1GXF

CRYSTAL STRUCTURE OF TRYPANOSOMA CRUZI TRYPANOTHIONE REDUCTASE IN COMPLEX WITH THE INHIBITOR QUINACRINE MUSTARD


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.190 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Two Interacting Binding Sites for Quinacrine Derivatives in the Active Site of Trypanothione Reductase: A Template for Drug Design

Saravanamuthu, A.Vickers, T.J.Bond, C.S.Peterson, M.R.Hunter, W.N.Fairlamb, A.H.

(2004) J Biol Chem 279: 29493

  • DOI: 10.1074/jbc.M403187200
  • Primary Citation of Related Structures:  
    1GXF

  • PubMed Abstract: 
  • Trypanothione reductase is a key enzyme in the trypanothione-based redox metabolism of pathogenic trypanosomes. Because this system is absent in humans, being replaced with glutathione and glutathione reductase, it offers a target for selective inhib ...

    Trypanothione reductase is a key enzyme in the trypanothione-based redox metabolism of pathogenic trypanosomes. Because this system is absent in humans, being replaced with glutathione and glutathione reductase, it offers a target for selective inhibition. The rational design of potent inhibitors requires accurate structures of enzyme-inhibitor complexes, but this is lacking for trypanothione reductase. We therefore used quinacrine mustard, an alkylating derivative of the competitive inhibitor quinacrine, to probe the active site of this dimeric flavoprotein. Quinacrine mustard irreversibly inactivates Trypanosoma cruzi trypanothione reductase, but not human glutathione reductase, in a time-dependent manner with a stoichiometry of two inhibitors bound per monomer. The rate of inactivation is dependent upon the oxidation state of trypanothione reductase, with the NADPH-reduced form being inactivated significantly faster than the oxidized form. Inactivation is slowed by clomipramine and a melarsen oxide-trypanothione adduct (both are competitive inhibitors) but accelerated by quinacrine. The structure of the trypanothione reductase-quinacrine mustard adduct was determined to 2.7 A, revealing two molecules of inhibitor bound in the trypanothione-binding site. The acridine moieties interact with each other through pi-stacking effects, and one acridine interacts in a similar fashion with a tryptophan residue. These interactions provide a molecular explanation for the differing effects of clomipramine and quinacrine on inactivation by quinacrine mustard. Synergism with quinacrine occurs as a result of these planar acridines being able to stack together in the active site cleft, thereby gaining an increased number of binding interactions, whereas antagonism occurs with nonplanar molecules, such as clomipramine, where stacking is not possible.


    Organizational Affiliation

    Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
TRYPANOTHIONE REDUCTASE (OXIDIZED FORM)AB492Trypanosoma cruziMutation(s): 7 
Gene Names: TPR
EC: 1.6.4.8 (PDB Primary Data), 1.8.1.12 (UniProt)
Find proteins for P28593 (Trypanosoma cruzi)
Explore P28593 
Go to UniProtKB:  P28593
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
FAD
Query on FAD

Download CCD File 
A, B
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
 Ligand Interaction
QUM
Query on QUM

Download CCD File 
A, B
QUINACRINE MUSTARD
C23 H28 Cl3 N3 O
UKOBAUFLOGFCMV-INIZCTEOSA-N
 Ligand Interaction
MAE
Query on MAE

Download CCD File 
A
MALEIC ACID
C4 H4 O4
VZCYOOQTPOCHFL-UPHRSURJSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.250 
  • R-Value Work: 0.190 
  • Space Group: P 43
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 93.1α = 90
b = 93.1β = 90
c = 156.6γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-05-06
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance