Effects of Fe-restricted conditions and mtsA and htsA inactivation on Fe3+ ferrichrome uptake and FtsB production. (A). 55Fe3+ radioactivity uptake by wild-type (wt), ftsB, ftsC, mtsA, and htsA mutant strains grown in THY in the absence (solid bars) or presence (slashed bars) of 0.3 mM 2,2'-dipyridyl. The experiment was performed as in Fig. 3. (B) Western blots showing the relative levels of FtsB and PGK as a control in the strains grown under the same conditions as in panel A. Proteins from 1 × 108 bacteria of each strain were probed with mouse anti-FtsB and anti-PGK antisera. The relative levels of FtsB and PGK were obtained by dividing the intensity of each band by the intensity of the FtsB or PGK band of the wild-type strain.