FIG. 5.

Regulation of detoxifying enzymes of the cellular antioxidant response in hdaA deletion strains. H4 as a ΔhdaA strain and H1 as a control representing the wt were used. (A) Transcription rates of the coding sequences of superoxide dismutases A and B and catalase B at various concentrations of menadione. Northern analyses were performed with 10 μg of total RNA isolated from strains grown for 18 h in minimal medium and for a further 3 h in the presence of the corresponding MD concentration. Transcripts were detected with digoxigenin-labeled probes specific for the respective sequences. (B) Transcription rates of three catalase genes (catA, catB, and catC) in the presence of different concentrations of H₂O₂. Strains were grown for 18 h in minimal medium and for a further 3 h in the presence of the corresponding H₂O₂ concentration. Ethidium bromide-stained rRNA was used as a quality and loading control in panels A and B. (C) CatB activity in protein extracts from H4 (ΔhdaA) and H1 (wt) growing under conditions as described for panel B. Protein extracts were loaded onto a native polyacrylamide gel, and CatB activities were determined by staining as described in Materials and Methods. As a loading control, aliquots used for the zymogram analysis were loaded onto an SDS-polyacrylamide gel and stained with Coomassie blue (lower panel).