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 (By similarity). Dps binds the chromosome non-specifically, forming a highly ordered and stable dps-DNA co-crystal within which chromosomal DNA is condensed and protected from diverse damages. Soluble dps might function in iron homeostasis under high iron concentration, while the dps-DNA complex might associate with the protection of DNA from oxidative stress at low iron concentration. Has a weak catalase activity in vitro. 2 Fe(2+) + 2 H(+) + H2O2 = 2 Fe(3+) + 2 H2O Binds 1 heme per molecule. Homohexamer. The dps-DNA complex is found in the cytoplasm whereas a soluble dps is localized preferentially to the thylakoid membrane and is also found in the cell envelope. The dps-DNA complex accumulates during stationary phase and under nitrogen, sulfur, and phosphate stress, but not under iron limitation. Belongs to the Dps family.