Fig. 6. Transcripton of pbgP in a strain grown in low magnesium expressing the constitutive pmrA505 allele is independent of pmrD. β-galactosidase activities (Miller units) expressed by transformants grown in N-minimal medium pH 7.7 with 10 µM Mg²⁺ (A), 10 µM Mg²⁺ and 100 µM Fe²⁺ (B) or 10 mM Mg²⁺ (C) were determined for a mutant harboring a lac transcriptional fusion to pbgP. The transcriptional activity was investigated in four genetic backgrounds: wild type, pmrD, pmrA505 and pmrD pmrA505. The data correspond to mean values of four independent experiments performed in duplicate. Error bars correspond to the standard deviation (and are only shown if greater than the resolution of the figure).