title: Identification of the origin of replications and partial characterization of plasmid pRK100.
abstract: In search for the evolutionary origin of the conjugative F-like plasmid pRK100, the plasmid's functional replication regions were identified. Additionally targeted genetic analysis was used to investigate origins of other regions of the plasmid. Construction of minireplicons via ligation of Tn1725 with plasmid fragments and targeted cloning of putative replication regions, followed by sequence analysis indicated two functional replication regions, a F plasmid related RepFIB and a R1 plasmid related RepFIIA replication region. Partial nucleotide sequencing of regions of the plasmid revealed genes that encode a putative enterochelin iron uptake system previously associated with an Escherichia coli pathogenicity island, PAI III536, and the pColV-like aerobactin genes. In addition, a homologue of the R100 plasmid related rmoA gene was found that exhibits strong similarity to hha/ymoA encoding the Hha/YmoA class of modulators of gene expression. PCR and hybridization experiments further demonstrated that pRK100 harbors multiple IS2 and IS3 insertion sequences that may have facilitated in the acquisition of elements from other DNA molecules. These data together with the previous identification of a F-like tra region and a pColIa-like colicin Ia, indicate that pRK100 has a highly mosaic structure with elements derived from many different known large natural plasmids.
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia.
authors.forename: Marjanca
authors.initials: M
authors.lastname: Starcic Erjavec
authors.forename: Wim
authors.initials: W
authors.lastname: Gaastra
authors.forename: Jos
authors.initials: J
authors.lastname: van Putten
authors.forename: Darja
authors.initials: D
authors.lastname: Zgur-Bertok
mesh_terms: D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D018741:Replication Origin / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D004251:DNA Transposable Elements