ParB is a component of the par system which mediates accurate DNA partition during cell division. It recognises A-box and B-box DNA motifs. ParB forms an asymmetric dimer with 2 extended helix-turn-helix (HTH) motifs that bind to A-boxes. The HTH motifs emanate from a beta sheet coiled coil DNA binding module [1]. Both DNA binding elements are free to rotate around a flexible linker, this enables them to bind to complex arrays of A- and B-box elements on adjacent DNA arms of the looped partition site [1].

1: Structures of ParB bound to DNA reveal mechanism of partition complex formation. Schumacher MA, Funnell BE; Nature. 2005;438:516-519. PMID:16306995