Crystal structure of the I219A mutant of human glutathione transferase A1-1 with S-hexylglutathione

Experimental Data Snapshot

  • Resolution: 1.95 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.218 

Starting Model: experimental
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Tertiary Interactions Stabilise the C-terminal Region of Human Glutathione Transferase A1-1: a Crystallographic and Calorimetric Study.

Kuhnert, D.C.Sayed, Y.Mosebi, S.Sayed, M.Sewell, T.Dirr, H.W.

(2005) J Mol Biol 349: 825-838

  • DOI: https://doi.org/10.1016/j.jmb.2005.04.025
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The C-terminal region in class Alpha glutathione transferase A1-1 (GSTA1-1), which forms an amphipathic alpha-helix (helix 9), is known to contribute to the catalytic and non-substrate ligand-binding functions of the enzyme. The region in the apo protein is proposed to be disordered which, upon ligand binding at the active-site, becomes structured and localised. Because Ile219 plays a pivotal role in the stability and localisation of the region, the role of tertiary interactions mediated by Ile219 in determining the conformation and dynamics of the C-terminal region were studied. Ligand-binding microcalorimetric and X-ray structural data were obtained to characterise ligand binding at the active-site and the associated localisation of the C-terminal region. In the crystal structure of the I219A hGSTA1-1.S-hexylglutathione complex, the C-terminal region of one chain is mobile and not observed (unresolved electron density), whereas the corresponding region of the other chain is localised and structured as a result of crystal packing interactions. In solution, the mutant C-terminal region of both chains in the complex is mobile and delocalised resulting in a hydrated, less hydrophobic active-site and a reduction in the affinity of the protein for S-hexylglutathione. Complete dehydration of the active-site, important for maintaining the highly reactive thiolate form of glutathione, requires the binding of ligands and the subsequent localisation of the C-terminal region. Thermodynamic data demonstrate that the mobile C-terminal region in apo hGSTA1-1 is structured and does not undergo ligand-induced folding. Its close proximity to the surface of the wild-type protein is indicated by the concurrence between the observed heat capacity change of complex formation and the type and amount of surface area that becomes buried at the ligand-protein interface when the C-terminal region in the apo protein assumes the same localised structure as that observed in the wild-type complex.

  • Organizational Affiliation

    Protein Structure-Function Research Programme, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, 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
Binding Affinity Annotations 
IDSourceBinding Affinity
GTX PDBBind:  1YDK Kd: 1300 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 1.95 Å
  • R-Value Free: 0.253 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.218 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 99.53α = 90
b = 91.472β = 92.4
c = 51.482γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data reduction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-06-07
    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: 2017-10-11
    Changes: Refinement description
  • Version 1.4: 2021-10-20
    Changes: Database references, Derived calculations
  • Version 1.5: 2023-08-23
    Changes: Data collection, Refinement description