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Helical Organization of Blood Coagulation Factor VIII on Lipid Nanotubes
Published on: June 3, 2014
Computational study of coagulation factor VIIa's affinity for phospholipid membranes
Olivier Taboureau1, Ole Hvilsted Olsen
1Haemostasis Biochemistry, Novo Nordisk A/S, Novo Nordisk Park, Building G8.2.90, 2760 Måløv, Denmark.
European Biophysics Journal : EBJ
|November 30, 2006
Summary
Specific mutations in the gamma-carboxyglutamic acid-rich domain of coagulation factor VIIa (FVIIa) enhance its binding to phospholipid membranes, crucial for blood coagulation initiation. These changes improve membrane interaction by altering protein structure and accessibility.
Area of Science:
- Biochemistry
- Molecular Biology
- Computational Biophysics
Background:
- Coagulation factor VIIa (FVIIa), a vitamin-K-dependent enzyme, initiates blood coagulation via interaction with phospholipid membranes.
- Despite structural similarities to other vitamin-K-dependent enzymes, FVIIa's Gla domain exhibits poor affinity for negatively charged phospholipids.
- Specific amino acid differences are hypothesized to cause this reduced membrane affinity.
Purpose of the Study:
- To investigate the molecular basis for the differential binding affinity of FVIIa's Gla domain to phospholipid membranes.
- To model and simulate interactions between wildtype and mutated FVIIa Gla domains with lysophosphatidylserine (lysoPS).
- To elucidate the role of specific mutations (P10Q, K32E) in enhancing membrane interaction.
Main Methods:
- X-ray crystallography data of bovine prothrombin Gla domain-lysoPS complex used for homology modeling.
- Molecular dynamics (MD) simulations to analyze structural and dynamic changes in FVIIa Gla domain-lysoPS complexes.
- Steered molecular dynamics (SMD) simulations to quantify binding affinities by measuring rupture forces.
- Adiabatic mapping to assess the conformational impact of residue insertions on Gla domain structure.
Main Results:
- MD simulations revealed that P10Q and K32E mutations enhance membrane contact by inducing structural changes.
- Mutations facilitate hydrogen bond formation, leading to loop shrinkage and increased phospholipid accessibility.
- SMD simulations provided a ranking of rupture forces for lysoPS dissociation, aiding in understanding phosphatidylserine (PS) interactions.
- Adiabatic mapping confirmed the critical role of residue insertion in modulating Gla domain side chain conformation.
Conclusions:
- The P10Q and K32E mutations significantly improve the membrane-binding affinity of FVIIa's Gla domain.
- Structural rearrangements driven by these mutations are key to enhanced blood coagulation initiation.
- Computational simulations offer valuable insights into the mechanisms of Gla domain-phospholipid interactions.
