Skip navigation
Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/1638
Title: Structural basis for dual inhibitory role of tamarind Kunitz inhibitor (TKI) against factor Xa and trypsin
Authors: Patil D.N.
Chaudhary A.
Sharma, Ashwani Kumar
Tomar, Shailly
Kumar, Pravindra R.Manish
Published in: FEBS Journal
Abstract: A Kunitz type dual inhibitor (TKI) of factor Xa (FXa) and trypsin was found in tamarind. It also shows prolongation of blood coagulation time. The deduced 185 amino acid sequence of TKI by cDNA cloning and sequence analysis revealed that it belongs to the Kunitz type soybean trypsin inhibitor (STI) family; however, it has a distorted Kunitz signature sequence due to insertion of Asn15 in the motif. TKI exhibited a competitive inhibitory activity against both FXa (Ki = 220 nm) and porcine pancreatic trypsin (Ki = 3.2 nm). The crystal structure of TKI shows a ?-trefoil fold similar to Kunitz STI inhibitors; however, a distinct mobile reactive site, an inserted residue and loop ?7?8 make it distinct from classical Kunitz inhibitors. The crystal structure of TKI-trypsin and a 3D model of TKI-FXa complex revealed that the distinct reactive site loop probably plays a role in dual inhibition. The reactive site of TKI interacts with an active site and two exosites (36 loop and autolysis loop) of FXa. Apart from Arg66 (P1), Arg64 (P3) is one of the most important residues responsible for the specificity of TKI towards FXa. Along with the reactive site loop (?4?5), loops ?1 and ?7?8 also interact with FXa and could further confer selectivity for FXa. We also present the role of inserted Asn15 in the stabilization of complexes. To the best of our knowledge, this is the first structure of FXa inhibitor belonging to the Kunitz type inhibitor family and its unique structural and sequence features make TKI a novel potent inhibitor. Database The complete nucleotide of TKI was deposited in the NCBI gene databank with accession no. HQ385502. The atomic coordinates and structure factor files for the structure of TKI and TKI:PPT complex have been deposited in the Protein Data Bank with accession numbers 4AN6 and 4AN7, respectively Structured digital abstract TKI and TKI bind by x-ray crystallography (View interaction) TKI and PPT bind by x-ray crystallography (View interaction) The dual inhibitory activity of Kunitz type dual inhibitor (TKI) of factor Xa (FXa) and trypsin has been investigated biochemically and structurally. The crystal structure of free TKI and its complex structure with trypsin were determined. Molecular docking was performed to examine the mode of interaction of TKI with FXa. Structural and modeling studies show that a versatile reactive site loop is responsible for dual inhibition © 2012 FEBS.
Citation: FEBS Journal(2012), 279(24): 4547-4564
URI: https://doi.org/10.1111/febs.12042
http://repository.iitr.ac.in/handle/123456789/1638
Issue Date: 2012
Keywords: factor Xa inhibitor
protein-protein interaction
tamarind Kunitz type inhibitor
versatile reactive site
X-ray structure
ISSN: 1742464X
Author Scopus IDs: 26431600400
26431275200
57214355701
57203506001
55064809000
Author Affiliations: Patil, D.N., Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
Chaudhary, A., Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
Sharma, A.K., Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
Tomar, S., Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
Kumar, P., Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
Corresponding Author: Tomar, S.; Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India; email: shaiprav@gmail.com
Appears in Collections:Journal Publications [BT]

Files in This Item:
There are no files associated with this item.
Show full item record


Items in Repository are protected by copyright, with all rights reserved, unless otherwise indicated.