Expression analysis of CC3255 and CC3252 under heavy metal stress. qRT-PCR experiments were performed with total RNA extracted from exponentially growing cells immediately before and following exposure during 30 min to 55 μM potassium dichromate (K2Cr2O7), 55 μM cadmium chloride (CdCl2), 100 μM hydrogen peroxide (H2O2), 50 μM tert-butyl hydroperoxide (tBOOH), 100 μM paraquat or 50 μM diamide. Values represent the fold change in expression of CC3255 and CC3252 genes in parental strain NA1000 (WT) or the sigF mutant strain SG16 (ΔsigF), exposed or not to stress conditions, compared to the parental strain not exposed to stress. Results were normalized using gene CC0088 as the endogenous control, which was constitutively expressed under the conditions analyzed. Data are mean values of two independent experiments; bars represent the standard error. Statistical analysis is shown in Additional file 1: Table S4.