FIG. 7.
Effect of promoter deletions on antibiotic induction. Serial 5′ and 3′ deletions of the 211-bp sequence immediately upstream of the translational start site of iniB were fused to the lacZ gene in the integrating plasmid pCV125 and transformed into M. smegmatis strain mc2155. (A) Schematic of promoter deletions and induction after 4 h of treatment with either INH (100 μg/ml) or ethambutol (EMB; 5 μg/ml). The dotted line indicates the position of a 19-bp spacer that is unrelated to the sequence it replaced; induction represents mean results from at least three experiments. Numbering corresponds to the distance from the translational start site. (B) β-Galactosidase activity of promoter deletions without (grey) or with (black) 4 h of incubation with INH (100 μg/ml). Values represent means of at least three experiments. Error bars represent 95% confidence intervals.