FIGURE 7.

Manganese import (by MntH) and iron sequestration (by Dps) are key elements in protecting PDF, TDH, and CDA from H₂O₂. A–C, PDF, TDH, and CDA activities in wild-type (MG1655, WT), Hpx⁻ (LC106), Hpx⁻ ΔmntH (AA30), and Hpx⁻ Δdps (SP66) strains. Where indicated, extra manganese was included in the growth medium. Assays were conducted after anaerobic reconstitution with nickel (PDF) or iron (TDH and CDA). Time courses of PDF and TDH inactivation are shown as supplemental Fig. S2. D, overexpression of PDF relieves the Hpx⁻ ΔmntH growth defect. At time 0, anaerobic cultures were diluted into aerobic medium. The strains used were LC106 (Hpx⁻, circles), AA30 (Hpx⁻ ΔmntH, squares), and SP66 (Hpx⁻ Δdps, diamonds). Closed symbols, plasmid overexpressing PDF; open symbols, vector control.