FIG. 4.

Effects of wild-type σ⁷⁰ and some σ⁷⁰ mutants on the Fnr-mediated expression of the P_N::lacZ fusion in E. coli. E. coli PK3300 cells harboring plasmid pBBR5P_N (P_N::lacZ) and either plasmid pGEX-2T σ⁷⁰ (WT), pGEX-2Tσ⁷⁰(EA591)(EA591), pGEX-2Tσ⁷⁰(KA593)(KA593), or pGEX-2Tσ⁷⁰(KA597)KA597) (Table 1) were grown anaerobically for 10 h in M63 minimal medium containing 20 mM glycerol in the presence of 20 μg/ml tryptophan to an A₆₀₀ of 0.4. β-Galactosidase activity is shown as the percentage of β-galactosidase activity with respect to that of cells containing wild-type σ⁷⁰ (370 Miller units). The results of one experiment are shown, and the values were reproducible in three independent experiments with standard deviations of <10%.