Catalyzes the conjugation of reduced glutathione (GSH) to a wide number of exogenous and endogenous hydrophobic electrophiles. Shows activity toward 1-chloro-2,4-dinitrobenzene (CDNB) and ethacrynic acid. Also possesses thiol:disulfide oxidoreductase activity, using GSH to reduce bis-(2-hydroxyethyl) disulfide (HEDS). Has a low level of glutathione-dependent peroxidase activity toward cumene hydroperoxide. Is important for defense against oxidative stress, probably via its peroxidase activity. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) kcat is 9 sec(-1) for the GSH transferase reaction with CDNB as substrate. Optimum pH is 7.5. Optimum temperature is 35 degrees Celsius. Homodimer. Deletion of the gstA gene decreases the resistance of the bacteria to hydrogen peroxide. Belongs to the GST superfamily. Beta family.