Electrostatic Steering Enables Flow-Activated Von Willebrand Factor to Bind Platelet Glycoprotein, Revealed by Single-Molecule Stretching and Imaging. Issue 7 (29th March 2019)

• Record Type: Journal Article
• Authors: Jiang, Yan; Fu, Hongxia; Springer, Timothy A.; Wong, Wesley P.
• Is Part Of: Journal of molecular biology. Volume 431:Issue 7(2019)
• Page Start: 1380
• Page End: 1396
• Publication Date: 2019-03-29
• Subjects: VWF von Willebrand factor -- VWD von Willebrand disease -- GPIbα glycoprotein Ibα -- TIRF total internal reflection fluorescence; mechanosensing -- single-molecule fluorescence -- single-molecule force spectroscopy -- hemostasis -- microfluidics; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2019.02.014
• Languages: English
• ISSNs: 0022-2836

Abstract

Abstract: Von Willebrand factor (VWF), a large multimeric blood protein, senses changes in shear stress during bleeding and responds by binding platelets to plug ruptures in the vessel wall. Molecular mechanisms underlying this dynamic process are difficult to uncover using standard approaches due to the challenge of applying mechanical forces while monitoring structure and activity. By combining single-molecule fluorescence imaging with high-pressure, rapidly switching microfluidics, we reveal the key role of electrostatic steering in accelerating the binding between flow-activated VWF and GPIbα, and in rapidly immobilizing platelets under flow. We measure the elongation and tension-dependent activation of individual VWF multimers under a range of ionic strengths and pH levels, and find that the association rate is enhanced by 4 orders of magnitude by electrostatic steering. Under supraphysiologic salt concentrations, strong electrostatic screening dramatically decreases platelet binding to VWF in flow, revealing the critical role of electrostatic attraction in VWF–platelet binding during bleeding. Graphical Abstract: Unlabelled Image Highlights: VWF mechanically senses bleeding and binds platelets to plug ruptures. We stretched and imaged single VWF molecules using a flow-based assay. Electrostatic steering accelerates the binding of receptors to force-activated VWF. Strong electrostatic screening markedly decreases platelet binding to VWF in flow. Electrostatic attraction is critical to VWF–platelet binding in fast flowing blood.