title: High Recombinant Frequency in Extraintestinal Pathogenic Escherichia coli Strains.
abstract: Homologous recombination promotes genetic diversity by facilitating the integration of foreign DNA and intrachromosomal gene shuffling. It has been hypothesized that if recombination is variable among strains, selection should favor higher recombination rates among pathogens, as they face additional selection pressures from host defenses. To test this hypothesis we have developed a plasmid-based method for estimating the rate of recombination independently of other factors such as DNA transfer, selective processes, and mutational interference. Our results with 160 human commensal and extraintestinal pathogenic Escherichia coli (ExPEC) isolates show that the recombinant frequencies are extremely diverse (ranging 9 orders of magnitude) and plastic (they are profoundly affected by growth in urine, a condition commonly encountered by ExPEC). We find that the frequency of recombination is biased by strain lifestyle, as ExPEC isolates display strikingly higher recombination rates than their commensal counterparts. Furthermore, the presence of virulence factors is positively associated with higher recombination frequencies. These results suggest selection for high homologous recombination capacity, which may result in a higher evolvability for pathogens compared with commensals.
authors: Instituto de Biomedicina de Sevilla (IBIS)-CSIC, Sevilla, Spain Centro Nacional de Biotecnología-CSIC, Madrid, Spain.
authors: Jerónimo
authors: J
authors: Rodríguez-Beltrán
authors: INSERM, IAME, UMR 1137, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France Assistance Publique-Hôpitaux de Paris, Groupe Hospitalier Pitié-Salpêtrière Charles Foix; Université Pierre et Marie Curie, Paris, France.
authors: Jérôme
authors: J
authors: Tourret
authors: INSERM, IAME, UMR 1137, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors: Olivier
authors: O
authors: Tenaillon
authors: Servicio de Microbiología, Hospital Universitario La Paz, IdiPaz, Madrid, Spain.
authors: Elena
authors: E
authors: López
authors: INSERM, IAME, UMR 1137, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors: Emmanuelle
authors: E
authors: Bourdelier
authors: Instituto de Biomedicina de Sevilla (IBIS)-CSIC, Sevilla, Spain Centro Nacional de Biotecnología-CSIC, Madrid, Spain.
authors: Coloma
authors: C
authors: Costas
authors: INSERM U1001, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France.
authors: Ivan
authors: I
authors: Matic
authors: INSERM, IAME, UMR 1137, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors: Erick
authors: E
authors: Denamur
authors: Instituto de Biomedicina de Sevilla (IBIS)-CSIC, Sevilla, Spain Centro Nacional de Biotecnología-CSIC, Madrid, Spain jblazquez-ibis@us.es.
authors: Jesús
authors: J
authors: Blázquez
mesh_terms: D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity*; D005798:Genes, Bacterial; D059765:Homologous Recombination / Q000235:genetics*; D007422:Intestines / Q000382:microbiology*; D016296:Mutagenesis / Q000235:genetics; D059645:Mutation Rate; D014774:Virulence / Q000235:genetics
keywords: ExPEC; RecA; commensal; evolution; homologous recombination