Uncharacterized diverse domain family with conserved DGQHR motif, in addition to QR and FXXXN motifs. Some proteins have been identified as parts of DNA phosphorothioation systems. Related to dndB, which acts in the regulation of DNA modifications, including DNA phosphorothioation. These proteins show similarity to the N-terminal domain of ParB, a DNA-binding component of the prokaryotic parABS partitioning system, and other members of the ParB/Srx superfamily.