Structure of Blood Coagulation Factor VIII in Complex With an Anti-C2 Domain Non-Classical, Pathogenic Antibody Inhibitor

• Type of Material: Article
• Authors: Estelle K Ronayne, Western Washington University; Shuan C Peters, Western Washington University; Joseph S Gish, Western Washington University; Celena Wilson, Western Washington University; H Trent Spencer, Emory University; Christopher Doering, Emory University; John Lollar, Emory University; Clint P Spiegel, Western Washington University; Kenneth C Childers, Western Washington University
• Language: English
• Date: 2021-06-10
• Publisher: FRONTIERS MEDIA SA
• Publication Version: Final Published Version
• Copyright Statement: © 2021 Ronayne, Peters, Gish, Wilson, Spencer, Doering, Lollar, Spiegel and Childers
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3389/fimmu.2021.697602
• Title of Journal or Parent Work: FRONTIERS IN IMMUNOLOGY
• Volume: 12
• Start Page: 697602
• End Page: 697602
• Grant/Funding Information: The Berkeley Center for Structural Biology is supported in part by the National Institutes of Health, National Institute of General Medical Sciences, and the Howard Hughes Medical Institute.; The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.; This Work Was Supported by the Dreyfus Foundation (Henry Dreyfus Teacher-Scholar Award), the National Science Foundation (MRI 1429164) and the National Institutes of Health/National Heart, Lung and Blood Institute (Award Numbers R15HL103518 and U54HL141981 to PS, Award Numbers R44HL117511, R44HL110448, U54HL112309 and U54HL141981 to CD, HS and PL).; The Pilatus detector on 5.0.1. was funded under NIH grant S10OD021832.; The ALS-ENABLE beamlines are supported in part by the National Institutes of Health, National Institute of General Medical Sciences, Grant P30 GM124169.
• Keywords: blood coagulation; x-ray crystallography; DIVERSITY; Science & Technology; C2 DOMAIN; C1 DOMAIN; HEMOPHILIA-A; TERNARY COMPLEX; CELL EPITOPE; BINDING; MUTATIONS; antibody binding; antibody inhibitors; Life Sciences & Biomedicine; Immunology; IDENTIFICATION; factor VIII; SURFACE
• Research Categories: Chemistry, General

Abstract

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. These results enhance our understanding on the structural nature of binding non-classical inhibitors and provide a structural dynamics-based rationale for cooperativity between anti-C1 and anti-C2 domain inhibitors.