Aegyptin, a novel mosquito salivary gland protein, specifically binds to collagen and prevents its interaction with platelet glycoprotein VI, integrin alpha2beta1, and von Willebrand factor.
Blood-sucking arthropods have evolved a number of inhibitors of platelet aggregation and blood coagulation. In this study we have molecularly and functionally characterized aegyptin, a member of the family of 30-kDa salivary allergens from Aedes aegypti, whose function remained elusive thus far. Aegyptin displays a unique sequence characterized by glycine, glutamic acid, and aspartic acid repeats and was shown to specifically block collagen-induced human platelet aggregation and granule secretion. Plasmon resonance experiments demonstrate that aegyptin binds to collagen types I-V (K(d) approximately 1 nm) but does not interact with vitronectin, fibronectin, laminin, fibrinogen, and von Willebrand factor (vWf). In addition, aegyptin attenuates platelet adhesion to soluble or fibrillar collagen. Furthermore, aegyptin inhibits vWf interaction with collagen type III under static conditions and completely blocks platelet adhesion to collagen under flow conditions at high shear rates. Notably, aegyptin prevents collagen but not convulxin binding to recombinant glycoprotein VI. These findings suggest that aegyptin recognizes specific binding sites for glycoprotein VI, integrin alpha2beta1, and vWf, thereby preventing collagen interaction with its three major ligands. Aegyptin is a novel tool to study collagen-platelet interaction and a prototype for development of molecules with antithrombotic properties.
Calvo
Eric
E
Vector Biology Section, Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Bethesda, Maryland 20892-8132.
Tokumasu
Fuyuki
F
Biochemical and Biophysical Parasitology Section, Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Bethesda, Maryland 20892-8132.
Marinotti
Osvaldo
O
Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900.
Villeval
Jean-Luc
JL
INSERM, U790, Université Paris XI, Institut Gustave Roussy, 94805 Villejuif, France.
Ribeiro
José M C
JMC
Vector Biology Section, Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Bethesda, Maryland 20892-8132.
Francischetti
Ivo M B
IMB
Vector Biology Section, Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Bethesda, Maryland 20892-8132. Electronic address: ifrancischetti@niaid.nih.gov.
D000330:Aedes / Q000502:physiology*; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000502:physiology*; D003094:Collagen / Q000378:metabolism*; D019476:Insect Proteins / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D038982:Integrin alpha2beta1 / Q000378:metabolism*; D010974:Platelet Aggregation; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism*; D012471:Salivary Proteins and Peptides / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D013816:Thermodynamics; D014841:von Willebrand Factor / Q000378:metabolism*
D002352:Carrier Proteins; D019476:Insect Proteins; D038982:Integrin alpha2beta1; D010980:Platelet Membrane Glycoproteins; D012471:Salivary Proteins and Peptides; C583517:aegyptin protein, Aedes aegypti; C098341:platelet membrane glycoprotein VI; D014841:von Willebrand Factor; D003094:Collagen