Involved in the cellular response to hydrogen peroxide (H(2)O(2)) stress. During H(2)O(2) stress, prevents oxidative damage to both DNA and proteins by diminishing the amount of unincorporated iron within the cell. Induced by H(2)O(2), via OxyR. In a catalase/peroxidase-deficient (Hpx(-)) background, yaaA deletion mutants grow poorly and form filaments in aerobic medium. Mutants show higher levels of DNA damage and polypeptide damage during H(2)O(2) stress. They also have an unusually high level of intracellular unincorporated iron. Belongs to the UPF0246 family.