PDBsum entry 6tkl

Blood clotting

PDB id: 6tkl

Contents

Protein chains

36 a.a.

251 a.a.

26 a.a.

Ligands

NAG

GOL

Metals

_NA

Waters ×256

PDB id:

6tkl

Name:

Blood clotting

Title:

Non-cleavable tsetse thrombin inhibitor in complex with human alpha- thrombin

Structure:

Prothrombin. Chain: l. Synonym: coagulation factor ii. Prothrombin. Chain: h. Synonym: coagulation factor ii. Tsetse thrombin inhibitor. Chain: i. Engineered: yes.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Synthetic: yes. Glossina morsitans morsitans. Organism_taxid: 37546

Resolution:

1.30Å R-factor: 0.147 R-free: 0.176

Authors:

B.M.Calisto,J.Ripoll-Rozada,D.De Sanctis,P.J.B.Pereira

Key ref:

B.M.Calisto et al. (2021). Sulfotyrosine-Mediated Recognition of Human Thrombin by a Tsetse Fly Anticoagulant Mimics Physiological Substrates. Cell Chem Biol, 28, 26. PubMed id: 33096052 DOI: 10.1016/j.chembiol.2020.10.002

Date:

28-Nov-19 Release date: 04-Nov-20

Protein chain

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 36 a.a.

Protein chain

P00734  (THRB_HUMAN) -  Prothrombin from Homo sapiens

Seq: 622 a.a.

Struc: 251 a.a.

Protein chain

O97373  (TTI_GLOMM) -  Tsetse thrombin inhibitor from Glossina morsitans morsitans

Seq: 53 a.a.

Struc: 26 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains L, H: E.C.3.4.21.5 - thrombin.
• Reaction: Preferential cleavage: Arg-|-Gly; activates fibrinogen to fibrin and releases fibrinopeptide A and B.

DOI no: 10.1016/j.chembiol.2020.10.002

Cell Chem Biol 28:26 (2021)

PubMed id: 33096052

Sulfotyrosine-Mediated Recognition of Human Thrombin by a Tsetse Fly Anticoagulant Mimics Physiological Substrates.

B.M.Calisto, J.Ripoll-Rozada, L.J.Dowman, C.Franck, S.M.Agten, B.L.Parker, R.C.Veloso, N.Vale, P.Gomes, D.de Sanctis, R.J.Payne, P.J.B.Pereira.

ABSTRACT

Despite possessing only 32 residues, the tsetse thrombin inhibitor (TTI) is among the most potent anticoagulants described, with sub-picomolar inhibitory activity against thrombin. Unexpectedly, TTI isolated from the fly is 2000-fold more active and 180 Da heavier than synthetic and recombinant variants. We predicted the presence of a tyrosine O-sulfate post-translational modification of TTI, prompting us to investigate the effect of the modification on anticoagulant activity. A combination of chemical synthesis and functional assays was used to reveal that sulfation significantly improved the inhibitory activity of TTI against thrombin. Using X-ray crystallography, we show that the N-terminal sulfated segment of TTI binds the basic exosite II of thrombin, establishing interactions similar to those of physiologic substrates, while the C-terminal segment abolishes the catalytic activity of thrombin. This non-canonical mode of inhibition, coupled with its potency and small size, makes TTI an attractive scaffold for the design of novel antithrombotics.