title: Von Willebrand factor-A1 domain binds platelet glycoprotein Ibα in multiple states with distinctive force-dependent dissociation kinetics.
abstract: Circulating von Willebrand factor (VWF) adopts a closed conformation that shields the platelet glycoprotein Ibα (GPIbα) binding site in the VWF-A1 domain. Immobilized at sites of vascular injury, VWF is activated by its interaction with collagen and the exertion of increased hemodynamic forces. Studies on native VWF strings and isolated A1 domains suggest the existence of multiple A1 binding states in different biophysical contexts. In this single-molecule study, we have used a biomembrane force probe (BFP) and a flow chamber to identify and characterize a collagen binding induced conformation with a higher affinity to platelet GPIbα. As force increases, our results show that collagen binding increases the stability of GPIbα bond with both VWF and isolated A1 domain. However, the collagen 2D binding affinity for VWF-A3 domain is 10 times of that for A1 domain, suggesting the initial VWF capture is mediated by A3-collagen interaction while A1-collagen regulates the subsequent VWF activation. Our results reveal the molecular mechanism of collagen-regulated, A1-mediated platelet adhesion enhancement. Characterization of different A1 states provides insights into binding heterogeneity of VWF in different scenarios of inflammation and thrombosis.
authors.affiliation: Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA; Heart Research Institute, Newtown, NSW 2042, Australia; Charles Perkins Centre, Camperdown, NSW 2006, Australia.
authors.forename: Lining
authors.initials: L
authors.lastname: Ju
authors.affiliation: Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Fangyuan
authors.initials: F
authors.lastname: Zhou
authors.affiliation: School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Hang
authors.initials: H
authors.lastname: Lu
authors.affiliation: Cardiovascular Research Section, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Cruz
authors.affiliation: Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA; Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA 30332, USA. Electronic address: arnold.ju@sydney.edu.au.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhu
mesh_terms: D001665:Binding Sites; D001792:Blood Platelets; D002478:Cells, Cultured; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D010973:Platelet Adhesiveness / Q000502:physiology*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013314:Stress, Mechanical
chemical_list: D016326:Extracellular Matrix Proteins; D019038:Platelet Glycoprotein GPIb-IX Complex; C460760:VWA1 protein, human; C094990:adhesion receptor; D003094:Collagen
keywords: Glycoprotein Ibα; Microfluidics; Platelets; Single bond; von Willebrand factor