FIG. 2.
Results of gel shift experiment showing MarA and RNAP binding to wild-type robWT (A) and mutant rob10 (B) promoters at 4°C and 37°C. 4°C, incubation was all at 4°C. 37°C, MarA and RNAP were preincubated together at 4°C with DNA followed by the formation of stable RNAP-DNA initiation complexes in the presence of three nucleotides at 37°C. All samples are from the same gel and experiment. For details, see Materials and Methods. The rob DNA concentration was 10 nM. For panel A at 4°C, the lanes indicated by an asterisk received salmon sperm DNA at 5 μg/ml at the end of the reaction. The fluorescent band in the top of the wells was seen even in the absence of sample. DNA was detected by fluorescence; MarA was detected by anti-MarA. D, free DNA; RD, RNAP-DNA; RDM, RNAP-DNA-MarA; DM, DNA-MarA.