Fig. 3: Gp1 represses SOS-independent promoter P2.

Bar charts illustrating the ß-galactosidase activity in GIL01-cured GBJ002, GIL01 lysogen GBJ002(GIL01), or gp1-expressing GBJ002(pDG1), carrying the following promoter–lacZ fusions: A wild-type P1⁺P2⁺ promoter region, B P1⁺P2⁺ (Δop1) with partial deletion of the gp1 nucleation site, C P1⁺P2^- with mutated -10 promoter element in P2, and D P1^-P2⁺ with mutated -10 promoter element in P1. Isopropyl β-D-1-thiogalactopyranoside (IPTG; 0.1 mM) was added to the strains harboring the pDG148 plasmid derivatives to induce the expression of gp1 upon inoculation, and the activity of the different promoter–lacZ fusions was measured in the absence (white) or presence (gray) of MMC (50 ng mL^-1) 1 h after its addition to bacterial cultures in early exponential phase. Data are presented as bar charts with data points overlap of three independent replicates (n = 3). Upper line of the bar chart represents the mean value and the error bar represents the data range within the 1.5 interquartile range. The statistical significance of the data was assessed using Fisher’s Least Significant Difference (LSD) test.