title: Bordetella pertussis TonB, a Bvg-independent virulence determinant.
abstract: In gram-negative bacteria, high-affinity iron uptake requires the TonB/ExbB/ExbD envelope complex to release iron chelates from their specific outer membrane receptors into the periplasm. Based on sequence similarities, the Bordetella pertussis tonB exbB exbD locus was identified on a cloned DNA fragment. The tight organization of the three genes suggests that they are cotranscribed. A putative Fur-binding sequence located upstream from tonB was detected in a Fur titration assay, indicating that the tonB exbB exbD operon may be Fur-repressed in high-iron growth conditions. Putative structural genes of the beta-subunit of the histone-like protein HU and of a new two-component regulatory system were identified upstream from tonB and downstream from exbD, respectively. A B. pertussis DeltatonB exbB::Km(r) mutant was constructed by allelic exchange and characterized. The mutant was impaired for growth in low-iron medium in vitro and could not use ferrichrome, desferal, or hemin as iron sources. Levels of production of the major bacterial toxins and adhesins were similar in the TonB(+)/TonB(-) pair. The DeltatonB exbB mutant was still responsive to chemical modulators of virulence; thus, the BvgA/BvgS two-component system is not TonB dependent. Nevertheless, in vivo in the mouse respiratory infection model, the colonization ability of the mutant was reduced compared to the parental strain.
authors.affiliation: INSERM U447, Institut Pasteur de Lille, 59019 Lille Cedex, France.
authors.forename: E
authors.initials: E
authors.lastname: Pradel
authors.forename: N
authors.initials: N
authors.lastname: Guiso
authors.forename: F D
authors.initials: FD
authors.lastname: Menozzi
authors.forename: C
authors.initials: C
authors.lastname: Locht
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000502:physiology*; D001886:Bordetella pertussis / Q000276:immunology* / Q000472:pathogenicity*; D002460:Cell Line; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000276:immunology; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D005291:Ferrichrome / Q000031:analogs & derivatives / Q000378:metabolism; D005656:Fungal Proteins / Q000276:immunology; D015151:Immunoblotting; D007501:Iron / Q000493:pharmacokinetics; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009154:Mutation; D009876:Operon; D010957:Plasmids; D017386:Sequence Homology, Amino Acid; D017262:Siderophores / Q000276:immunology; D013997:Time Factors; D014157:Transcription Factors / Q000276:immunology; D014774:Virulence
chemical_list: C074202:ALCR protein, Aspergillus nidulans; D001426:Bacterial Proteins; C065601:BvgA protein, Bacteria; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C489314:EvgA protein, E coli; C052874:ExbB protein, E coli; D005656:Fungal Proteins; D008565:Membrane Proteins; D017262:Siderophores; D014157:Transcription Factors; C080662:bvgS protein, Bordetella pertussis; C057616:tonB protein, Bacteria; C489181:tonB protein, E coli; C060790:exbD protein, E coli; D005291:Ferrichrome; C015657:albomycin; D007501:Iron