Role of Intraspecies Recombination in the Spread of Pathogenicity Islands within the Escherichia coli Species

PLoS Pathogens

Pierre Darlu¹  Ivan Matic²  Olivier Tenaillon³  Erick Denamur³  Olivier Clermont³  Kirsten Weinert⁴  Giuseppe Magistro⁴  Christiane Hoffmann⁴  Andreas Wieser⁴  Sören Schubert⁴ 

[1] INSERM U535, Hôpital Paul Brousse, Villejuif, France;INSERM U571 and Université Paris 5, Paris, France;INSERM U722 and Université Paris 7, Paris, France;Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Munich, Germany

关键词: Phylogenetic analysis;    Phylogenetics;    Transfer RNA;    Bacterial evolution;    Bacterial genomics;    Horizontal gene transfer;    Bacterial pathogens;    Genetic loci;   

DOI  :  10.1371/journal.ppat.1000257

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Horizontal gene transfer is a key step in the evolution of bacterial pathogens. Besides phages and plasmids, pathogenicity islands (PAIs) are subjected to horizontal transfer. The transfer mechanisms of PAIs within a certain bacterial species or between different species are still not well understood. This study is focused on the High-Pathogenicity Island (HPI), which is a PAI widely spread among extraintestinal pathogenic Escherichia coli and serves as a model for horizontal transfer of PAIs in general. We applied a phylogenetic approach using multilocus sequence typing on HPI-positive and -negative natural E. coli isolates representative of the species diversity to infer the mechanism of horizontal HPI transfer within the E. coli species. In each strain, the partial nucleotide sequences of 6 HPI–encoded genes and 6 housekeeping genes of the genomic backbone, as well as DNA fragments immediately upstream and downstream of the HPI were compared. This revealed that the HPI is not solely vertically transmitted, but that recombination of large DNA fragments beyond the HPI plays a major role in the spread of the HPI within E. coli species. In support of the results of the phylogenetic analyses, we experimentally demonstrated that HPI can be transferred between different E. coli strains by F-plasmid mediated mobilization. Sequencing of the chromosomal DNA regions immediately upstream and downstream of the HPI in the recipient strain indicated that the HPI was transferred and integrated together with HPI–flanking DNA regions of the donor strain. The results of this study demonstrate for the first time that conjugative transfer and homologous DNA recombination play a major role in horizontal transfer of a pathogenicity island within the species E. coli.

【 授权许可】

CC BY