Plasmodium falciparum uses a key functional site in complement receptor type-1 for invasion of human erythrocytes

Blood. 2011 Aug 18;118(7):1923-33. doi: 10.1182/blood-2011-03-341305. Epub 2011 Jun 17.

Abstract

The Plasmodium falciparum adhesin PfRh4 binds to complement receptor type-1 (CR1) on human erythrocytes and mediates a glycophorin-independent invasion pathway. CR1 is a complement regulator and immune-adherence receptor on erythrocytes required for shuttling of C3b/C4b-opsonized particles to liver and spleen for phagocytosis. Using recombinant CR1 constructs, we mapped the recognition site for PfRh4 to complement control protein modules 1 to 3 (CCP1-3) at the membrane-distal amino terminus of CR1. This region of CR1 binds to C4b and C3b and accelerates decay of both classic pathway and alternative pathway C3 and C5 convertases. CCP1-3 competed for PfRh4 binding to erythroid CR1 and inhibited the PfRh4-CR1 invasion pathways across a wide range of P falciparum strains. PfRh4 did not bind significantly to other CR1 constructs, including CCP15-17, which is 85% identical to CCP1-3. PfRh4 binding to CR1 did not affect its C3b/C4b binding capability, and we show evidence for a ternary complex between CCP1-3, C4b, and PfRh4. PfRh4 binding specifically inhibited CR1's convertase decay-accelerating activity, whereas there was no effect on factor H-mediated decay-accelerating activity. These results increase our understanding of the functional implications of CR1 engagement with PfRh4 and highlight the interplay between complement regulation and infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Erythrocytes / parasitology*
  • Host-Parasite Interactions*
  • Humans
  • Malaria, Falciparum / parasitology*
  • Membrane Proteins / metabolism*
  • Plasmodium falciparum / physiology*
  • Protein Binding
  • Protozoan Proteins / metabolism*
  • Receptors, Complement / metabolism*
  • Recombinant Proteins / metabolism

Substances

  • Membrane Proteins
  • Protozoan Proteins
  • RH4 protein, Plasmodium falciparum
  • Receptors, Complement
  • Recombinant Proteins