Fig. 1.

Molecular components of the B. subtilis iron-sparing response. (A) Organization of the fsrA fbpAB, and fbpC transcription units. FB indicates a Fur box. (B) Northern blot analysis of fsrA expression in different strains. 23S rRNA was used as an internal loading control. (C) Binding of purified Fur to the promoter region of fsrA (0.1 nM) as detected by electrophoretic mobility shift assay. (D) Detection of FLAG-tagged FbpA, FbpB, and FbpC by Western blot with anti-FLAG antibodies. (E) Amino acid sequences and calculated pI of the FbpA, B, and C proteins.