Promotes the biosynthesis of heme as well as the assembly and repair of iron-sulfur clusters by delivering Fe(2+) to proteins involved in these pathways. Plays a role in the protection against iron-catalyzed oxidative stress through its ability to catalyze the oxidation of Fe(2+) to Fe(3+). Can store large amounts of the metal in the form of a ferrihydrite mineral by oligomerization. May be involved in regulation of the mitochondrial electron transport chain. 4 Fe(2+) + 4 H(+) + O2 = 4 Fe(3+) + 2 H2O Monomer; increments in mitochondrial iron uptake induce stepwise assembly of species ranging from trimers to 24-mers. Interacts with ISU1. Interacts with YHB1, SDH1, SDH2, AIM45 and CIR1. Processed in two steps by mitochondrial processing peptidase (MPP). MPP first cleaves the precursor to intermediate form and subsequently converts the intermediate to mature size protein. Present with 1560 molecules/cell in log phase SD medium. Belongs to the frataxin family.