4GTU

LIGAND-FREE HOMODIMERIC HUMAN GLUTATHIONE S-TRANSFERASE M4-4

Summary for 4GTU

• Entry DOI: 10.2210/pdb4gtu/pdb
• Related: 1GTU 2GTU 3GTU
• Descriptor: GLUTATHIONE S-TRANSFERASE (1 entity in total)
• Functional Keywords: transferase, glutathione, conjugation, detoxification, cytosolic, homodimer
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: Q03013
• Total number of polymer chains: 8
• Total formula weight: 203697.31

Authors

Patskovsky, Y.V.,Patskovska, L.N.,Listowsky, I. (deposition date: 1999-05-12, release date: 2000-01-14, Last modification date: 2023-09-13)

Primary citation

Patskovsky, Y.V.,Patskovska, L.N.,Listowsky, I.
An asparagine-phenylalanine substitution accounts for catalytic differences between hGSTM3-3 and other human class mu glutathione S-transferases.
Biochemistry, 38:16187-16194, 1999

PubMed Abstract: The hGSTM3 subunit, which is preferentially expressed in germ-line cells, has the greatest sequence divergence among the human mu class glutathione S-transferases. To determine a structural basis for the catalytic differences between hGSTM3-3 and other mu class enzymes, chimeric proteins were designed by modular interchange of the divergent C-terminal domains of hGSTM3 and hGSTM5 subunits. Replacement of 24 residues of the C-terminal segment of either subunit produced chimeric enzymes with catalytic properties that reflected those of the wild-type enzyme from which the C-terminus had been derived. Deletion of the tripeptide C-terminal extension found only in the hGSTM3 subunit had no effect on catalysis. The crystal structure determined for a ligand-free hGSTM3 subunit indicates that an Asn212 residue of the C-terminal domain is near a hydrophobic cluster of side chains formed in part by Ile13, Leu16, Leu114, Ile115, Tyr119, Ile211, and Trp218. Accordingly, a series of point mutations were introduced into the hGSTM3 subunit, and it was indeed determined that a Y119F mutation considerably enhanced the turnover rate of the enzyme for nucleophilic aromatic substitution reactions. A more striking effect was observed for a double mutant (Y119F/N212F) which had a k(cat)/K(m)(CDNB) value of 7.6 x 10(5) s(-)(1) M(-)(1) as compared to 4.9 x 10(3) s(-)(1) M(-)(1) for the wild-type hGSTM3-3 enzyme. The presence of a polar Asn212 in place of a Phe residue found in the cognate position of other mu class glutathione S-transferases, therefore, has a marked influence on catalysis by hGSTM3-3.

PubMed: 10587441
DOI: 10.1021/bi991714t

Experimental method

X-RAY DIFFRACTION (3.3 Å)