title: Fim operon variation in the emergence of Enterohemorrhagic Escherichia coli: an evolutionary and functional analysis.
abstract: Fim operons were examined to illuminate the emergence of Escherichia coli O157:H7 from the less-virulent E. coli O55:H7. A fim invertible element deletion occurred only after O157:H7 descended from O55:H7, and after sorbitol nonfermenting O157 diverged. Type 1 pili nonexpression correlates with this deletion in all enterohemorrhagic E. coli (EHEC) tested. An N135K FimH mutation in the two most evolved O157:H7 clusters is not found in other EHEC. These data refine the evolutionary history of an emerging pathogen.
authors.affiliation: Washington University School of Medicine, St Louis, MO 63110, USA.
authors.forename: Nurmohammad
authors.initials: N
authors.lastname: Shaikh
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Holt
authors.forename: James R
authors.initials: JR
authors.lastname: Johnson
authors.forename: Phillip I
authors.initials: PI
authors.lastname: Tarr
mesh_terms: D018830:Adhesins, Escherichia coli / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D019453:Escherichia coli O157 / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000502:physiology*; D019143:Evolution, Molecular; D036781:Fimbriae Proteins / Q000235:genetics* / Q000502:physiology*; D008969:Molecular Sequence Data; D009876:Operon; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion
chemical_list: D018830:Adhesins, Escherichia coli; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C058769:fimH protein, E coli; D036781:Fimbriae Proteins