Fig. 6

Bidirectional expression from pFCF2. Iron-controlled expression from the anti-clockwise-oriented KanR gene in pFCF2 was determined by bacterial growth studies. Shown are normalized cell densities (A₆₀₀) of E. coli entA ⁻ strains transformed with pFCF2-entA grown in (left to right): M9 medium + 2,2'-dipyridyl supplemented with tetracycline; M9 medium + 2,2'-dipyridyl supplemented with tetracyline and kanamycin; LB medium + FeSO₄ supplemented with tetracycline; LB medium + FeSO₄ supplemented with tetracycline and kanamycin. Error bars represent standard deviations from mean values (n=3)