Platelet-type von Willebrand disease: Local disorder of the platelet GPIbα ß-switch drives high-affinity binding to von Willebrand factor.
J Thromb Haemost
; 17(12): 2022-2034, 2019 12.
Article
em En
| MEDLINE
| ID: mdl-31448872
ABSTRACT
BACKGROUND:
Mutations in the ß-switch of GPIbα cause gain-of-function in the platelet-type von Willebrand disease. Structures of free and A1-bound GPIbα suggest that the ß-switch undergoes a conformational change from a coil to a ß-hairpin.OBJECTIVES:
Platelet-type von Willebrand disease (VWD) mutations have been proposed to stabilize the ß-switch by shifting the equilibrium in favor of the ß-hairpin, a hypothesis predicated on the assumption that the complex crystal structure between A1 and GPIbα is the high-affinity state.METHODS:
Hydrogen-deuterium exchange mass spectrometry is employed to test this hypothesis using G233V, M239V, G233V/M239V, W230L, and D235Y disease variants of GPIbα. If true, the expectation is a decrease in hydrogen-deuterium exchange within the ß-switch as a result of newly formed hydrogen bonds between the ß-strands of the ß-hairpin.RESULTS:
Hydrogen-exchange is enhanced, indicating that the ß-switch favors the disordered loop conformation. Hydrogen-exchange is corroborated by differential scanning calorimetry, which confirms that these mutations destabilize GPIbα by allowing the ß-switch to dissociate from the leucine-rich-repeat (LRR) domain. The stability of GPIbα and its A1 binding affinity, determined by surface plasmon resonance, are correlated to the extent of hydrogen exchange in the ß-switch.CONCLUSION:
These studies demonstrate that GPIbα with a disordered loop is binding-competent and support a mechanism in which local disorder in the ß-switch exposes the LRR-domain of GPIbα enabling high-affinity interactions with the A1 domain.Palavras-chave
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Base de dados:
MEDLINE
Assunto principal:
Doenças de von Willebrand
/
Plaquetas
/
Fator de von Willebrand
/
Complexo Glicoproteico GPIb-IX de Plaquetas
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article