2ESU

Crystal structure of Asn to Gln mutant of Winged Bean Chymotrypsin Inhibitor protein


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.94 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.219 
  • R-Value Observed: 0.219 

wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

Spacer Asn Determines the Fate of Kunitz (STI) Inhibitors, as Revealed by Structural and Biochemical Studies on WCI Mutants.

Dasgupta, J.Khamrui, S.Dattagupta, J.K.Sen, U.

(2006) Biochemistry 45: 6783-6792

  • DOI: https://doi.org/10.1021/bi060374q
  • Primary Citation of Related Structures:  
    2BEA, 2BEB, 2ESU, 2ET2

  • PubMed Abstract: 

    The scaffold of serine protease inhibitors plays a significant role in the process of religation which resists proteolysis of the inhibitor in comparison to a substrate. Although the role of the conserved scaffolding Asn residue was previously implicated in the maintenance of the binding loop conformation of Kunitz (STI) inhibitors, its possible involvement in the prevention of proteolysis is still unexplored. In this paper, we have investigated the specific role of the spacer Asn in the prevention of proteolysis through structural and biochemical studies on the mutants where Asn14 of winged bean chymotrypsin inhibitor (WCI) has been replaced by Gly, Ala, Thr, Leu, and Gln. A residue having no side chain or beta-branching at the 14th position creates deformation and insufficient protrusion of the binding loop, and as a result N14G and N14T lose the ability to recognize proteases. Although the reactive site loop conformation of N14A and N14Q are almost identical to WCI, biochemical results present N14A as a substrate indicating that the methyl group of Ala14 is not suitable to capture the cleaved parts together for religation. The poor inhibitory power of N14L points toward the chemical incompatibility of Leu at the 14th position, although its size is the same as Asn; on the other hand, slight loss of inhibitory potency of N14Q is attributed to the inappropriate placement of the Gln14 polar head, caused by the strained accommodation of its bigger side chain. These observations collectively allow us to conclude that the side chain of spacer Asn fits snugly into the concave space of the reactive site loop cavity and its ND2 atom forms hydrogen bonds with the P2 and P1' carbonyl O at either side of the scissile bond holding the cleaved products together for religation. Through database analysis, we have identified such spacer asparagines in five other families of serine protease inhibitors with a similar disposition of their ND2 atoms, which supports our proposition.


  • Organizational Affiliation

    Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064, India.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Chymotrypsin inhibitor 3186Psophocarpus tetragonolobusMutation(s): 1 
UniProt
Find proteins for P10822 (Psophocarpus tetragonolobus)
Explore P10822 
Go to UniProtKB:  P10822
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP10822
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download Ideal Coordinates CCD File 
C [auth A]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
NI
Query on NI

Download Ideal Coordinates CCD File 
B [auth A]NICKEL (II) ION
Ni
VEQPNABPJHWNSG-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.94 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.219 
  • R-Value Observed: 0.219 
  • Space Group: P 61 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 60.9α = 90
b = 60.9β = 90
c = 213.21γ = 120
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
SCALEPACKdata scaling
CNSphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-06-13
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2018-04-04
    Changes: Data collection
  • Version 1.4: 2021-10-20
    Changes: Database references, Derived calculations