Interaction of P1 Plasmid Partition Components with the Bacterial Chromosome

P1 is a low copy number plasmid that uses a dedicated partition system that actively ensures each daughter cell inherits a copy of the plasmid. P1 plasmid partition is a positioning reaction, ensuring that each plasmid copy is correctly localized to the one-quarter and three-quarter position or midcell in an E. coli cell prior to partition. The factors involved in this positioning process are not well understood. I utilized cell biology techniques and E. coli mukB mutants that produce cells with chromosomal condensation defects to study the role of the bacterial chromosome and P1 ParA as possible localization signals. P1 plasmid prefers to localize to the bacterial nucleoid even when the chromosome is perturbed. ParA is necessary for plasmid localization to the chromosome. In this study, live cell microscopy analysis of ParA indicates that an interaction between P1 ParA and the E. coli nucleoid may underlie the localization mechanism of the plasmid partition system.MAS