This protein family includes DraIII from Deinococcus radiophilus, a type IIP restriction endonuclease that recognises a gapped double-stranded DNA sequence and nicks creating a double strand break with a three base 3' overhang. DraIII adopts a homodimeric configuration. Each monomer shows a beta-beta-alpha-metal fold in the C terminus, where the HNH active site is located. It also has two zinc- and one magnesium-binding sites [1].

1: Elimination of inter-domain interactions increases the cleavage fidelity of the restriction endonuclease DraIII. Zhuo W, Lai X, Zhang L, Chan SH, Li F, Zhu Z, Yang M, Sun D; Protein Cell. 2014;5:357-368. PMID:24733184