Figure 6.

Induction of the TetR variants by tetracycline (tc), anhydro-tetracycline (atc) and doxycycline (dox). β-Gal activity was determined in the E. coli screening strain with TetR variants encoded by pWH527-derivatives. β-Gal activities are given in Miller Units (MU) with the maximal expression in the absence of TetR (w/o TetR, black bar). White bars show the expression levels obtained with the TetR variant indicated at the bottom. Light gray bars indicate the β-Gal activities after induction with 0.2 μg/ml tc, gray bars after induction with 0.2 μg/ml atc and dark gray bars after induction with 0.2 μg/ml dox.