FIG. 5.
Effect of iron limitation on phosphatase activity. (A) Phosphatase activities were measured for the WT and the pvdL mutant (PF-B582) after supplementation of cultures with different amounts of the iron chelator 2,2′dipyridyl. The strains were grown in Pi-limiting medium (K10Tπ) for 6 h, with dipyridyl added after 3 h. Growth of the strains was not affected until the addition of 0.3 mM dipyridyl (data not shown). Standard errors calculated from three replicates are shown. (B) phoX transcription in response to iron limitation. The luciferase fusion to phoX was measured for the WT and the PF-B582 (pvdL) and ΔphoB mutants with and without the addition of 0.2 mM 2,2′dipyridyl. Cells were cultured in Pi-limiting medium (K10Tπ) for 6 h. Standard errors were calculated from three replicates.