The HhH domain is a short DNA-binding domain [2].

1: The helix-hairpin-helix DNA-binding motif: a structural basis for non-sequence-specific recognition of DNA. Doherty AJ, Serpell LC, Ponting CP; Nucleic Acids Res 1996;24:2488-2497. PMID:8692686

2: Structural biochemistry of a bacterial checkpoint protein reveals diadenylate cyclase activity regulated by DNA recombination intermediates. Witte G, Hartung S, Buttner K, Hopfner KP; Mol Cell. 2008;30:167-178. PMID:18439896