Bordetella pertussis TonB, a Bvg-Independent Virulence Determinant
AUTOR(ES)
Pradel, Elizabeth
FONTE
American Society for Microbiology
RESUMO
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 β-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 ΔtonB exbB::Kmr 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 ΔtonB 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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=97367Documentos Relacionados
- Neisseria meningitidis tonB, exbB, and exbD genes: Ton-dependent utilization of protein-bound iron in Neisseriae.
- TonB Is Required for Intracellular Growth and Virulence of Shigella dysenteriae
- Two TonB Systems in Actinobacillus pleuropneumoniae: Their Roles in Iron Acquisition and Virulence
- Molecular characterization of the Enterobacter aerogenes tonB gene: identification of a novel type of tonB box suppressor mutant.
- TonB-Dependent Systems of Uropathogenic Escherichia coli: Aerobactin and Heme Transport and TonB Are Required for Virulence in the Mouse