FIG. 7.

DNase I footprinting analysis of direct-repeat mutants. The labelled plasmid templates used in this experiment were the wild-type plasmid pJIR1546 (lanes 1 and 2) and the mutated derivatives pJIR1804 (DR1 mutant; lanes 3 and 4), pJIR1803 (DR2 mutant; lanes 5 and 6), and pJIR1821 (DR1-DR2 double mutant; lanes 7 and 8). Lanes 1, 3, 5, and 7, control reaction mixtures that were not preincubated with VirR. Lanes 2, 4, 6, and 8, test reaction mixtures that were incubated with 2 μg of VirR prior to partial digestion by DNase I and electrophoresis. The first four lanes (ACGT) show the sequencing reaction products from the wild-type pJIR1546 template. Lanes 9 to 11, C track sequencing reaction products from pJIR1804, pJIR1803, and pJIR1821, respectively. The positions of the DR1 and DR2 repeats are shown by the arrows, and the region of protection is represented by the open rectangle. The −10 and −35 boxes are depicted as black rectangles, and the transcription start point is shown as +1.