Senior Project Advisor
P. Clint Spiegel
factor VIII, blood coagulation, x-ray crystallography, antibody inhibitors, antibody binding
Factor VIII (fVIII) is a procoagulant protein that binds to activated factor IX (fIXa) on platelet surfaces to form the intrinsic tenase complex. Due to the high immunogenicity of fVIII, generation of antibody inhibitors is a common occurrence in patients during hemophilia A treatment and spontaneously occurs in acquired hemophilia A patients. Non-classical antibody inhibitors, which block fVIII activation by thrombin and formation of the tenase complex, are the most common anti-C2 domain pathogenic inhibitors in hemophilia A murine models and have been identified in patient plasmas. In this study, we report on the X-ray crystal structure of a B domain-deleted bioengineered fVIII bound to the non classical antibody inhibitor, G99. While binding to G99 does not disrupt the overall domain architecture of fVIII, the C2 domain undergoes an ~8 Å translocation that is concomitant with breaking multiple domain-domain interactions. Analysis of normalized B-factor values revealed several solvent-exposed loops in the C1 and C2 domains which experience a decrease in thermal motion in the presence of inhibitory antibodies. Our results enhance our understanding on the structural nature of binding non-classical inhibitors and provide a structural dynamics-based rationale for cooperativity between anti-C domain inhibitors.
Ronayne, Estelle K.; Peters, Shaun C.; Gish, Joseph; Wilson, Celena; Spencer, H Trent; Doering, Christopher B.; Lollar, Pete; Spiegel, P Clint Jr.; and Childers, Kenneth C., "Structure of Blood Coagulation Factor VIII in Complex with Anti-C2 Domain Inhibitory Antibody" (2021). WWU Honors Program Senior Projects. 487.
Subjects - Topical (LCSH)
Blood coagulation factor VIII antibodies; Hemophilia
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