PB0801 - Conformational dynamics of plasma-derived von Willebrand factor recapitulate isolated A1 domain and autoinhibitory module

Monday, July 11, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Emily R. Legan

Graduate Student
Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, USA
Atlanta, Georgia, United States

Co-Author(s)

MW

Moriah S. Wilson

Research Specialist
Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine
Atlanta, Georgia, United States
NA

Nicholas A. Arce

Graduate Student
Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, USA
Atlanta, Georgia, United States
EP

Ernest T. Parker

Research Specialist Supervisor
Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine
Atlanta, Georgia, United States
PL

Pete Lollar

Professor of Pediatrics
Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine
Atlanta, Georgia, United States
Renhao Li, PhD

Professor of Pediatrics
Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine
Atlanta, Georgia, United States

Background: Our lab has recently provided detailed characterizations of the autoinhibitory module (AIM), the discontinuous flanking regions that cooperatively shield the A1 domain and regulate its binding to cognate platelet receptor glycoprotein (GP) Ibα. While our recent analyses have described the mechanical and biochemical properties of AIM-A1 as an independent functional unit, the impact of the neighboring D’D3 and A2 domains on AIM dynamics remain unclear.

Aims: We aim to evaluate whether adjacent domains to the VWF A1 domain impact protection of the GPIbα binding site through further stabilization of the autoinhibitory module.

Methods: Conformational dynamics of purified plasma-derived VWF were compared to purified mammalian-derived protein fragments with the A1 domain using hydrogen-deuterium exchange mass spectrometry.

Results: AIM-A1 has slightly faster rates of HDX in both regions of the AIM compared to longer VWF fragments and pdVWF as well as the secondary GPIbα binding site proximal to residue Arg1341, which we have previously shown to form a complex with the N-terminal AIM through X-ray crystallography. Additionally, we observe similar HDX rates and relative fractional uptake of deuterium in the secondary GPIbα binding sites, suggesting that additional protection of the GPIbα binding sites is not conferred through the D’D3 or A2 domains.

Conclusion(s): These data suggest that adjacent D’D3 and A2 domains marginally alter the conformational dynamics of the AIM in solution, likely by constraining flexibility of the module. Nonetheless, regulation of AIM function appears to be primarily influenced by local AIM-A1 dynamics.