Fig. 6. Regulation of the operon.

a, b qRT-PCR analyses of the parental and the cueR KO strains treated for 30 min with 2 mM CuSO₄ (a) or 10 mM H₂O₂ (b), showing the expression levels of prxgrx relative to untreated controls. Data were normalized with the housekeeping gene bp3416. Three biological replicates were performed. (c) EMSA with recombinant OxyR and DNA fragments of the cueR-copZ and copZ-prxgrx intergenic regions, IGR 1 and IGR 2, respectively. The uncropped gel is shown in Supplementary Figure S10. (d) Schematic representation of the locus, with sequences of the putative CueR and OxyR boxes. The site of transcription initiation was determined by 5’RACE (Supplementary Figure S5). The putative OxyR binding sites were identified by their similarity with the E. coli consensus sequences, and alignments of the Bordetella and Achromobacter sequences were used to build the consensus motif (Supplementary Figure S11).