Identifying merozoite surface protein 4 and merozoite surface protein 7 Plasmodium falciparum protein family members specifically binding to human erythrocytes suggests a new malarial parasite-redundant survival mechanism

J Med Chem. 2007 Nov 15;50(23):5665-75. doi: 10.1021/jm070773z. Epub 2007 Oct 18.

Abstract

Plasmodium falciparum merozoite surface proteins (MSP-1 to -11) have been involved in merozoite interaction with the red blood cell (RBC) surface. Peptides covering complete MSP-4 and MSP-7 amino acid sequences were synthesized and tested in RBC binding assays. One MSP-4 high activity binding peptide (HABP) and five MSP-7 HABPs were found having specific binding to RBC surface. MSP-4 and MSP-7 HABP binding was sensitive to enzymatic treatment; they recognized a 52 kDa erythrocyte membrane protein. MSP-4 HABP had low invasion inhibition, suggesting it might bind to RBCs and also be involved in physiological mechanisms, while MSP-7 HABPs displayed different invasion inhibition activity (83-24%) in in vitro tests, suggesting different roles for both proteins during invasion. Structural characteristics found when comparing the MSP-4 HABP with MSP-HABPs displaying epidermal growth factor-like sequences suggested that these redundant MSP-family proteins could be a new parasite strategy for evading host genetic variability and immune pressure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, Protozoan / metabolism*
  • Binding, Competitive
  • Chymotrypsin / pharmacology
  • Circular Dichroism
  • Erythrocytes / drug effects
  • Erythrocytes / metabolism*
  • Erythrocytes / parasitology
  • Humans
  • Membrane Proteins / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Neuraminidase / pharmacology
  • Plasmodium falciparum / metabolism
  • Plasmodium falciparum / physiology*
  • Protein Binding
  • Protozoan Proteins / metabolism*
  • Radioligand Assay
  • Sequence Homology, Amino Acid
  • Trypsin / pharmacology

Substances

  • Antigens, Protozoan
  • Membrane Proteins
  • Protozoan Proteins
  • merozoite surface protein 4, Plasmodium
  • merozoite surface protein 7, Plasmodium
  • Neuraminidase
  • Chymotrypsin
  • Trypsin