Fig. 6

Reversible inhibition of the DNA binding activity of AtsR by H₂O₂ and role of cysteine residue. A Inhibition of the DNA binding activity of AtsR by H₂O₂ and reversal of the inhibition by DTT. AtsR was prepared in three different concentrations, and aliquots were taken for EMSAs (Control). Then H₂O₂ was added to the binding reaction mixture to a final concentration of 0.5 mM, and aliquots were taken for EMSA. In the next step DTT (a final concentration of 50 mM) was added to 0.5 mM H₂O₂-containing binding reaction mixture, and aliquots were taken for EMSAs. All aliquots were incubated in binding buffer, pH 8.0, with 40 ng P_ncgl0887 and then separated on an 8% native polyacrylamide gel. B STR was added to the binding reaction mixture to a final concentration of 2 µg/ml, and the interaction between AtsR and P_ncgl0887 was performed. C The interaction between the mutated derivatives AtsR:C123SC187S and P_ncgl0887 in the absence (left panel) or presence (right left) of 5 mM H₂O₂. Results were obtained in three independent experiments, and data show one representative experiment done in triplicate