1YDK

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

Summary for 1YDK

• Entry DOI: 10.2210/pdb1ydk/pdb
• Descriptor: Glutathione S-transferase A1, S-HEXYLGLUTATHIONE (3 entities in total)
• Functional Keywords: glutathione transferase, s-hexylglutathione, transferase
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: P08263
• Total number of polymer chains: 2
• Total formula weight: 52041.06

Authors

Kuhnert, D.C.,Sayed, Y.,Mosebi, S.,Sayed, M.,Sewell, T.,Dirr, H.W. (deposition date: 2004-12-24, release date: 2005-06-07, Last modification date: 2023-08-23)

Primary citation

Kuhnert, D.C.,Sayed, Y.,Mosebi, S.,Sayed, M.,Sewell, T.,Dirr, H.W.
Tertiary Interactions Stabilise the C-terminal Region of Human Glutathione Transferase A1-1: a Crystallographic and Calorimetric Study.
J.Mol.Biol., 349:825-838, 2005

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.

PubMed: 15893769
DOI: 10.1016/j.jmb.2005.04.025

Experimental method

X-RAY DIFFRACTION (1.95 Å)