Fig. 1.

Mtb uses heme as an iron source and secretes a heme-binding protein. (A and B) MtbΔmbtB was grown in 7H9–0.01% tyloxapol media containing mycobactin J (myc) (10 ng/mL), heme (Hm), (0.04, 0.2, or 1 μM), human hemoglobin (Hb), (0.04, 0.2, or 1 μM; concentration of the monomer), or no added supplement (0 μM Hm or Hb). Growth was determined by measuring absorbance at 750 nm. Three independent experiments were performed with similar results. (C) SDS/PAGE of Mtb culture filtrate fractions eluted from a hemin–agarose column. Lane 1, molecular weight marker; lane 2, purified recombinant Rv0203; lanes 3 and 4, eluted fractions.