Site‐directed mutagenesis of the Proteus mirabilis glutathione transferase B1‐1 G‐site

Abstract

In order to investigate the roles of near N-terminus Tyr, Cys, and Ser residues in the activity of bacterial glutathione transferase (GSTB1-1) site-directed mutagenesis was used to replace the following residues: Tyr-4, Tyr-5, Ser-9, Cys-10, Ser-11, and Ser-13. The results presented here show that, unlike all other alpha, mu, pi, theta and sigma classes of glutathione transferases so far investigated, GSTB1-1 does not utilise any Tyr, Ser or Cys residue to activate glutathione. These results also suggest that the bacterial glutathione transferases may require classification into their own class.z 1998 Federation of European Biochemical Societies.

Structures of Ternary Complexes of BphK, a Bacterial Glutathione S-Transferase That Reductively Dechlorinates Polychlorinated Biphenyl Metabolites

“…Mutation of Cys-10 to Ser or Ala of PmGST B1-1 did not significantly reduce activity toward CDNB, a synthetic reporter substrate (19). Furthermore, the conservative mutation of His-106 to Asn had a greater impact on substrate binding than on catalysis using the same reporter substrate (20).…”

“…Furthermore, the conservative mutation of His-106 to Asn had a greater impact on substrate binding than on catalysis using the same reporter substrate (20). Finally, mutational analysis of Ser, Tyr, and Thr residues in the active site failed to identify catalytically essential groups for GSH activation toward CDNB (19).…”

“…Instead, two conserved residues, Cys-10 and His-106, interact directly with the GSH substrate and are ascribed catalytic roles (8). Sitedirected mutagenesis studies using 1-chloro-2,4-dinitrobenzene (CDNB) as a reporter substrate failed to identify active site residues that activate the glutathione (19,20).…”

The Specific Interaction of Dinitrosyl-Diglutathionyl-Iron Complex, a Natural NO Carrier, with the Glutathione Transferase Superfamily

“…This enzyme shows a Cys residue (Cys-10) instead of Tyr or Ser residues in a proper distance from the sulfur atom of GSH (16,51). In addition, the native enzyme displays an unusual mixed disulfide involving Cys-10 and the bound GSH which rapidly exchange with a second GSH molecule transiently present in the G-site (52,53).…”

A glutathione S-transferase from Proteus mirabilis involved in heavy metal resistance and its potential application in removal of Hg2+

“…In Proteus mirabilis, three forms of GSTs had been explored [13]. P. mirabilis GST B1-1, the first cGST of beta class, was extensively studied relating to its structure and function [6,[14][15][16][17][18][19][20][21][22]. But little information about the character and function of other forms of GSTs from P. mirabilis was reported.…”