title: Comparative analysis of the locus of enterocyte effacement and its flanking regions.
abstract: The attaching-and-effacing (A/E) phenotype mediated by factors derived from the locus of enterocyte effacement (LEE) is a hallmark of clinically important intestinal pathotypes of Escherichia coli, including enteropathogenic (EPEC), atypical EPEC (ATEC), and enterohemorrhagic E. coli strains. Epidemiological studies indicate that the frequency of diarrhea outbreaks caused by ATEC is increasing. Hence, it is of major importance to further characterize putative factors contributing to the pathogenicity of these strains and to gain additional insight into the plasticity and evolutionary aspects of this emerging pathotype. Here, we analyzed the two clinical ATEC isolates B6 (O26:K60) and 9812 (O128:H2) and compared the genetic organizations, flanking regions, and chromosomal insertion loci of their LEE with those of the LEE of other A/E pathogens. Our analysis shows that the core LEE is largely conserved-particularly among genes coding for the type 3 secretion system-whereas genes encoding effector proteins display a higher variability. Chromosomal insertion loci appear to be restricted to selC, pheU, and pheV. In contrast, striking differences were found between the 5'- and 3'-associated flanking regions reflecting the different histories of the various strains and also possibly indicating different lines in evolution.
authors.affiliation: Institut für Infektiologie, Zentrum für Molekularbiologie der Entzündung, Münster, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Müller
authors.forename: Inga
authors.initials: I
authors.lastname: Benz
authors.forename: Ariane
authors.initials: A
authors.lastname: Liebchen
authors.forename: Inka
authors.initials: I
authors.lastname: Gallitz
authors.forename: Helge
authors.initials: H
authors.lastname: Karch
authors.forename: M Alexander
authors.initials: MA
authors.lastname: Schmidt
mesh_terms: D017124:Conserved Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D054324:Enterohemorrhagic Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D054308:Enteropathogenic Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D014644:Genetic Variation; D006801:Humans; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D037521:Virulence Factors / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C457340:LEE protein, E coli; D010750:Phosphoproteins; D037521:Virulence Factors