The parABS system is a broadly conserved molecular mechanism for plasmid partitioning and chromosome segregation in bacteria.
Originally identified as a genetic element required for faithful partitioning of low-copy-number plasmids, it consists of three components: the ParA ATPase, the ParB DNA-binding protein, and the cis-acting parS sequence.
[1] Based on chromatin immunoprecipitation (ChIP) experiments, ParB has the ability to bind not only to high-affinity parS sites but also to adjacent nonspecific DNA, a behavior known as "spreading".
[6][7] The ParB-DNA complex binds to ATP-bound ParA,[8] stimulating its ATPase activity and its dissociation from DNA.
[9] This translocation mechanism has been observed by fluorescence microscopy both in vivo and more recently in vitro with purified components.