Model of a ternary complex between activated factor VII, tissue factor and factor IX

Thromb Haemost. 2002 Jul;88(1):74-82.

Abstract

Upon binding to tissue factor, FVIIa triggers coagulation by activating vitamin K-dependent zymogens, factor IX (FIX) and factor X (FX). To understand recognition mechanisms in the initiation step of the coagulation cascade, we present a three-dimensional model of the ternary complex between FVIIa:TF:FIX. This model was built using a full-space search algorithm in combination with computational graphics. With the known crystallographic complex FVIIa:TF kept fixed, the FIX docking was performed first with FIX Gla-EGF1 domains, followed by the FIX protease/EGF2 domains. Because the FIXa crystal structure lacks electron density for the Gla domain, we constructed a chimeric FIX molecule that contains the Gla-EGF1 domains of FVIIa and the EGF2-protease domains of FIXa. The FVIIa:TF:FIX complex has been extensively challenged against experimental data including site-directed mutagenesis, inhibitory peptide data, haemophilia B database mutations, inhibitor antibodies and a novel exosite binding inhibitor peptide. This FVIIa:TF:FIX complex provides a powerful tool to study the regulation of FVIIa production and presents new avenues for developing therapeutic inhibitory compounds of FVIIa:TF:substrate complex.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Algorithms
  • Binding Sites
  • Blood Coagulation Factors / chemistry*
  • Blood Coagulation Factors / metabolism*
  • Computer Simulation
  • Factor IX / chemistry
  • Factor IX / metabolism
  • Factor VIIa / chemistry
  • Factor VIIa / metabolism
  • Humans
  • Models, Molecular*
  • Protein Binding
  • Protein Structure, Tertiary
  • Sequence Alignment
  • Thromboplastin / chemistry
  • Thromboplastin / metabolism

Substances

  • Blood Coagulation Factors
  • Factor IX
  • Thromboplastin
  • Factor VIIa