6nan

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

Structural highlights

6nan is a 1 chain structure with sequence from Ixodes scapularis. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Solution NMR, 10 models
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

IXOSP_IXOSC Anticoagulant protein that modulates blood feeding of ticks on vertebrate species (PubMed:16807644, PubMed:32394234). Inhibits activation of host blood coagulation factor X (F10) (PubMed:11986214, PubMed:18042685, PubMed:28734839). Inhibits activity of host coagulation factor VIIa-tissue factor (F7-F3) complex in a factor X/Xa-dependent manner (PubMed:11986214). Prevents interaction between host coagulation factor X and activated factor VIIIa (F8) (PubMed:18042685).^[1] ^[2] ^[3] ^[4] ^[5]

Publication Abstract from PubMed

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.

NMR structure determination of Ixolaris and Factor X interaction reveals a noncanonical mechanism of Kunitz inhibition.,De Paula VS, Sgourakis NG, Francischetti IMB, Almeida FCL, Monteiro RQ Prof, Valente AP Blood. 2019 May 27. pii: blood.2018889493. doi: 10.1182/blood.2018889493. PMID:31133602^[6]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Francischetti IM, Valenzuela JG, Andersen JF, Mather TN, Ribeiro JM. Ixolaris, a novel recombinant tissue factor pathway inhibitor (TFPI) from the salivary gland of the tick, Ixodes scapularis: identification of factor X and factor Xa as scaffolds for the inhibition of factor VIIa/tissue factor complex. Blood. 2002 May 15;99(10):3602-12. PMID:11986214 doi:10.1182/blood-2001-12-0237
↑ Nazareth RA, Tomaz LS, Ortiz-Costa S, Atella GC, Ribeiro JM, Francischetti IM, Monteiro RQ. Antithrombotic properties of Ixolaris, a potent inhibitor of the extrinsic pathway of the coagulation cascade. Thromb Haemost. 2006 Jul;96(1):7-13. PMID:16807644 doi:10.1160/TH06-02-0105
↑ Monteiro RQ, Rezaie AR, Bae JS, Calvo E, Andersen JF, Francischetti IM. Ixolaris binding to factor X reveals a precursor state of factor Xa heparin-binding exosite. Protein Sci. 2008 Jan;17(1):146-53. PMID:18042685 doi:10.1110/ps.073016308
↑ De Paula VS, Silva FHS, Francischetti IMB, Monteiro RQ, Valente AP. Recombinant expression of Ixolaris, a Kunitz-type inhibitor from the tick salivary gland, for NMR studies. Protein Expr Purif. 2017 Nov;139:49-56. PMID:28734839 doi:10.1016/j.pep.2017.07.012
↑ Barboza T, Gomes T, da Costa Medeiros P, Ramos IP, Francischetti I, Monteiro RQ, Gutfilen B, de Souza SAL. Development of (131)I-ixolaris as a theranostic agent: metastatic melanoma preclinical studies. Clin Exp Metastasis. 2020 Aug;37(4):489-497. PMID:32394234 doi:10.1007/s10585-020-10036-0
↑ De Paula VS, Sgourakis NG, Francischetti IMB, Almeida FCL, Monteiro RQ Prof, Valente AP. NMR structure determination of Ixolaris and Factor X interaction reveals a noncanonical mechanism of Kunitz inhibition. Blood. 2019 May 27. pii: blood.2018889493. doi: 10.1182/blood.2018889493. PMID:31133602 doi:https://dx.doi.org/10.1182/blood.2018889493

Proteopedia Page Contributors and Editors (what is this?)

OCA

[1] Francischetti IM, Valenzuela JG, Andersen JF, Mather TN, Ribeiro JM. Ixolaris, a novel recombinant tissue factor pathway inhibitor (TFPI) from the salivary gland of the tick, Ixodes scapularis: identification of factor X and factor Xa as scaffolds for the inhibition of factor VIIa/tissue factor complex. Blood. 2002 May 15;99(10):3602-12. PMID:11986214 doi:10.1182/blood-2001-12-0237

[2] Nazareth RA, Tomaz LS, Ortiz-Costa S, Atella GC, Ribeiro JM, Francischetti IM, Monteiro RQ. Antithrombotic properties of Ixolaris, a potent inhibitor of the extrinsic pathway of the coagulation cascade. Thromb Haemost. 2006 Jul;96(1):7-13. PMID:16807644 doi:10.1160/TH06-02-0105

[3] Monteiro RQ, Rezaie AR, Bae JS, Calvo E, Andersen JF, Francischetti IM. Ixolaris binding to factor X reveals a precursor state of factor Xa heparin-binding exosite. Protein Sci. 2008 Jan;17(1):146-53. PMID:18042685 doi:10.1110/ps.073016308

[4] De Paula VS, Silva FHS, Francischetti IMB, Monteiro RQ, Valente AP. Recombinant expression of Ixolaris, a Kunitz-type inhibitor from the tick salivary gland, for NMR studies. Protein Expr Purif. 2017 Nov;139:49-56. PMID:28734839 doi:10.1016/j.pep.2017.07.012

[5] Barboza T, Gomes T, da Costa Medeiros P, Ramos IP, Francischetti I, Monteiro RQ, Gutfilen B, de Souza SAL. Development of (131)I-ixolaris as a theranostic agent: metastatic melanoma preclinical studies. Clin Exp Metastasis. 2020 Aug;37(4):489-497. PMID:32394234 doi:10.1007/s10585-020-10036-0

[6] De Paula VS, Sgourakis NG, Francischetti IMB, Almeida FCL, Monteiro RQ Prof, Valente AP. NMR structure determination of Ixolaris and Factor X interaction reveals a noncanonical mechanism of Kunitz inhibition. Blood. 2019 May 27. pii: blood.2018889493. doi: 10.1182/blood.2018889493. PMID:31133602 doi:https://dx.doi.org/10.1182/blood.2018889493

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6nan

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

Structural highlights

Function

Publication Abstract from PubMed

References

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