Fig. 3

EMSA for OxyR’s binding to catB promoter region. Purified OxyR at 5 nM was incubated with 2 nM probe (FAM-labeled catB promoter DNA region (length-312/+78)) at 25 °C for 30 min, and the products were run a native 4 % (W/V) polyacrylamide gel in 0.5 × TBE buffer for about 1.5 h at 100 V. Cold probe (unlabeled catB promoter DNA region) at 20 nM was used as specific DNA competitor and negative probe (unlabeled coding region of 16S rRNA gene) at 20 nM is used as nonspecific DNA competitor. Bovine Serum Albumin (BSA) at 5 nM was used as the non-specific protein competitor. The addition of OxyR, probes and BSA was indicated by the ‘+’ sign and the omission was indicated by the ‘-’ sign. B: binding probe, F: free probe