Crystal Structure of hGSTA3-3 in Complex with Glutathione

Experimental Data Snapshot

  • Resolution: 2.40 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.228 
  • R-Value Observed: 0.228 

Starting Model: experimental
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Crystal structure of human glutathione S-transferase A3-3 and mechanistic implications for its high steroid isomerase activity.

Gu, Y.Guo, J.Pal, A.Pan, S.S.Zimniak, P.Singh, S.V.Ji, X.

(2004) Biochemistry 43: 15673-15679

  • DOI: https://doi.org/10.1021/bi048757g
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The crystal structure of human class alpha glutathione (GSH) S-transferase A3-3 (hGSTA3-3) in complex with GSH was determined at 2.4 A. Despite considerable amino acid sequence identity with other human class alpha GSTs (e.g., hGSTA1-1), hGSTA3-3 is unique due to its exceptionally high steroid double bond isomerase activity for the transformation of Delta(5)-androstene-3,17-dione (Delta(5)-AD) to Delta(4)-androstene-3,17-dione. A comparative analysis of the active centers of hGSTA1-1 and hGSTA3-3 reveals that residues in positions 12 and 208 may contribute to their disparate isomerase activity toward Delta(5)-AD. Substitution of these two residues of hGSTA3-3 with the corresponding residues in hGSTA1-1 followed by kinetic characterization of the wild-type and the mutant enzymes supported this prediction. On the basis of our model of the hGSTA3-3.GSH.Delta(5)-AD ternary complex and available biochemical data, we propose that the thiolate group of deprotonated GSH (GS(-)) serves as a base to initiate the reaction by accepting a proton from the steroid and the nonionized hydroxyl group of catalytic residue Y9 (HO-Y9) functions as part of a proton-conducting wire to transfer a proton back to the steroid. Residue R15 may function to stabilize the deprotonated thiolate group of GSH (GS(-)), and a GSH-bound water molecule may donate a hydrogen bond to the 3-keto group of Delta(5)-AD and thus help the thiolate of GS(-) to initiate the proton transfer and the subsequent stabilization of the reaction intermediate.

  • Organizational Affiliation

    Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland 21702, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glutathione S-transferase A3-3
A, B
222Homo sapiensMutation(s): 0 
Gene Names: GSTA3
UniProt & NIH Common Fund Data Resources
Find proteins for Q16772 (Homo sapiens)
Explore Q16772 
Go to UniProtKB:  Q16772
PHAROS:  Q16772
GTEx:  ENSG00000174156 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ16772
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.40 Å
  • R-Value Free: 0.252 
  • R-Value Work: 0.228 
  • R-Value Observed: 0.228 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 92.985α = 90
b = 95.588β = 90.14
c = 114.039γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-01-18
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2014-09-17
    Changes: Other
  • Version 1.4: 2023-08-23
    Changes: Data collection, Database references, Derived calculations, Refinement description
  • Version 1.5: 2023-08-30
    Changes: Database references, Structure summary