Dataset Information

Evidence for the Misfolding of the A1 Domain within Multimeric von Willebrand Factor in Type 2 von Willebrand Disease.

ABSTRACT: Von Willebrand factor (VWF), an exceptionally large multimeric plasma glycoprotein, functions to initiate coagulation by agglutinating platelets in the blood stream to sites of vascular injury. This primary hemostatic function is perturbed in type 2 dysfunctional subtypes of von Willebrand disease (VWD) by mutations that alter the structure and function of the platelet GPIb? adhesive VWF A1 domains. The resulting amino acid substitutions cause local disorder and misfold the native structure of the isolated platelet GPIb?-adhesive A1 domain of VWF in both gain-of-function (type 2B) and loss-of-function (type 2M) phenotypes. These structural effects have not been explicitly observed in A1 domains of VWF multimers native to blood plasma. New mass spectrometry strategies are applied to resolve the structural effects of 2B and 2M mutations in VWF to verify the presence of A1 domain structural disorder in multimeric VWF harboring type 2 VWD mutations. Limited trypsinolysis mass spectrometry (LTMS) and hydrogen-deuterium exchange mass spectrometry (HXMS) are applied to wild-type and VWD variants of the single A1, A2, and A3 domains, an A1A2A3 tridomain fragment of VWF, plasmin-cleaved dimers of VWF, multimeric recombinant VWF, and normal VWF plasma concentrates. Comparatively, these methods show that mutations known to misfold the isolated A1 domain increase the rate of trypsinolysis and the extent of hydrogen-deuterium exchange in local secondary structures of A1 within multimeric VWF. VWD mutation effects are localized to the A1 domain without appreciably affecting the structure and dynamics of other VWF domains. The intrinsic dynamics of A1 observed in recombinant fragments of VWF are conserved in plasma-derived VWF. These studies reveal that structural disorder does occur in VWD variants of the A1 domain within multimeric VWF and provides strong support for VWF misfolding as a result of some, but not all, type 2 VWD variants.

SUBMITTER: Tischer A

PROVIDER: S-EPMC7028320 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Evidence for the Misfolding of the A1 Domain within Multimeric von Willebrand Factor in Type 2 von Willebrand Disease.

Tischer Alexander A Brehm Maria A MA Machha Venkata R VR Moon-Tasson Laurie L Benson Linda M LM Nelton Katelynn J KJ Leger Rachel R RR Obser Tobias T Martinez-Vargas Marina M Whitten Steven T ST Chen Dong D Pruthi Rajiv K RK Bergen H Robert HR Cruz Miguel A MA Schneppenheim Reinhard R Auton Matthew M

Journal of molecular biology 20191017 2

Von Willebrand factor (VWF), an exceptionally large multimeric plasma glycoprotein, functions to initiate coagulation by agglutinating platelets in the blood stream to sites of vascular injury. This primary hemostatic function is perturbed in type 2 dysfunctional subtypes of von Willebrand disease (VWD) by mutations that alter the structure and function of the platelet GPIbα adhesive VWF A1 domains. The resulting amino acid substitutions cause local disorder and misfold the native structure of t ...[more]

PMID: 31628947

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Project description:Essentials The mechanism for the auto-inhibition of von Willebrand factor (VWF) remains unclear. Hydrogen exchange of two VWF A1 fragments with disparate activities was measured and compared. Discontinuous residues flanking A1 form a structural module that blocks A1 binding to the platelet. Our results suggest a potentially unified model of VWF activation. Click to hear an ISTH Academy presentation on the domain architecture of VWF and activation by elongational flow by Dr Springer SUMMARY: Background How von Willebrand factor (VWF) senses and responds to shear flow remains unclear. In the absence of shear flow, VWF or its fragments can be induced to bind spontaneously to platelet GPIb?. Objectives To elucidate the auto-inhibition mechanism of VWF. Methods Hydrogen-deuterium exchange (HDX) of two recombinant VWF fragments expressed from baby hamster kidney cells were measured and compared. Results The shortA1 protein contains VWF residues 1261-1472 and binds GPIb? with a significantly higher affinity than the longA1 protein that contains VWF residues 1238-1472. Both proteins contain the VWF A1 domain (residues 1272-1458). Many residues in longA1, particularly those in the N- and C-terminal sequences flanking the A1 domain, and in helix ?1, loops ?1?2 and ?3?2, demonstrated markedly reduced HDX compared with their counterparts in shortA1. The HDX-protected region in longA1 overlaps with the GPIb?-binding interface and is clustered with type 2B von Willebrand disease (VWD) mutations. Additional comparison with the HDX of denatured longA1 and ristocetin-bound longA1 indicates the N- and C-terminal sequences flanking the A1 domain form cooperatively an integrated autoinhibitory module (AIM) that interacts with the HDX-protected region. Binding of ristocetin to the C-terminal part of the AIM desorbs the AIM from A1 and enables longA1 binding to GPIb?. Conclusion The discontinuous AIM binds the A1 domain and prevents it from binding to GPIb?, which has significant implications for the pathogenesis of type 2B VWD and the shear-induced activation of VWF activity.

Dataset Information

Evidence for the Misfolding of the A1 Domain within Multimeric von Willebrand Factor in Type 2 von Willebrand Disease.

Publications

Evidence for the Misfolding of the A1 Domain within Multimeric von Willebrand Factor in Type 2 von Willebrand Disease.

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