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- Title
Staphylococcus aureus SigB activity promotes a strong fibronectin–bacterium interaction which may sustain host tissue colonization by small-colony variants isolated from cystic fibrosis patients.
- Authors
Mitchell, Gabriel; Lamontagne, Charles-Antoine; Brouillette, Eric; Grondin, Gilles; Talbot, Brian G.; Grandbois, Michel; Malouin, François
- Abstract
Genes encoding cell-surface proteins regulated by SigB are stably expressed in Staphylococcus aureus small-colony variants (SCVs) isolated from cystic fibrosis (CF) patients. Our hypothesis is that CF-isolated SCVs are locked into a colonization state by sustaining the expression of adhesins such as fibronectin-binding proteins (FnBPs) throughout growth. Force spectroscopy was used to study the fibronectin–FnBPs interaction among strains varying for their SigB activity. The fibronectin–FnBPs interaction was described by a strength of 1000 ± 400 pN (pulling rate of 2 μm s−1), an energetic barrier width of 0.6 ± 0.1 Å and an off-rate below 2 × 10−4 s−1. A CF-isolated SCV highly expressed fnbA throughout growth and showed a sustained capacity to bind fibronectin, whereas a prototypic strain showed a reduced frequency of fibronectin-binding during the stationary growth phase when its fnbA gene was down-regulated. Reduced expression of fnbA was observed in sigB mutants, which was associated with an overall decrease adhesion to fibronectin. These results suggest that the fibronectin–FnBPs interaction plays a role in the formation of a mechanically resistant adhesion of S. aureus to host tissues and supports the hypothesis that CF-isolated SCVs are locked into a colonization state as a result of a sustained SigB activity.
- Subjects
STAPHYLOCOCCUS aureus; CYSTIC fibrosis; FIBRONECTINS; DIAGNOSTIC use of spectrum analysis; TISSUES; BACTERIA; PATIENTS
- Publication
Molecular Microbiology, 2008, Vol 70, Issue 6, p1540
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.2008.06511.x