Cg-OxyR oxidation decreases binding affinity and extension to the catalase promoter region. Cg-OxyR oxidation decreases binding affinity and extension to the catalase promoter region. (A) DNase I footprint of the C. glutamicum catalase promoter/operator region in presence of WT or C206S/C215S CgOxyR, and under reducing (Left) or oxidizing (Right) conditions. A C/T and A/G sequencing ladder and a no Cg-OxyR control were added in each condition. Binding regions are highlighted in blue, with the binding affinity being proportional to the color intensity. The nucleotides that are hypersensitive to DNase I treatment in presence of OxyR are marked by a green dot. The transcription start point (+1) is highlighted in red, and the −10 region is highlighted in salmon. A summary of the binding experiments is shown below. (B) Fluorescence polarization experiments using a 6-FAM–labeled oligonucleotide containing the catalase binding region (highlighted in gray in A). The labeled oligonucleotide was mixed with increasing concentrations of WT/C206S Cg-OxyR, under reducing or oxidizing conditions, until reaching binding saturation (n = 3). Brandán Pedre et al. PNAS doi:10.1073/pnas.1807954115 ©2018 by National Academy of Sciences