title: Mosaic structure of plasmids from natural populations of Escherichia coli.
abstract: The distribution of plasmids related to the fertility factor F was examined in the ECOR reference collection of Escherichia coli. Probes specific for four F-related genes were isolated and used to survey the collection by DNA hybridization. To estimate the genetic diversity of genes in F-like plasmids, DNA sequences were obtained for four plasmid genes. The phylogenetic relationships among the plasmids in the ECOR strains is very different from that of the strains themselves. This finding supports the view that plasmid transfer has been frequent within and between the major groups of ECOR. Furthermore, the sequences indicate that recombination between genes in plasmids takes place at a considerably higher frequency than that observed for chromosomal genes. The plasmid genes, and by inference the plasmids themselves, are mosaic in structure with different regions acquired from different sources. Comparison of gene sequences from a variety of naturally occurring plasmids suggested a plausible donor of some of the recombinant regions as well as implicating a chi site in the mechanism of genetic exchange. The relatively high rate of recombination in F-plasmid genes suggests that conjugational gene transfer may play a greater role in bacterial population structure than previously appreciated.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: E F
authors.initials: EF
authors.lastname: Boyd
authors.forename: C W
authors.initials: CW
authors.lastname: Hill
authors.forename: S M
authors.initials: SM
authors.lastname: Rich
authors.forename: D L
authors.initials: DL
authors.lastname: Hartl
mesh_terms: D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics*; D001483:Base Sequence; D004265:DNA Helicases; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000145:classification / Q000235:genetics*; D029968:Escherichia coli Proteins; D019143:Evolution, Molecular; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009030:Mosaicism; D009693:Nucleic Acid Hybridization; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics; D011110:Polymorphism, Genetic; D011506:Proteins / Q000145:classification / Q000235:genetics*; D016601:RNA-Binding Proteins; D011995:Recombination, Genetic; D012097:Repressor Proteins; D015534:Trans-Activators
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011506:Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; C045264:replication initiator protein; C064957:traD protein, E coli; C063238:traY protein, E coli; C074275:FinO protein, E coli; D004265:DNA Helicases