FIG. 6.
Gel mobility shift assay for chimeric protein and the LexA DNA-binding site upstream of psulA. A 64-bp double-stranded oligonucleotide was synthesized based on the nucleotide sequence of psulA. Whole-cell extracts were obtained by inducing a 100-ml culture, in mid-exponential phase, with 2 mM IPTG for 3 h. Culture (50 ml) was centrifuged, and bacteria were resuspended in 1 ml of TEN buffer and lysed in a French press (18,000 lb/in2). All lanes contained the labeled 64-bp dsDNA fragment. The lane containing no extract contained labeled DNA only. JL1436, LexA, and UreR1–182-LexA1–87 whole-cell extracts were added at volumes of 10, 5, and 1 μl.