FIG. 3.
Regulation of fHBP by FNR. (A) Northern blot analysis showing the regulation of mRNA transcripts. The generation of the null mutants and Δfnr complemented strain ΔfnrC (in the MC58 and H44/76 background) and their growth under aerobic (+) and oxygen-limiting (−) conditions are described in Materials and Methods. Aliquots (5 μg) of total RNA were subjected to electrophoresis, transferred onto nylon filters, and hybridized with the fhbp-specific probe. In each lane, the amount of RNA loaded was normalized to the amount of rRNA. (B) Western blot analysis showing the FNR-regulated protein expression. Equal amounts of total protein from overnight plates cultured under microaerobic conditions were fractionated by SDS-PAGE, blotted onto nitrocellulose filters, and stained with mouse polyclonal antiserum raised against the NMB1869 protein, the fHBP protein, or the FNR protein. Where IPTG was necessary to induce the expression of FNR, it was added to plates at a final concentration of 1 mM.