TY - JOUR
T1 - NMR structure determination of Ixolaris and factor X(a) interaction reveals a noncanonical mechanism of Kunitz inhibition
AU - De Paula, Viviane S.
AU - Sgourakis, Nikolaos G.
AU - Francischetti, Ivo M.B.
AU - Almeida, Fabio C.L.
AU - Monteiro, Robson Q.
AU - Valente, Ana Paula
N1 - Funding Information:
This work was supported by grants from Fundacão̧ Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro and Conselho Nacional de Desenvolvimento Cientifí co e Tecnológico. The authors acknowledge the University of California, Santa Cruz Baker cluster for providing access to the computer resources. The authors also thank the facilities of National Center of Nuclear Magnetic Resonance (Federal University of Rio de Janeiro, Rio de Janeiro) for the NMR time.
Funding Information:
This work was supported by grants from Fundacão Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro and Conselho Nacional de Desenvolvimento Cientifi co e Tecnológico. The authors acknowledge the University of California, Santa Cruz Baker cluster for providing access to the computer resources. The authors also thank the facilities of National Center of Nuclear Magnetic Resonance (Federal University of Rio de Janeiro, Rio de Janeiro) for the NMR time.
Publisher Copyright:
Copyright 2011 by The American Society of Hematology; all rights reserved.
PY - 2019/8/22
Y1 - 2019/8/22
N2 - Ixolaris is a potent tick salivary anticoagulant that binds coagulation factor Xa (FXa) and zymogen FX, with formation of a quaternary tissue factor (TF)/FVIIa/ FX(a)/Ixolaris inhibitory complex. Ixolaris blocks TF-induced coagulation and PAR2 signaling and prevents thrombosis, tumor growth, and immune activation. We present a high-resolution structure and dynamics of Ixolaris and describe the structural basis for recognition of FX. Ixolaris consists of 2 Kunitz domains (K1 and K2) in which K2 is strikingly dynamic and encompasses several residues involved in FX binding. This indicates that the backbone plasticity of K2 is critical for Ixolaris biological activity. Notably, a nuclear magnetic resonance–derived model reveals a mechanism for an electrostatically guided, high-affinity interaction between Ixolaris and FX heparin-binding (pro)exosite, resulting in an allosteric switch in the catalytic site. This is the first report revealing the structure-function relationship of an anticoagulant targeting a zymogen serving as a scaffold for TF inhibition.
AB - Ixolaris is a potent tick salivary anticoagulant that binds coagulation factor Xa (FXa) and zymogen FX, with formation of a quaternary tissue factor (TF)/FVIIa/ FX(a)/Ixolaris inhibitory complex. Ixolaris blocks TF-induced coagulation and PAR2 signaling and prevents thrombosis, tumor growth, and immune activation. We present a high-resolution structure and dynamics of Ixolaris and describe the structural basis for recognition of FX. Ixolaris consists of 2 Kunitz domains (K1 and K2) in which K2 is strikingly dynamic and encompasses several residues involved in FX binding. This indicates that the backbone plasticity of K2 is critical for Ixolaris biological activity. Notably, a nuclear magnetic resonance–derived model reveals a mechanism for an electrostatically guided, high-affinity interaction between Ixolaris and FX heparin-binding (pro)exosite, resulting in an allosteric switch in the catalytic site. This is the first report revealing the structure-function relationship of an anticoagulant targeting a zymogen serving as a scaffold for TF inhibition.
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U2 - 10.1182/blood.2018889493
DO - 10.1182/blood.2018889493
M3 - Article
C2 - 31133602
AN - SCOPUS:85071495106
SN - 0006-4971
VL - 134
SP - 699
EP - 708
JO - Blood
JF - Blood
IS - 8
ER -