title: Synergistic role of curli and cellulose in cell adherence and biofilm formation of attaching and effacing Escherichia coli and identification of Fis as a negative regulator of curli.
abstract: Curli are adhesive fimbriae of Escherichia coli and Salmonella enterica. Expression of curli (csgA) and cellulose (bcsA) is co-activated by the transcriptional activator CsgD. In this study, we investigated the contribution of curli and cellulose to the adhesive properties of enterohaemorragic (EHEC) O157:H7 and enteropathogenic E. coli (EPEC) O127:H6. While single mutations in csgA, csgD or bcsA in EPEC and EHEC had no dramatic effect on cell adherence, double csgAbcsA mutants were significantly less adherent than the single mutants or wild-type strains to human colonic HT-29 epithelial cells or to cow colon tissue in vitro. Overexpression of csgD (carried on plasmid pCP994) in a csgD mutant, but not in the single csgA or bscA mutants, led to significant increase in adherence and biofilm formation in EPEC and EHEC, suggesting that synchronized over-production of curli and cellulose enhances bacterial adherence. In line with this finding, csgD transcription was activated significantly in the presence of cultured epithelial cells as compared with growth in tissue culture medium. Analysis of the influence of virulence and global regulators in the production of curli in EPEC identified Fis (factor for inversion stimulation) as a, heretofore unrecognized, negative transcriptional regulator of csgA expression. An EPEC E2348/69Deltafis produced abundant amounts of curli whereas a double fis/csgD mutant yielded no detectable curli production. Our data suggest that curli and cellulose act in concert to favour host colonization, biofilm formation and survival in different environments.
authors.affiliation: Department of Immunobiology, University of Arizona, 1501 N. Tucson, AZ 85724, USA.
authors.forename: Zeus
authors.initials: Z
authors.lastname: Saldaña
authors.forename: Juan
authors.initials: J
authors.lastname: Xicohtencatl-Cortes
authors.forename: Fabiola
authors.initials: F
authors.lastname: Avelino
authors.forename: Alan D
authors.initials: AD
authors.lastname: Phillips
authors.forename: James B
authors.initials: JB
authors.lastname: Kaper
authors.forename: José L
authors.initials: JL
authors.lastname: Puente
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Girón
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D002417:Cattle; D002460:Cell Line; D002482:Cellulose / Q000235:genetics / Q000378:metabolism*; D054308:Enteropathogenic Escherichia coli / Q000235:genetics / Q000502:physiology*; D004847:Epithelial Cells / Q000382:microbiology; D019453:Escherichia coli O157 / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D035021:Factor For Inversion Stimulation Protein / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D012097:Repressor Proteins / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics
chemical_list: C499694:CsgD protein, E coli; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; C501034:Fis protein, E coli; D012097:Repressor Proteins; D015534:Trans-Activators; C489688:csgA protein, E coli; D002482:Cellulose