This is a putative DNA-binding protein dimerization domain found bacterial proteins such as CD3330, (a transposon-related DNA-binding protein from Clostridium difficile). Crystal structure analysis suggests that CD3330 N-terminus is involved in dimer formation and also in crystal packing but the C-terminus is open to solvent [1].

1: Cleavable C-terminal His-tag vectors for structure determination. Eschenfeldt WH, Maltseva N, Stols L, Donnelly MI, Gu M, Nocek B, Tan K, Kim Y, Joachimiak A; J Struct Funct Genomics. 2010;11:31-39. PMID:20213425