Crystal structure of an R15L hGSTA1-1 mutant complexed with S-hexyl-glutathione

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.192 
  • R-Value Observed: 0.195 

Starting Model: experimental
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Arginine 15 stabilizes an S(N)Ar reaction transition state and the binding of anionic ligands at the active site of human glutathione transferase A1-1.

Gildenhuys, S.Dobreva, M.Kinsley, N.Sayed, Y.Burke, J.Pelly, S.Gordon, G.P.Sayed, M.Sewell, T.Dirr, H.W.

(2010) Biophys Chem 146: 118-125

  • DOI: https://doi.org/10.1016/j.bpc.2009.11.003
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Arg15, conserved in class Alpha GSTs (glutathione transferases), is located at the interface between the G- and H-sites of the active site where its cationic guanidinium group might play a role in catalysis and ligand binding. Arg15 in human GSTA1-1 was replaced with a leucine and crystallographic, spectroscopic, thermodynamic and molecular docking methods were used to investigate the contribution made by Arg15 towards (i) the binding of glutathione (GSH) to the G-site, (ii) the pK(a) of the thiol group of GSH, (iii) the stabilization of an analog of the anionic transition state of the S(N)Ar reaction between 1-chloro-2,4-dinitrobenzene (CDNB) and GSH, and, (iv) the binding of the anionic non-substrate ligand 8-anilino-1-naphthalene sulphonate (ANS) to the H-site. While the R15L mutation substantially diminishes the CDNB-GSH conjugating activity of the enzyme, it has little effect on protein structure and stability. Arg15 does not contribute significantly towards the enzyme's affinity for GSH but does determine the reactivity of GSH by reducing the thiol's pK(a) from 7.6 to 6.6. The anionic sigma-complex formed between GSH and 1,3,5-trinitrobenzene is stabilized by Arg15, suggesting that it also stabilizes the transition state formed in the S(N)Ar reaction between GSH and CDNB. The trinitrocyclohexadienate moiety of the sigma-complex binds the H-site where the catalytic residue, Tyr9, was identified to hydrogen bond to an o-nitro group of the sigma-complex. The affinity for ANS at the H-site is decreased about 3-fold by the R15L mutation implicating the positive electrostatic potential of Arg15 in securing the organic anion at this site.

  • Organizational Affiliation

    University of the Witwatersrand, Johannesburg, South Africa.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glutathione S-transferase A1
A, B
222Homo sapiensMutation(s): 1 
Gene Names: GSTA1
UniProt & NIH Common Fund Data Resources
Find proteins for P08263 (Homo sapiens)
Explore P08263 
Go to UniProtKB:  P08263
GTEx:  ENSG00000243955 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP08263
Sequence Annotations
  • Reference Sequence
Small Molecules
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.192 
  • R-Value Observed: 0.195 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 99.103α = 90
b = 93.858β = 93.9
c = 51.566γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data collection

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-12-18
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-10-25
    Changes: Refinement description
  • Version 1.3: 2021-10-20
    Changes: Database references, Derived calculations
  • Version 1.4: 2023-08-30
    Changes: Data collection, Refinement description