An Inducible Bundle-Forming Pilus of Enteropathogenic <i>Escherichia coli</i>

TLDR

Enteropathogenic Escherichia coli causes childhood diarrhea and forms adherent colonies on intestinal surfaces and cultured epithelial cells, with its bundle‑forming pili composed of a 19,500‑Da subunit homologous to Vibrio cholerae toxin‑regulated pilin. EPEC expresses bundle‑forming pili on solid media or HEp‑2 cells, forming a fiber network that links bacteria; five serogroups carry a ~92‑kb plasmid essential for BFP expression and adherence, and antiserum against BFP reduces epithelial infection.

Abstract

Enteropathogenic Escherichia coli (EPEC), a cause of childhood diarrhea, grow on the surface of the small intestine and on cultured epithelial cells as colonies of adherent bacteria. When propagated on solid medium containing blood or attached to HEp-2 cells, EPEC express ropelike bundles of filaments, termed bundle-forming pili (BFP), that create a network of fibers that bind together the individual organisms. BFP were found to be expressed by five EPEC serogroups, each harboring a ∼92-kilobase plasmid previously known to be important for virulence in humans. When two of these strains were cured of this plasmid, they neither expressed BFP nor grew as adherent colonies. An antiserum to BFP reduced the capacity of EPEC to infect cultured epithelial cells. BFP are composed of a repeating subunit of 19,500 daltons, the amino-terminal amino acid sequence of this subunit is homologous to that of the toxin-coregulated pilin of Vibrio cholerae .