ParB N-terminal domain and sulfiredoxin protein-related families
The ParB N-terminal domain/Sulfiredoxin (Srx) superfamily contains proteins with diverse activities. Many of the families are involved in segregation and competition between plasmids and chromosomes. Several families share similar activities with the N-terminal domain of ParB (Spo0J in Bacillus subtilis), a DNA-binding component of the prokaryotic parABS partitioning system. Also within this superfamily is sulfiredoxin (Srx; reactivator of oxidatively inactivated 2-cys peroxiredoxins), RepB N-terminal domain (plasmid segregation replication protein B like protein), nucleoid occlusion protein, KorB N-terminal domain partition protein of low copy number plasmid RK2, irbB (immunoglobulin-binding regulator that activates eib genes), N-terminal domain of sopB protein (promotes proper partitioning of F1 plasmid), fertility inhibition factors OSA and FiwA,DNA sulfur modification protein DndB, and a ParB-like toxin domain. Other activities includes a StrR (regulator in the streptomycin biosynthetic gene cluster), and a family containing a Pyrococcus furiosus nuclease and putative transcriptional regulators sbnI (Staphylococcus aureus siderophore biosynthetic gene cluster ). Nuclease activity has also been reported in Arabidopsis Srx.