PARTITION OF NONREPLICATING DNA BY THE PAR SYSTEM OF BACTERIOPHAGE-P1

P1 plasmid encodes a cis-acting centromere analog, parS, and two Par proteins that together stabilize plasmids by partitioning them to daughter bacteria. We infected immune bacteria with bacteriophage X into which parS had been inserted. The presence of P1 Par proteins in the infected cells,vas found to delay the appearance of cells cured of the nonreplicating, extrachromosomal lambda-parS DNA. This stabilization of lambda-parS, approximated in a computer simulation, demonstrates that active partition by the P1 par system does not require the act of plasmid replication and can be studied in its absence.