Bacterial plasmids that carry two functional centromere analogs are stable and are partitioned faithfully.

The par genes of unit-copy plasmids P1 and F promote equitable distribution of plasmid copies to daughter cells and can be considered to be functional analogs of eucaryotic centromeres. Composite plasmids were constructed which carry either two functional P1 par regions or one F and one P1 region. Unlike dicentric chromosomes, such plasmids are stably maintained.