6NAN

NMR structure determination of Ixolaris and Factor X interaction reveals a noncanonical mechanism of Kunitz inhibition


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

NMR structure determination of Ixolaris and factor X(a) interaction reveals a noncanonical mechanism of Kunitz inhibition.

De Paula, V.S.Sgourakis, N.G.Francischetti, I.M.B.Almeida, F.C.L.Monteiro, R.Q.Valente, A.P.

(2019) Blood 134: 699-708

  • DOI: 10.1182/blood.2018889493
  • Primary Citation of Related Structures:  
    6NAN

  • PubMed Abstract: 
  • 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 signal ...

    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.


    Related Citations: 
    • Recombinant expression of Ixolaris, a Kunitz-type inhibitor from the tick salivary gland, for NMR studies.
      De Paula, V.S., Silva, F.H.S., Francischetti, I.M.B., Monteiro, R.Q., Valente, A.P.
      (2017) Protein Expr Purif 139: 49

    Organizational Affiliation

    Instituto de Bioquímica Médica, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Brazil; and.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
IxolarisA140Ixodes scapularisMutation(s): 0 
Find proteins for Q964Q0 (Ixodes scapularis)
Explore Q964Q0 
Go to UniProtKB:  Q964Q0
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 100 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the lowest energy 
  • OLDERADO: 6NAN Olderado

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2019-06-12
    Type: Initial release
  • Version 1.1: 2019-09-04
    Changes: Data collection, Database references