Regulation of PdpA expression by iron and transcriptional regulators. (a) Levels of PdpA, PdpB and IglB protein expression were determined in mglA and mglB mutant backgrounds. (b) Expression of these proteins, as well as IglC, was also determined in varying iron conditions. The relative level of fluorescence signal generated by reactivity of anti-PdpA, anti-PdpB, anti-IglB, or anti-IglC monoclonal antibodies, calculated as described in Methods, is indicated. The amount of sample loaded to the wells of each polyacrylamide gel was normalized by protein content. The reactivity of a non-specific, cross-reactive protein band is shown in the bottom panel. Results are representative of experiments performed in triplicate.