title: A template-assembled synthetic protein surface mimetic of the von Willebrand factor A1 domain inhibits botrocetin-induced platelet aggregation.
abstract: 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.
authors.affiliation: Hematology Service, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland.
authors.forename: Jacques
authors.initials: J
authors.lastname: Hauert
authors.forename: Jimena
authors.initials: J
authors.lastname: Fernandez-Carneado
authors.forename: Olivier
authors.initials: O
authors.lastname: Michielin
authors.forename: Stéphane
authors.initials: S
authors.lastname: Mathieu
authors.forename: Daniel
authors.initials: D
authors.lastname: Grell
authors.forename: Marc
authors.initials: M
authors.lastname: Schapira
authors.forename: Olivier
authors.initials: O
authors.lastname: Spertini
authors.forename: Manfred
authors.initials: M
authors.lastname: Mutter
authors.forename: Gabriele
authors.initials: G
authors.lastname: Tuchscherer
authors.forename: Tibor
authors.initials: T
authors.lastname: Kovacsovics
mesh_terms: 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*
chemical_list: 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