FIG. 7.

Effects of mutations in the internal and external operator sites on the formation of the repressor-operator complex. Addition of different concentrations of purified GntR to the 456-bp gntT fragment gave a mixture containing free DNA (F) and 1:1 (R1) and 2:1 (R2) repressor complexes, respectively. Samples a to i and j to n contained 6 and 2.2 nM gntT DNA, respectively. Samples a to c, d to f, g to i, and j to n contained gntT fragments from strains NP105, NP206, NP1256, and NP220, respectively.