV. In RBCs infected with P. falciparum trophozoites ('iRBCs'), the mean ZP was significantly lower (-14.6 mV, p<0.001). Removal of sialic acid from the cell surface by neuraminidase treatment significantly decreased the ZP of both RBCs (-6.06 mV) and iRBCs (-4.64 mV). Parasite-induced changes in ZP varied by P. falciparum clone and the presence of knobs on the iRBC surface. Variations in ZP values were accompanied by altered binding of iRBCs to human microvascular endothelial cells (MVECs). These data suggest that parasite-derived knob proteins contribute to the ZP of iRBCs, and that electrostatic and hydrophobic interactions between iRBC and MVEC membranes are involved in cytoadherence.
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-8132, USA. ftokumasu@niaid.nih.gov
authors.forename: Fuyuki
authors.initials: F
authors.lastname: Tokumasu
authors.forename: Graciela R
authors.initials: GR
authors.lastname: Ostera
authors.forename: Chanaki
authors.initials: C
authors.lastname: Amaratunga
authors.forename: Rick M
authors.initials: RM
authors.lastname: Fairhurst
mesh_terms: D002448:Cell Adhesion; D024202:Electrophoretic Mobility Shift Assay; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology; D004910:Erythrocyte Membrane / Q000469:parasitology / Q000502:physiology* / Q000648:ultrastructure; D004912:Erythrocytes / Q000166:cytology / Q000469:parasitology* / Q000648:ultrastructure; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008564:Membrane Potentials / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009439:Neuraminidase / Q000378:metabolism; D010455:Peptides / Q000502:physiology*; D010963:Plasmodium falciparum / Q000502:physiology*; D015800:Protozoan Proteins / Q000502:physiology*; D055672:Static Electricity; D014357:Trypsin / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D010455:Peptides; D015800:Protozoan Proteins; C042968:knob protein, Plasmodium falciparum; D009439:Neuraminidase; D014357:Trypsin; D019158:N-Acetylneuraminic Acid