The N-terminal autoinhibitory module of the A1 domain in von Willebrand factor stabilizes the mechanosensor catch bond.
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ABSTRACT: The von Willebrand factor (VWF), by interacting with the circulatory system and platelets, harnesses hemodynamic forces to form hemostatic plugs or occlusive thrombi. The autoinhibitory modules (AIMs) flanking the VWF-A1 domain were found to contribute to its biomechanical activation. However, how AIM sequences regulate the VWF-A1 binding behavior is controversial and incompletely understood as their structures are currently unsolvable by crystallography. To address this, we first performed molecular dynamics simulations to predict the N-terminal AIM (N-AIM; residues Q1238-E1260) structure. Excitingly, we found that N-AIM could cooperate with C-AIM to form a joint Rotini-like structure, thereby partially autoinhibiting the VWF-A1-GPIbα interaction. Furthermore, we used biomembrane force probe (BFP) assays to experimentally demonstrate that the VWF-A1 containing long N-AIM sequence (1238-A1) exhibited catch-bond behavior as the force first decelerated (catch) and then accelerated (slip) the dissociation. Conversely, VWF-A1 with short N-AIM (1261-A1) displayed bi-variable behaviors with either catch (1261H-A1) or slip bonds (1261L-A1). Notably, such bi-variable transition happened at low temperatures or high pH levels, whereas Q1238-E1260 stabilized the 1238-A1 catch bond regardless of the environmental factors. The physiological study was complemented by platelet perfusion assays using microfluidics. Taken together, these studies provide new mechanobiology on how N-AIM serves as a mechano-regulator of VWF activity, which inspires future VWF-A1 dependent antithrombotic approaches.
SUBMITTER: Zhao YC
PROVIDER: S-EPMC9175105 | biostudies-literature |
REPOSITORIES: biostudies-literature
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