Commensal and pathogenic Escherichia coli use a common pilus adherence factor for epithelial cell colonization

Abstract

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a food-borne pathogen that causes hemorrhagic colitis and the hemolytic uremic syndrome. Colonization of the human gut mucosa and production of potent Shiga toxins are critical virulence traits of EHEC. Although EHEC O157:H7 contains numerous putative pili operons, their role in the colonization of the natural bovine or accidental human hosts remains largely unknown. We have identified in EHEC an adherence factor, herein called E. coli common pilus (ECP), composed of a 21-kDa pilin subunit whose amino acid sequence corresponds to the product of the yagZ (renamed ecpA) gene present in all E. coli genomes sequenced to date. ECP production was demonstrated in 121 (71.6%) of a total of 169 ecpA ؉ strains representing intestinal and extraintestinal pathogenic as well as normal flora E. coli. High-resolution ultrastructural and immunofluorescence studies demonstrated the presence of abundant peritrichous fibrillar structures emanating from the bacterial surface forming physical bridges between bacteria adhering to cultured epithelial cells. Isogenic ecpA mutants of EHEC O157:H7 or fecal commensal E. coli showed significant reduction in adherence to cultured epithelial cells. Our data suggest that ECP production is a common feature of E. coli colonizing the human gut or other host tissues. ECP is a pilus of EHEC O157:H7 with a potential role in host epithelial cell colonization and may represent a mechanism of adherence of both pathogenic and commensal E. coli.pili ͉ enterohemorrhagic Escherichia coli ͉ normal flora

Fimbrial Adhesins Produced by Atypical Enteropathogenic Escherichia coli Strains

“…Curli have also been associated with biofilm development at low temperatures in one aEPEC O55:H7 strain (48). Another example of a fimbrial adhesin, which may represent a mechanism of host cell adherence and colonization of both pathogenic and commensal E. coli strains, is the E. coli common pilus (ECP) (36). This pilus was first documented in association with strains of E. coli responsible for causing meningitis or septicemia (newborn meningitis E. coli [NMEC]) and was originally named MAT (meningitis associated and temperature regulated) (35).…”

“…This pilus was first documented in association with strains of E. coli responsible for causing meningitis or septicemia (newborn meningitis E. coli [NMEC]) and was originally named MAT (meningitis associated and temperature regulated) (35). Knockout ecpA mutants of EHEC, EPEC, and EAEC are less adherent to host cells than ECPproducing strains (4,36,40). Likewise, NMEC strains with deletion of the ecp operon are incapable of producing biofilms (24).…”

“…Likewise, NMEC strains with deletion of the ecp operon are incapable of producing biofilms (24). ECP is composed of a 21-kDa pilin subunit, and antibodies against the pilus have been used as a probe to detect the presence of ECP on diarrheagenic E. coli strains adhering to cultured epithelial cells (5,36,40). Recently, Scaletsky et al (42) showed that the major pilin ecpA gene was present in all of the 29 aEPEC strains belonging to different serotypes tested, but no information is available regarding the actual production of the pili in this group.…”

Escherichia coli Common Pilus (ECP) Targets Arabinosyl Residues in Plant Cell Walls to Mediate Adhesion to Fresh Produce Plants

“…Unusually for classical tip adhesins, EcpD can be polymerized independently, which requires an N-terminal extension in EcpD, or with the major pilin domain (18). Several roles have been described for ECP, including binding to cultured human epithelial cells (16,17,20), colonization of infant mice (21), and biofilm development through interorganelle binding of EcpA (22). The regulator EcpR represses the flagellar master operon flhDC, supporting the role for EcpA in biofilms (23).…”

“…The ecp operon is ubiquitous across E. coli and even conserved for some other enteric species (15)(16)(17)(18)(19). ECP belongs to the chaperoneusher family encoded by the ecpRABCDE operon where EcpA encodes the pilin domain and EcpD encodes the polymerized tip adhesin.…”