Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5912863 | Plasmid | 2015 | 9 Pages |
â¢Centromere-based incompatibility by high-copy number plasmids arises from ParB titration.â¢Extra centromeres on low-copy number co-resident plasmid do not impair the partition process.â¢Proposal of a new hypothesis for the strong centromere-based incompatibility phenotype.â¢Late replication could prevent random assortment of centromere-carrying co-resident plasmids.
In bacteria, low-copy number plasmids are faithfully segregated at cell division by active partition systems that rely on plasmid-specific centromere sequences. When an identical centromere is present on a second plasmid, faithful partition is impaired causing plasmid loss. Depending on the copy number of the co-resident replicon, several mechanisms have been proposed to account for this centromere-based plasmid incompatibility. To gain further insights into these mechanisms, we analyzed the positioning of the F plasmid in the presence of incompatible low- and high-copy number plasmids carrying the F centromere. Our data are fully compatible with the titration hypothesis when extra-centromeres are present on high-copy number plasmids. Interestingly, our plasmids' localization data revealed that the strong incompatibility phenotype, observed when extra centromeres are present on a partition defective low-copy number plasmid, does not directly result from a partition deficiency as previously proposed. We provide a new and simple hypothesis for explaining the strong incompatibility phenotype based on the timing of replication of low-copy number plasmids.