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.
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.
Garcia
Yesid
Y
Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, CP 020304, BogotA D.C., Colombia, South America.
Puentes
Alvaro
A
Curtidor
Hernando
H
Cifuentes
Gladys
G
Reyes
Claudia
C
Barreto
Jose
J
Moreno
Armando
A
Patarroyo
Manuel E
ME
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000378:metabolism*; D001667:Binding, Competitive; D002918:Chymotrypsin / Q000494:pharmacology; D002942:Circular Dichroism; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism* / Q000469:parasitology; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000494:pharmacology; D010963:Plasmodium falciparum / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D015800:Protozoan Proteins / Q000378:metabolism*; D011869:Radioligand Assay; D017386:Sequence Homology, Amino Acid; D014357:Trypsin / Q000494:pharmacology
D000953:Antigens, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins; C118839:merozoite surface protein 4, Plasmodium; C439571:merozoite surface protein 7, Plasmodium; D009439:Neuraminidase; D002918:Chymotrypsin; D014357:Trypsin