4GSS

HUMAN GLUTATHIONE S-TRANSFERASE P1-1 Y108F MUTANT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.198 

Starting Model: experimental
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This is version 1.5 of the entry. See complete history


Literature

Multifunctional role of Tyr 108 in the catalytic mechanism of human glutathione transferase P1-1. Crystallographic and kinetic studies on the Y108F mutant enzyme.

Lo Bello, M.Oakley, A.J.Battistoni, A.Mazzetti, A.P.Nuccetelli, M.Mazzarese, G.Rossjohn, J.Parker, M.W.Ricci, G.

(1997) Biochemistry 36: 6207-6217

  • DOI: https://doi.org/10.1021/bi962813z
  • Primary Citation of Related Structures:  
    4GSS

  • PubMed Abstract: 

    The possible role of the hydroxyl group of Tyr 108 in the catalytic mechanism of human glutathione transferase P1-1 has been investigated by means of site-directed mutagenesis, steady-state kinetic analysis, and crystallographic studies. Three representative cosubstrates have been used, i.e. ethacrynic acid, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, and 1-chloro-2,4-dinitrobenzene. In the presence of ethacrynic acid, the enzyme follows a rapid equilibrium random bi-bi mechanism with a rate-limiting step which occurs after the addition of the substrates and before the release of products. The replacement of Tyr 108 with Phe yields a 14-fold decrease of k(cat), while it does not change appreciably the affinity of the H site for the substrate. In this case, it would appear that the role of the hydroxyl function is to stabilize the transition state for the chemical step, i.e. the Michael addition of GSH to the electrophilic substrate. Crystallographic data are compatible with this conclusion showing the hydroxyl group of Y108 in hydrogen bonding distance of the ketone moiety of ethacrynic acid [Oakley, A. J., Rossjohn, J., Lo Bello, M., Caccuri, A. M., Federici, G., & Parker, M. W. (1997) Biochemistry 36, 576-585]. Moreover, no structural differences are observed between the Y108F mutant and the wild type, suggesting that the removal of the hydroxyl group is solely responsible for the loss of activity. A different involvement of Tyr 108 appears in the catalyzed conjugation of 7-chloro-4-nitrobenz-2-oxa-1,3-diazole with GSH in which the rate-limiting step is of a physical nature, probably a structural transition of the ternary complex. The substitution of Tyr 108 yields an approximately 7-fold increase of k(cat) and a constant k(cat)/Km(NBD-Cl) value. Lack of a critical hydrogen bond between 7-chloro-4-nitrobenz-2-oxa-1,3-diazole and Tyr 108 appears to be the basis of the increased k(cat). In the 1-chloro-2,4-dinitrobenzene/GSH system, no appreciable changes of kinetics parameters are found in the Y108F mutant. We conclude that Y108 has a multifunctional role in glutathione transferase P1-1 catalysis, depending on the nature of the electrophilic cosubstrate.


  • Organizational Affiliation

    Department of Biology, University of Rome Tor Vergata, Italy.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
GLUTATHIONE S-TRANSFERASE
A, B
209Homo sapiensMutation(s): 1 
Gene Names: GTP_HUMAN
EC: 2.5.1.18
UniProt & NIH Common Fund Data Resources
Find proteins for P09211 (Homo sapiens)
Explore P09211 
Go to UniProtKB:  P09211
PHAROS:  P09211
GTEx:  ENSG00000084207 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP09211
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.50 Å
  • R-Value Free: 0.262 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.198 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 78.486α = 90
b = 90.339β = 97.47
c = 68.97γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
DENZOdata reduction
SCALEPACKdata scaling
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1998-01-28
    Type: Initial release
  • Version 1.1: 2008-03-03
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-11-03
    Changes: Database references, Derived calculations, Other
  • Version 1.4: 2023-08-09
    Changes: Refinement description
  • Version 1.5: 2024-05-22
    Changes: Data collection