This ribbon-helix-helix domain binds to DNA and may be a part of a toxin-antitoxin system [1].

1: A new member of the ribbon-helix-helix transcription factor superfamily from the plant pathogen Xanthomonas axonopodis pv.citri. Gallo M, Ferrari E, Eliseo T, Amata I, Pertinhez TA, Katsuyama AM, Paci M, Farah CS, Spisni A, Cicero DO; J Struct Biol. 2010;170:21-31. PMID:20060909