Structure of the DBL3X-DBL4ε region of the VAR2CSA placental malaria vaccine candidate: insight into DBL domain interactions

Sci Rep. 2015 Oct 9:5:14868. doi: 10.1038/srep14868.

Abstract

The human malaria parasite, Plasmodium falciparum, is able to evade spleen-mediated clearing from blood stream by sequestering in peripheral organs. This is due to the adhesive properties conferred by the P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) family exported by the parasite to the surface of infected erythrocytes. Expression of the VAR2CSA variant of PfEMP1 leads to pregnancy-associated malaria, which occurs when infected erythrocytes massively sequester in the placenta by binding to low-sulfated Chondroitin Sulfate A (CSA) present in the intervillous spaces. VAR2CSA is a 350 kDa protein that carries six Duffy-Binding Like (DBL) domains, one Cysteine-rich Inter-Domain Regions (CIDR) and several inter-domain regions. In the present paper, we report for the first time the crystal structure at 2.9 Å of a VAR2CSA double domain, DBL3X-DBL4ε, from the FCR3 strain. DBL3X and DBL4ε share a large contact interface formed by residues that are invariant or highly conserved in VAR2CSA variants, which suggests that these two central DBL domains (DBL3X-DBL4ε) contribute significantly to the structuring of the functional VAR2CSA extracellular region. We have also examined the antigenicity of peptides corresponding to exposed loop regions of the DBL4ε structure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Protozoan / blood
  • Antibodies, Protozoan / immunology
  • Antigens, Protozoan / chemistry
  • Antigens, Protozoan / genetics
  • Antigens, Protozoan / immunology*
  • Binding Sites / genetics
  • Binding Sites / immunology
  • Chondroitin Sulfates / immunology
  • Chondroitin Sulfates / metabolism
  • Crystallography, X-Ray
  • Erythrocytes / immunology
  • Erythrocytes / parasitology
  • Female
  • Host-Parasite Interactions / immunology
  • Humans
  • Immune Sera / immunology
  • Malaria Vaccines / administration & dosage
  • Malaria Vaccines / immunology*
  • Malaria, Falciparum / immunology*
  • Malaria, Falciparum / parasitology
  • Malaria, Falciparum / prevention & control
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Placenta / immunology*
  • Placenta / metabolism
  • Placenta / parasitology
  • Plasmodium falciparum / immunology*
  • Plasmodium falciparum / metabolism
  • Plasmodium falciparum / physiology
  • Pregnancy
  • Protein Binding / immunology
  • Protein Structure, Tertiary
  • Rabbits
  • Sequence Homology, Amino Acid

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Immune Sera
  • Malaria Vaccines
  • VAR2CSA protein, Plasmodium falciparum
  • Chondroitin Sulfates