Plasmodium falciparum: effects of membrane modulating agents on direct binding of rhoptry proteins to human erythrocytes

Exp Parasitol. 1995 Sep;81(2):191-201. doi: 10.1006/expr.1995.1108.

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.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antibodies, Protozoan / pharmacology
  • Antigens, Protozoan / metabolism*
  • Detergents / pharmacology
  • Erythrocyte Membrane / metabolism*
  • Fatty Alcohols / pharmacology
  • Humans
  • Immunoblotting
  • Liposomes / metabolism
  • Mice
  • Neuraminidase / pharmacology
  • Plasmodium falciparum / immunology*
  • Protein Binding / drug effects
  • Protozoan Proteins / metabolism*
  • Stearates / pharmacology
  • Subcellular Fractions / metabolism
  • Trypsin / pharmacology

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Detergents
  • Fatty Alcohols
  • Liposomes
  • Protozoan Proteins
  • Stearates
  • serine repeat antigen, Plasmodium
  • 9,10-tetradecenol
  • A(2)C
  • Neuraminidase
  • Trypsin