FIG. 5.

(A) Effect of the crr::kan mutation on a set of rpoS-lacZ fusion genes. Strains carrying the three types of rpoS-lacZ genes described for Fig. 1 in either crr⁺ (+) or crr::kan (−) background were grown at 37°C in Luria broth. At the mid-logarithmic phase, β-galactosidase activity was measured. The data are means with standard deviations for four independent assays. OF, operon fusion. (B) Effect of the crr::kan mutation on the half-life of ς^S. Strains CU263 (wild type; open circles) and CU330 (crr::kan; closed circles) were grown at 37°C in Luria broth. At the mid-logarithmic phase, cells were treated with 25 μg of chloramphenicol per ml. At the indicated intervals, cells were harvested and subjected to immunoblotting using anti-ς^S antiserum. The amount of ς^S was expressed relative to that determined for the sample at time zero. (C) Cellular ς^S content in the crr::kan rssB::cam double mutant. Strains carrying the indicated mutations were grown at 37°C in Luria broth. At the mid-logarithmic phase, cells were harvested and subjected to immunoblotting using anti-ς^S antiserum. WT, wild type.