A novel hemerythrin DNase from the nitrogen-fixing cyanobacterium Anabaena sp. strain PCC7120

► Alr3199 is functionally active as a DNase or Nickase depending on nature and concentration of cation present. ► Alr3199 has no domain homology with DNase/nicking endonuclease, but has two hemerythrin domains in the C-terminus. ► DNase/Nickase activity of Alr3199 resides in the N-terminal non-hemerythrin region and is modulated by Fe2+ bound to the C-terminal hemerythrin region. ► Alr3199 is the only hemerythrin protein known to have a DNase activity.