A template-assembled synthetic protein surface mimetic of the von Willebrand factor A1 domain inhibits botrocetin-induced platelet aggregation.
Platelet adhesion, the initial step of platelet activation, is mediated by the interaction of von Willebrand factor (VWF) with its platelet receptor, the GPIb-IX complex. The binding of VWF to GPIb-IX is induced either by increased shear stress or by exogenous modulators, such as botrocetin. At a molecular level, this interaction takes place between the A1 domain of VWF and the GPIb alpha chain of the GPIb-IX complex. We report here the design and functional characteristics of a VWF template-assembled synthetic protein (TASP), a chimeric four-helix-bundle TASP scaffold mimicking the surface of the A1 domain. Twelve residues located on helices alpha 3 and alpha 4 in the native A1 domain were grafted onto a surface formed by two neighboring helices of the TASP. VWF TASP was found to inhibit specifically botrocetin-induced platelet aggregation and to bind both botrocetin and GPIb alpha. However, in contrast to the native A1 domain, VWF TASP did not bind simultaneously to both ligands. Modeling studies revealed that the relative orientation of the alpha helices in VWF TASP led to a clash of bound botrocetin and GPIb alpha. These results demonstrate that a chimeric four-helix-bundle TASP as a scaffold offers a suitable surface for presenting crucial residues of the VWF A1 domain; the potential of the TASP approach for de novo protein design and mimicry is thereby illustrated.
Hauert
Jacques
J
Hematology Service, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
Fernandez-Carneado
Jimena
J
Michielin
Olivier
O
Mathieu
Stéphane
S
Grell
Daniel
D
Schapira
Marc
M
Spertini
Olivier
O
Mutter
Manfred
M
Tuchscherer
Gabriele
G
Kovacsovics
Tibor
T
D001665:Binding Sites; D040761:Biomimetic Materials / Q000737:chemistry*; D002942:Circular Dichroism; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D006801:Humans; D008958:Models, Molecular; D010973:Platelet Adhesiveness / Q000502:physiology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism; D015202:Protein Engineering; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D013698:Templates, Genetic; D014841:von Willebrand Factor / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*
D003435:Crotalid Venoms; D010975:Platelet Aggregation Inhibitors; D019038:Platelet Glycoprotein GPIb-IX Complex; D014841:von Willebrand Factor; C030961:botrocetin; D017479:Receptors, Platelet-Derived Growth Factor