2IMK

Structures of an Insect Epsilon-class Glutathione S-transferase from the Malaria Vector Anopheles Gambiae: Evidence for High DDT-detoxifying Activity


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.196 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure of an insect epsilon class glutathione S-transferase from the malaria vector Anopheles gambiae provides an explanation for the high DDT-detoxifying activity

Wang, Y.Qiu, L.Ranson, H.Lumjuan, N.Hemingway, J.Setzer, W.N.Meehan, E.J.Chen, L.

(2008) J.Struct.Biol. 164: 228-235

  • DOI: 10.1016/j.jsb.2008.08.003
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Glutathione S-transferases (GSTs), a major family of detoxifying enzymes, play a pivotal role in insecticide resistance in insects. In the malaria vector Anopheles gambiae, insect-specific epsilon class GSTs are associated with resistance to the orga ...

    Glutathione S-transferases (GSTs), a major family of detoxifying enzymes, play a pivotal role in insecticide resistance in insects. In the malaria vector Anopheles gambiae, insect-specific epsilon class GSTs are associated with resistance to the organochlorine insecticide DDT [1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane]. Five of the eight class members have elevated expression levels in a DDT resistant strain. agGSTe2 is considered the most important GST in conferring DDT resistance in A. gambiae, and is the only member of the epsilon class with confirmed DDT-metabolizing activity. A delta class GST from the same species shows marginal DDT-metabolizing activity but the activity of agGSTe2 is approximately 350x higher than the delta class agGST1-6. To investigate its catalytic mechanism and the molecular basis of its unusually high DDT-metabolizing ability, three agGSTe2 crystal structures including one apo form and two binary complex forms with the co-factor glutathione (GSH) or the inhibitor S-hexylglutathione (GTX) have been solved with a resolution up to 1.4A. The structure of agGSTe2 shows the canonical GST fold with a highly conserved N-domain and a less conserved C-domain. The binding of GSH or GTX does not induce significant conformational changes in the protein. The modeling of DDT into the putative DDT-binding pocket suggests that DDT is likely to be converted to DDE [1,1-dichloro-2,2-bis-(p-chlorophenyl)ethylene] through an elimination reaction triggered by the nucleophilic attack of the thiolate group of GS(-) on the beta-hydrogen of DDT. The comparison with the less active agGST1-6 provides the structural evidence for its high DDT-detoxifying activity. In short, this is achieved through the inclination of the upper part of H4 helix (H4'' helix), which brings residues Arg112, Glu116, and Phe120 closer to the GSH-binding site resulting in a more efficient GS(-)-stabilizing hydrogen-bond-network and higher DDT-binding affinity.


    Organizational Affiliation

    Laboratory for Structural Biology, Department of Chemistry, Graduate Program of Biotechnology, University of Alabama in Huntsville, Huntsville, AL 35899, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Epsilon-class Glutathione S-transferase
A, B
221Anopheles gambiaeMutation(s): 0 
Gene Names: GSTE2 (1280155)
Find proteins for Q7PVS6 (Anopheles gambiae)
Go to UniProtKB:  Q7PVS6
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GTX
Query on GTX

Download SDF File 
Download CCD File 
A, B
S-HEXYLGLUTATHIONE
C16 H30 N3 O6 S
HXJDWCWJDCOHDG-RYUDHWBXSA-O
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.196 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 49.512α = 90.00
b = 85.481β = 90.00
c = 93.265γ = 90.00
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction
REFMACrefinement
SCALEPACKdata scaling
DENZOdata reduction
MOLREPphasing
HKL-2000data reduction
HKL-2000data collection
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-10-09
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2017-10-18
    Type: Refinement description