Figure 3. Exemplary effects of HbpR A-domain mutations on inducible expression.

Measured fluorescence intensities of Escherichia coli cells carrying a plasmid with a promoterless egfp under control of the HbpR-dependent P_C-promoter in the presence or absence of 20 µM 2-HBP as inducer. EGFP expression was measured on whole cells at two time points and corrected for culture turbidity. Type I to IV correspond to differently shaded entries in Table 1. Note the delayed response in Type II mutants and the higher background in the absence of inducer in type IV mutants.