title: FlaC, a protein of Campylobacter jejuni TGH9011 (ATCC43431) secreted through the flagellar apparatus, binds epithelial cells and influences cell invasion.
abstract: Type III secretion systems identified in bacterial pathogens of animals and plants transpose effectors and toxins directly into the cytosol of host cells or into the extracellular milieu. Proteins of the type III secretion apparatus are conserved among diverse and distantly related bacteria. Many type III apparatus proteins have homologues in the flagellar export apparatus, supporting the notion that type III secretion systems evolved from the flagellar export apparatus. No type III secretion apparatus genes have been found in the complete genomic sequence of Campylobacter jejuni NCTC11168. In this study, we report the characterization of a protein designated FlaC of C. jejuni TGH9011. FlaC is homologous to the N- and C-terminus of the C. jejuni flagellin proteins, FlaA and FlaB, but lacks the central portion of these proteins. flaC null mutants form a morphologically normal flagellum and are highly motile. In wild-type C. jejuni cultures, FlaC is found predominantly in the extracellular milieu as a secreted protein. Null mutants of the flagellar basal rod gene (flgF) and hook gene (flgE) do not secrete FlaC, suggesting that a functional flagellar export apparatus is required for FlaC secretion. During C. jejuni infection in vitro, secreted FlaC and purified recombinant FlaC bind to HEp-2 cells. Invasion of HEp-2 cells by flaC null mutants was reduced to a level of 14% compared with wild type, suggesting that FlaC plays an important role in cell invasion.
authors.affiliation: Department of Medical Genetics and Microbiology, Medical Science Building, 1 King's College Circle, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
authors.forename: Y C
authors.initials: YC
authors.lastname: Song
authors.forename: S
authors.initials: S
authors.lastname: Jin
authors.forename: H
authors.initials: H
authors.lastname: Louie
authors.forename: D
authors.initials: D
authors.lastname: Ng
authors.forename: R
authors.initials: R
authors.lastname: Lau
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: R
authors.initials: R
authors.lastname: Weerasekera
authors.forename: S
authors.initials: S
authors.lastname: Al Rashid
authors.forename: L A
authors.initials: LA
authors.lastname: Ward
authors.forename: S D
authors.initials: SD
authors.lastname: Der
authors.forename: V L
authors.initials: VL
authors.lastname: Chan
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D016123:Campylobacter jejuni / Q000166:cytology / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D002460:Cell Line; D003593:Cytoplasm / Q000382:microbiology; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology*; D005407:Flagella / Q000378:metabolism / Q000502:physiology*; D005408:Flagellin / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005798:Genes, Bacterial; D006801:Humans; D009068:Movement; D016296:Mutagenesis; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C097681:FlgE protein, Bacteria; C117211:flgFG protein, bacteria; D005408:Flagellin; C067138:flaA protein, bacteria; C416532:flaB flagellin