title: Characterization and evidence of mobilization of the LEE pathogenicity island of rabbit-specific strains of enteropathogenic Escherichia coli.
abstract: We have characterized the LEE pathogenicity islands (PAIs) of two rabbit-specific strains of enteropathogenic E. coli (REPEC), 83/39 (serotype O15:H-) and 84/110-1 (O103:H2), and have compared them to homologous loci from the human enteropathogenic and enterohaemorrhagic E. coli strains, E2348/69 and EDL933, and another REPEC strain, RDEC-1. All five PAIs contain a 34 kb core region that is highly conserved in gene order and nucleotide sequence. However, the LEE of 83/39 is significantly larger (59 540 basepairs) than those of the human strains, which are less than 44 kb, and has inserted into pheU tRNA. The regions flanking the 34 kb core of 83/39 contain homologues of two putative virulence determinants, efa1/lifA and senA. The LEE of 84/110-1 is approximately 85 kb and is located at pheV tRNA. Its core is almost identical to those of 83/39 and RDEC-1, apart from a larger espF gene, but its flanking regions contain trcA, a putative virulence determinant of EPEC. All three REPEC LEE PAIs contain a gene for an integrase, Int-phe. The LEE PAI of 84/110-1 is also flanked by short direct repeats (representing the 3'-end of pheV tRNA), suggesting that it may be unstable. To investigate this possibility, we constructed a LEE::sacB derivative of 84/110-1 and showed that the PAI was capable of spontaneous deletion. We also showed that Int-phe can mediate site-specific integration of foreign DNA at the pheU tRNA locus of E. coli DH1. Together these results indicate possible mechanisms of mobilization and integration of the LEE PAI.
authors.affiliation: Department of Microbiology and Immunology, University of Melbourne, Australia.
authors.forename: Marija
authors.initials: M
authors.lastname: Tauschek
authors.forename: Richard A
authors.initials: RA
authors.lastname: Strugnell
authors.forename: Roy M
authors.initials: RM
authors.lastname: Robins-Browne
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000032:analysis; D020895:Enterocytes / Q000382:microbiology / Q000473:pathology; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000473:pathology; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000502:physiology; D017353:Gene Deletion; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D010750:Phosphoproteins; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics; D011817:Rabbits; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D022603:Shiga Toxins / Q000096:biosynthesis / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C457340:LEE protein, E coli; D010750:Phosphoproteins; D012345:RNA, Transfer, Amino Acid-Specific; D022603:Shiga Toxins