ParD is a plasmid anti-toxin than forms a ribbon-helix-helix DNA binding structure [1]. It stabilises plasmids by inhibiting ParE toxicity in cells that express ParD and ParE. ParD forms a dimer and also regulates its own promoter (parDE).

1: The anti-toxin ParD of plasmid RK2 consists of two structurally distinct moieties and belongs to the ribbon-helix-helix family of DNA-binding proteins. Oberer M, Zangger K, Prytulla S, Keller W; Biochem J. 2002;361:41-47. PMID:11743881