FIG. 4.
σGE156K is less susceptible to SpoIIAB in vivo than wild-type σG. (A) B. subtilis strains AH2492 (PxylA-spoIIIG Pspac-spoIIAB sspE-lacZ) (circles) and AH2493 (PxylA-spoIIIGE156K Pspac-spoIIAB sspE-lacZ) (squares) were grown in LB medium with 1 mM IPTG (closed symbols) to induce spoIIAB expression or in the absence of inducer (open symbols). OD (600 nm), optical density at 600 nm. (B) Samples were taken at the indicated times and assayed for β-galactosidase production. From left to right, the four bars for each time point show the results for strain AH2492 grown in the absence of IPTG (white bars), AH2492 grown in the presence of IPTG (black bars), AH2493 grown in the absence of IPTG (light grey bars), and AH2493 grown in the presence of IPTG (dark grey bars). (C) Ratio between the activity of σG (black bars) or σGE156K (white bars) in the absence and presence of IPTG (expressed as a percentage).