Identification of high-copy-number inhibitors of P1 plasmid stability

grantor: University of TorontoP1 is a low-copy-number plasmid that requires an active partition system for stable maintenance in Escherichia coli. The P1 par operon contains two cotranscribed genes, parA and parB, and a downstream cis-acting site, parS. ParA and ParB are both essential for partition, but overproduction of either protein disturbs partition and destabilizes P1. Partition must position P1 plasmids so that each daughter cell receives one copy. Bacterial host factors are believed to participate in the positioning process. A genetic screen using a high-copy library of E. coli genes was performed to identify host factors, as it was anticipated that overproduction of key host proteins would disrupt the partition process and destabilize P1. I identified ten gene products that destabilize P1 when overproduced, but are not directly required for partition. Subsequent tests were performed to elucidate the functions of these gene products, but their roles in P1 partition remain unknown.M.Sc