4U7H

Oxidized quinone reductase 2 in complex with CK2 inhibitor DMAT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.48 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.179 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Quinone Reductase 2 Is an Adventitious Target of Protein Kinase CK2 Inhibitors TBBz (TBI) and DMAT.

Leung, K.K.Shilton, B.H.

(2015) Biochemistry 54: 47-59

  • DOI: 10.1021/bi500959t
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Quinone reductase 2 (NQO2) exhibits off-target interactions with two protein kinase CK2 inhibitors, 4,5,6,7-1H-tetrabromobenzimidazole (TBBz) and 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT). TBBz and DMAT induce apoptosis in cells expr ...

    Quinone reductase 2 (NQO2) exhibits off-target interactions with two protein kinase CK2 inhibitors, 4,5,6,7-1H-tetrabromobenzimidazole (TBBz) and 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT). TBBz and DMAT induce apoptosis in cells expressing an inhibitor-resistant CK2, suggesting that the interaction with NQO2 may mediate some of their pharmacological effects. In this study, we have fully characterized the binding of TBBz and DMAT to NQO2. Fluorescence titrations showed that TBBz and DMAT bind oxidized NQO2 in the low nanomolar range; in the case of TBBz, the affinity for NQO2 was 40-fold greater than its affinity for CK2. A related CK2 inhibitor, 4,5,6,7-tetrabromobenzotriazole (TBB), which failed to cause apoptosis in cells expressing inhibitor-resistant CK2, binds NQO2 with an affinity 1000-fold lower than those of TBBz and DMAT. Kinetic analysis indicated that DMAT inhibits NQO2 by binding with similar affinities to the oxidized and reduced forms. Crystal structure analysis showed that DMAT binds reduced NQO2 in a manner different from that in the oxidized state. In oxidized NQO2, TBBz and DMAT are deeply buried in the active site and make direct hydrogen and halogen bonds to the enzyme. In reduced NQO2, DMAT occupies a more peripheral region and hydrogen and halogen bonds with the enzyme are mediated through three water molecules. Therefore, although TBB, TBBz, and DMAT are all potent inhibitors of CK2, they exhibit different activity profiles toward NQO2. We conclude that the active site of NQO2 is fundamentally different from the ATP binding site of CK2 and the inhibition of NQO2 by CK2 inhibitors is adventitious.


    Organizational Affiliation

    Department of Biochemistry, University of Western Ontario , London, Ontario, Canada N6A 5C1.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Ribosyldihydronicotinamide dehydrogenase [quinone]
A, B
230Homo sapiensMutation(s): 0 
Gene Names: NQO2 (NMOR2)
EC: 1.10.5.1
Find proteins for P16083 (Homo sapiens)
Go to Gene View: NQO2
Go to UniProtKB:  P16083
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download SDF File 
Download CCD File 
A, B
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
K25
Query on K25

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Download CCD File 
B
4,5,6,7-TETRABROMO-N,N-DIMETHYL-1H-BENZIMIDAZOL-2-AMINE
DIMETHYL-(4,5,6,7-TETRABROMO-1H-BENZOIMIDAZOL-2-YL)-AMINE
C9 H7 Br4 N3
SLPJGDQJLTYWCI-UHFFFAOYSA-N
 Ligand Interaction
FAD
Query on FAD

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Download CCD File 
A, B
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
K25Kd: 36.4 nM (99) BINDINGDB
K25IC50: 484 nM (99) BINDINGDB
K25Kd: 36.4 nM BINDINGMOAD
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.48 Å
  • R-Value Free: 0.207 
  • R-Value Work: 0.179 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 56.250α = 90.00
b = 83.010β = 90.00
c = 106.480γ = 90.00
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
SCALAdata scaling
MOSFLMdata reduction
PHENIXrefinement
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2015-02-11
    Type: Initial release
  • Version 1.1: 2017-11-22
    Type: Database references, Derived calculations, Refinement description, Source and taxonomy