FIG. 4.

Nucleotide replacements in the CDR2 DRE. (A) Possibility of base replacement in the DRE core sequence. For each position, the growth conferred in MM supplemented with estradiol (10 μg/ml) by the base(s) replacing the wild-type nucleotide is indicated. −, the reporter system is nonfunctional, meaning that the strain containing it is unable to grow in the presence of estradiol or shows constitutive growth even in the absence of estradiol; +, the reporter system is functional, meaning that the growth of the associated strain is identical to that of the positive control carrying wild-type DRE (DSY2673); +/−, reduced growth compared to the positive control. (B) Growth of reporter strains carrying DREs with systematic nucleotide replacement in the P_(CDR2)-HIS3 reporter system. Serial dilutions of overnight cultures were plated onto MM supplemented with histidine (his) or with estradiol. Nucleotide positions in the DRE and replacements are indicated. Plates were incubated for 48 h at 34°C. Each strain spotted is representative of three transformants. WT, wild type.