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Structural basis for hemophilia A caused by mutations in the C domains of blood coagulation factor VIII
A J Gale1, J L Pellequer, E D Getzoff
1Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
Insights
Three dimensional models of factor VIII (FVIII) C domains reveal structural insights into hemophilia A. Most mutations disrupting FVIII structure explain disease, with few impacting interactions with other factors.
Area of Science:
- Biochemistry
- Structural Biology
- Genetics
Background:
- Factor VIII (FVIII) deficiency causes hemophilia A.
- Missense mutations in FVIII C domains are linked to disease.
- Understanding the structural impact of these mutations is crucial.
Purpose of the Study:
- To generate 3D homology models of FVIII C1 and C2 domains.
- To investigate the structural basis of FVIII deficiency caused by C domain mutations.
- To categorize mutations based on their structural and functional effects.
Main Methods:
- Three-dimensional homology modeling of FVIII C1 and C2 domains.
- Analysis of >250 missense mutations causing FVIII deficiency.
- Classification of mutated residues based on conservation and location (buried/exposed).
Main Results:
- FVIII C1 and C2 domains form beta-sandwich structures, linked head-to-head.
- 34 missense mutations within the C domains were analyzed.
- Mutations were categorized into conserved/non-conserved and buried/exposed residues.
- Most mutations disrupt FVIII structure; only a few may affect intermolecular interactions.
Conclusions:
- The study provides a structural rationale for 34 missense mutations in FVIII C domains.
- Predictable disruptions in FVIII structure explain the pathogenicity of most mutations.
- A small subset of mutations might directly impact interactions with other coagulation factors or von Willebrand factor.
Abstract:
Three dimensional homology models for the C1 and C2 domains of factor VIII (FVIII) were generated. Each C domain formed a beta-sandwich, and C1 was covalently connected to C2 in a head-to-head orientation. Of the >250 missense mutations that cause FVIII deficiency and hemophilia A, 34 are in the C domains. We used the FVIII C1-C2 model to infer the structural basis for the pathologic effects of these mutations. The mutated residues were divided into four categories: 15 conserved buried residues that affect normal packing of the hydrophobic side chains, 2 non-conserved buried residues that affect structure, 11 conserved exposed residues and 6 non-conserved exposed residues. The effects of all 34 missense mutations can be rationalized by predictable disruptions of FVIII structure while at most four mutations (S2069F, T2154I, R2209Q/G/L and E2181D) may affect residues directly involved in intermolecular interactions of FVIII/VIIIa with other coagulation factors or vWF.