Thromb Haemost 2004; 91(01): 16-27
DOI: 10.1160/TH03-04-0222
Blood Coagulation, Fibrinolysis and Cellular Haemostasis
Schattauer GmbH

The factor V C1 domain is involved in membrane binding: identification of functionally important amino acid residues within the C1 domain of factor V using alanine scanning mutagenesis

Authors

  • Mahasen Saleh*

    1   Division of Hematology, Departments of Medicine and Pathology, Duke University Medical Center, Durham, North Carolina, USA
    3   Current address: King Faisal Hospital and Research Center, Riyadh, Saudi Arabia
  • Weimin Peng*

    1   Division of Hematology, Departments of Medicine and Pathology, Duke University Medical Center, Durham, North Carolina, USA
  • Mary Ann Quinn-Allen

    1   Division of Hematology, Departments of Medicine and Pathology, Duke University Medical Center, Durham, North Carolina, USA
  • Sandra Macedo-Ribeiro

    2   Max-Planck-Institut fur Biochemie, Abteilung Strukturforschung, Martinsried, Germany
    4   Current address: Centro de Neurociências de Coimbra, Coimbra, Portugal
  • Pablo Fuentes-Prior

    2   Max-Planck-Institut fur Biochemie, Abteilung Strukturforschung, Martinsried, Germany
  • Wolfram Bode

    2   Max-Planck-Institut fur Biochemie, Abteilung Strukturforschung, Martinsried, Germany
  • William H. Kane

    1   Division of Hematology, Departments of Medicine and Pathology, Duke University Medical Center, Durham, North Carolina, USA
Further Information

Publication History

Received 10 April 2003

Accepted after resubmission 07 October 2003

Publication Date:
30 November 2017 (online)

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Summary

The contribution of the factor Va C1 domain (fVa-C1) to assembly of the prothrombinase complex has not been previously investigated. The homologous fVa-C2 domain contains a binding site for phosphatidylserine (PS) that includes the indole moieties of Trp2063/Trp2064 at the apex of spike-1. In order to investigate the structure and function of fVa-C1 a molecular model was constructed based on the structure of fVa-C2. The aromatic and hydrophobic side chains of Tyr1956/Leu1957 in fVaC1 are located at the predicted apex of spike-3. Exposed charged and hydrophobic residues in fVa-C1 were changed to alanine in clusters of 1-3 mutations per construct. The resultant 20 mutants were expressed in COS cells and screened for binding to immobilized PS and prothrombinase activity on phospholipid vesicles containing either 25% or 5% PS. Two mutants, (Y1956,L1957)A, and (R2023,R2027)A showed both decreased binding to immobilized PS and a selective decrease in prothrombinase activity on membranes containing 5% PS. The interaction of purified (Y1956,L1957)A with phospholipid vesicles was studied using fluorescence resonance energy transfer and prothrombinase assays. The affinity of (Y1956,L1957)A binding to 25% PS membranes was reduced 12-fold compared to rHFVa. Prothrombin activation in the presence of (Y1956,L1957)A was markedly impaired on phospholipid vesicles containing 10% or less PS. We conclude that solvent exposed hydrophobic and aromatic amino acids in both fVa-C1 and fVa-C2 contribute to the interaction of factor V with PS membranes.

* Both authors contributed equally to this work.