FIG. 7.

Effects of site-directed mutagenesis of the IRUs in the intergenic region between phnF and phnD on gene expression. Changes were introduced into IRU-1 and IRU-2 (see text for details), and effects were monitored as the expression of phnD-lacZ (A) and phnF-lacZ (B) transcriptional fusions. Cells were grown in minimal Sauton's medium containing 100 mM phosphate (open bars) or starved in phosphate-free medium for 2 h (gray bars). The presence of wild-type sequences (+) or site-directed changes (−) in each IRU are shown below the graphs. Results are shown as the means and standard deviations from three independent experiments.