Destroys radicals which are normally produced within the cells and which are toxic to biological systems. Destroys mitochondrial radicals produced by oxidative stress. Destroys cytoplasmic radicals produced in low copper environments; a condition which inactivates the cytoplasmic copper-dependent superoxide dismutase SOD1. 2 H(+) + 2 superoxide = H2O2 + O2 Binds 1 Mn(2+) ion per subunit. Localizes to the mitochondrion both in copper-replete and copper-limiting conditions. Repressed when copper levels are low in a CUF1-dependent manner (at protein level). Decreases cellular superoxide dismutase activity (PubMed:16524904). Sensitive to thermal stress, and menadione (induces oxidative stress) (PubMed:33567338). Decreases virulence in a mouse model of infection (PubMed:33567338). Belongs to the iron/manganese superoxide dismutase family.