Protects DNA from oxidative damage by sequestering intracellular Fe(2+) ion and storing it in the form of Fe(3+) oxyhydroxide mineral. One hydrogen peroxide oxidizes two Fe(2+) ions, which prevents hydroxyl radical production by the Fenton reaction. Required for the survival in the presence of oxidative stress. Dps is also a virulence factor that activates neutrophils, mast cells and monocytes. It binds to neutrophil-glycosphingolipids and to sulfated carbohydrates on mucin. It might have a role in the accumulation of neutrophils and monocytes at the site of infection. Induces superoxide anion generation, adhesion and chemotaxis of neutrophils, through a pertussis toxin-sensitive pathway involving MAP kinases.