Figure 2

Expression levels from pFS7 for different variants of xylS with silent mutations. Relative expression levels from Pm (measured as maximum ampicillin tolerance at 1 mM m-toluate) are given in grey (error bars = lowest ampicillin concentrations in test on which no growth was observed) and relative luciferase activity as a measure for XylS amounts in black (values from at least two biological replicas). All values (relative ampicillin tolerance and luciferase expression) refer to those of wild type XylS (tolerating 350 μg mL^-1), which are both arbitrarily set to 1. Mutations in the variants (1 to 9), the number stands for the base position that has been changed, relative to the translational start site, the character tells the base in the variant. 1: 6- > C; 2: 13- > C; 3: 15- > G; 4: 16- > C; 5: 27- > G; 6: 30- > C; 7: 36- > T; 8: 42- > T; 9: all of the eight mutations.