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 1.0 of the entry. See complete history

Literature

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

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

(2019) Blood --: --

  • DOI: 10.1182/blood.2018889493

  • 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 two 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, NMR-derived model reveals a mechanism for an electrostatically guided, high-affinity interaction between Ixolaris and FX heparin-binding (pro)exosite, resulting in 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

    Institute of Medical Biochemistry, Federal University of Rio de Janeiro, Brazil.,NIH, United States.,Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Brazil.,Structural Biology, Federal University of Rio de Janeiro, Brazil valente.anap@gmail.com.,University of California, Santa Cruz, United States.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Ixolaris
A
140Ixodes scapularisMutation(s): 0 
Find proteins for Q964Q0 (Ixodes scapularis)
Go to UniProtKB:  Q964Q0
Experimental Data & Validation

Experimental Data

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

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2019-06-12
    Type: Initial release