title: N-acetyllactosamine-induced retraction of bundle-forming pili regulates virulence-associated gene expression in enteropathogenic Escherichia coli.
abstract: Enteropathogenic Escherichia coli (EPEC) are a major cause of infant morbidity and mortality due to diarrhoea in developing countries. The pathogenesis of EPEC is dependent on a coordinated multi-step process culminating in the intimate adherence of the organisms to the host's intestinal mucosa. During the initial stages of the EPEC colonization process, the fimbrial adhesin, bundle-forming pili (BFP), plays an integral role. We previously reported that the major BFP structural subunit, bundlin, displays lectin-like properties, which enables BFP to initially tether EPEC to N-acetyllactosamine (LacNAc) glycan receptors on host cell surfaces. We also reported that incubating EPEC with synthetic LacNAc-bearing neoglycoconjugates not only inhibits their adherence to host cells, but also induces BFP retraction and subsequent degradation of the bundlin subunits. Herein, we demonstrate that the periplasmic serine protease, DegP, is required for degrading bundlin during this process. We also show that DegP appears to act as a bundlin chaperone during BFP assembly and that LacNAc-BSA-induced BFP retraction is followed by transcriptional upregulation of the BFP operon and downregulation of the locus of enterocyte effacement operons in EPEC.
authors.affiliation: Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, AB, Canada.
authors.forename: Romney M
authors.initials: RM
authors.lastname: Humphries
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Griener
authors.forename: Stefanie L
authors.initials: SL
authors.lastname: Vogt
authors.forename: George L
authors.initials: GL
authors.lastname: Mulvey
authors.forename: Tracy
authors.initials: T
authors.lastname: Raivio
authors.forename: Michael S
authors.initials: MS
authors.lastname: Donnenberg
authors.forename: Pavel I
authors.initials: PI
authors.lastname: Kitov
authors.forename: Michael
authors.initials: M
authors.lastname: Surette
authors.forename: Glen D
authors.initials: GD
authors.lastname: Armstrong
mesh_terms: D000606:Amino Sugars / Q000494:pharmacology*; D054308:Enteropathogenic Escherichia coli / Q000166:cytology / Q000235:genetics / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007223:Infant; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D009876:Operon; D033903:Periplasmic Proteins / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000606:Amino Sugars; C104901:BfpA protein, E coli; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D033903:Periplasmic Proteins; D036781:Fimbriae Proteins; C000458:N-acetyllactosamine; C061682:DegP protease; D012697:Serine Endopeptidases