Template-Assembled Synthetic Protein Surface Mimetic of the von Willebrand Factor A1 domain Inhibits Botrocetin-Induced Platelet Aggregation

• Published in: Chembiochem : a European journal of chemical biology 2004-06, Vol.5 (6), p.856-864
• Main Authors: Hauert, Jacques, Fernandez-Carneado, Jimena, Michielin, Olivier, Mathieu, Stéphane, Grell, Daniel, Schapira, Marc, Spertini, Olivier, Mutter, Manfred, Tuchscherer, Gabriele, Kovacsovics, Tibor
• Format: Article
• Language: English
• Subjects: Binding Sites; Biomimetic Materials - chemistry; botrocetin; Circular Dichroism; Crotalid Venoms - antagonists & inhibitors; Crotalid Venoms - pharmacology; Humans; Models, Molecular; molecular modeling; Platelet Adhesiveness - physiology; Platelet Aggregation Inhibitors - pharmacology; Platelet Glycoprotein GPIb-IX Complex - metabolism; protein design; Protein Engineering; Receptors, Platelet-Derived Growth Factor - metabolism; template synthesis; Templates, Genetic; von Willebrand factor; von Willebrand Factor - chemistry; von Willebrand Factor - genetics; von Willebrand Factor - pharmacology
• ISSN: 1439-4227; 1439-7633
• DOI: 10.1002/cbic.200300826

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 GPIbα 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 α3 and α4 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 GPIbα. 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 α helices in VWF TASP led to a clash of bound botrocetin and GPIbα. 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. Inhibition all bundled up: A four‐helix‐bundle template‐assembled synthetic protein (TASP) mimicking the surface of the A1 domain of von Willebrand factor (VWF) was designed (see picture). VWF TASP inhibited botrocetin‐induced platelet aggregation and bound two VWF ligands, botrocetin and GPIbα, thereby illustrating the potential of the TASP approach for de novo protein design and mimicry.