FIG. 7.

Effects of σ³² overexpression on cellular levels of HilA and HilD proteins and hilA and hilD transcripts. (A) Cultures of strains CS3072 (p) and CS3586 (prpoH⁺) were grown in L broth to an OD₆₀₀ of 0.5 at 37°C, followed by the induction of σ³² with 200 μM IPTG for 1 h. Whole-cell lysates were separated on an SDS-10% polyacrylamide gel and then subjected to immunoblotting with anti-σ³², anti-HilD, and anti-HilA sera. (B) Cultures of strains used in panel A were grown in L broth to an OD₆₀₀ of 0.5 at 37°C, followed by the induction of σ³² with 200 μM IPTG for 30 min. The levels of hilD and hilA transcripts were measured by quantitative real-time RT-PCR and then normalized to 16S rRNA gene expression. The values represent the means and standard deviations of n-fold changes in comparison with the transcription levels of the corresponding genes in CS3072. (C) Cultures of strains CS3593 (Δlon/p) and CS3596 (Δlon/prpoH⁺) were grown in L broth to an OD₆₀₀ of 0.5 at 37°C, followed by incubation with 200 μM IPTG for 1 h to induce σ³². Whole-cell lysates were separated on an SDS-10% polyacrylamide gel and then subjected to immunoblotting analysis. p, pUE212-1; prpoH⁺, pUE212-1-rpoH.