Figure 8
The heme/hemoglobin binding protein, Spbhp-37, plays a role in mediating the positive impact of hemoglobin in Spn. Fresh medium was inoculated with D39 (blue) and the isogenic Δspbhp-37 strain (orange) grown on BAPs (18 h, starting O.D.600 = 0.05). Shown is growth in (A) THYB with 3 mM 2, 2′-Dipyridyl (DP), THYB with DP and 10 μM heme (triangles) or 20 μM hemoglobin (circles), or (B) THYB (empty symbols) or THYB with 20 µM hemoglobin (full symbol). The data are representative of three independent experiments performed in triplicates; error bars indicate SD. (C) Total intracellular iron content (ppm) determined by ICP-MS in D39 wild type and Spbhp-37 mutant cultures samples (normalized to optical density) grown in THYB with 20 µM hemoglobin. The data represents the average of three independent biological replicates; error bars indicate SD. (D) Fold change in gene expression in the wild type and Δspbhp-37 strains 2 h post hemoglobin treatment relative to the control (saline) as determined by qRT-PCR. The experiments were performed in duplicates with at least two biological replicates. The replicates data are shown as the mean ± SD. The asterisks denote statistical significance, P ≤ 0.05 (WT vs. MT, Student's t-test).
