Localization of the naturally occurring plasmid ColE1 at the cell pole.

The naturally occurring plasmid ColE1 was found to localize as a cluster in one or both of the cell poles of Escherichia coli. In addition to the polar localization of ColE1 in most cells, movement of the plasmid to the midcell position was observed in time-lapse studies. ColE1 could be displaced from its polar location by the p15A replicon, pBAD33, but not by plasmid RK2.

Inhibition of protein and RNA synthesis in Escherichia coli results in declustering of plasmid RK2.

Multi-copy plasmids in Escherichia coli are not randomly distributed throughout the cell but are present as clusters of plasmid molecules that are localized at preferred cellular locations. A plasmid RK2 derivative (pZZ15) that can be tagged with a green fluorescent protein-LacI fusion protein normally exists as clusters that are localized at the mid- and quarter-cell positions. In this study the effect of the protein synthesis inhibitor, chloramphenicol, and the RNA synthesis inhibitor, rifampicin, on RK2 clustering and localization was examined.

Functional analysis of two putative chromosomal replication origins from Pseudomonas aeruginosa.

Two autonomously replicating elements previously isolated from Pseudomonas aeruginosa were characterized in vitro for pre-priming complex formation using combinations of replication proteins from P. aeruginosa and Escherichia coli. The results of these studies showed that the P.

Plasmid host-range: restrictions to F replication in Pseudomonas.

Host-range, a fundamental property of a bacterial plasmid, is primarily determined by the plasmid replication system. To investigate the basis of the restricted host-range of the well-studied F-plasmid of Escherichia coli, we characterized in vitro the interactions of the host DnaA initiation protein and DnaB helicase from Pseudomonas aeruginosa and Pseudomonas putida with the replication origin, oriS, and initiation protein, RepE, of the RepFIA replicon. The results presented here show that a pre-priming complex can form at the F-origin with the replication proteins from the non-native hosts in the presence of RepE.

A specific region in the N terminus of a replication initiation protein of plasmid RK2 is required for recruitment of Pseudomonas aeruginosa DnaB helicase to the plasmid origin.

Broad host range plasmid RK2 encodes two versions of its essential replication initiation protein, TrfA, using in-frame translational starts spaced 97 amino acids apart. The smaller protein, TrfA-33, is sufficient for plasmid replication in many bacterial hosts. Efficient replication in Pseudomonas aeruginosa, however, specifically requires the larger TrfA-44 protein.