Premium
A plasmid‐encoded type IV fimbrial gene of enteropathogenic Escherichia coli associated with localized adherence
Author(s) -
Donnenberg M. S.,
Girón J. A.,
Nataro J. P.,
Kaper J. B.
Publication year - 1992
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1992.tb02210.x
Subject(s) - biology , plasmid , escherichia coli , microbiology and biotechnology , enteropathogenic escherichia coli , gene , enterobacteriaceae , genetics
Summary Enteropathogenic Escherichia coli (EPEC) form adherent microcolonies on the surface of tissue culture cells in a pattern termed localized adherence. Localized adherence requires the presence of a large EPEC adherence factor (EAF) plasmid. Recently a bundle‐forming pilus has been described in EPEC possessing the EAF plasmid. An analysis of 22 non‐invasive EPEC Tn phoA mutants revealed that seven have insertions in the EAF plasmid and are incapable of localized adherence. We report here the mapping of the Tn phoA insertions in these mutants. The nucleotide sequence of the gene interrupted in these TnphoA mutants ( bfpA ) was determined and found to correspond to the N ‐terminal amino acid sequence of the major structural protein of the bundle‐forming pilus. The bfpA gene bears sequence similarities to members of the type IV fimbrial gene family and encodes a potential site for processing by a prepilin peptidase. A plasmid containing bfpA as the only open reading frame directs the synthesis of a protein recognized by antiserum raised against the bundle‐forming pilus. Tn phoA mutants at this locus are unable to synthesize BfpA, but synthesis is restored by introduction of a plasmid containing the cloned gene. The minimum fragment of DNA required to restore localized adherence is considerably greater than that required to restore BfpA synthesis. BfpA expression, as assessed by alkaline phophatase activity in bfpA ::Tn phoA mutants, is affected by temperature and growth medium. These studies describe an EPEC plasmid‐encoded fimbrial gene, a candidate for the elusive EPEC adherence factor responsible for localized adherence.