Figure 3 .

Class I, HilE regulates hilA expression via the post-translational control of HilD. (A) β-Galactosidase activity in strains containing a hilA–lac transcriptional fusion and the indicated mutations after growth under SPI1 inducing conditions. (B) β-Galactosidase activity of strains containing a hilA–lac transcriptional fusion and indicated mutations with rtsA under the control of a tetracycline-regulated promoter. Strains were grown under SPI1-inducing conditions with the indicated tetracycline concentrations. (C) β-Galactosidase activity in strains containing a hilD–lac transcriptional or a hilD’-’lac translational fusion and the indicated mutations after growth under SPI1 inducing conditions. β-Galactosidase activity units are defined as (μmol of ONP formed min⁻¹) × 10⁶/(OD₆₀₀ × ml of cell suspension) and are reported as mean ± SD, where n = 4.