Dynamic Modulation of Fimbrial Extension and FimH-Mannose Binding Force on Live Bacteria Under pH Changes: A Molecular Atomic Force Microscopy Analysis

作者：Jacquot A; Sakamoto C; Razafitianamaharavo A; Caillet C; Merlin J; Fahs A; Ghigo J M; Beloin C; Duval J F L; Francius G^*

来源：Journal of Biomedical Nanotechnology, 2014, 10(11): 3361-3372.

DOI：10.1166/jbn.2014.1905

• Single Molecule Force Spectroscopy
• Type 1 Fimbriae
• Unwinding
• AFM
• Bacteria

Mechanical and conformational properties of type 1 fimbriae were evaluated on live bacterial cells by Single Molecule Force Spectroscopy (SMFS) and Dynamic Force Spectroscopy (DFS) in buffered solutions whose pH varied from 3 to 9. We evidenced that both fimbrial extension and fimbrial binding force to mannosylated-surface are modulated with changing the externally applied shear force and the solution pH. In particular, intertwined FimA-FimA and FimH-mannose interactions lead to a 5 to 25-fold decrease of the fimbrial unwinding for pulling rates larger than 10 mu m/s and for pH values outside the range 5 to 7. In this pH range, the FimH-mannose binding force is maximal with a magnitude of similar to 150-200 pN and the fimbriae extension reaches 8 mu m. The enhancement of the FimH-mannose binding force at neutral pH, as evidenced from molecular AFM analyses, strongly correlates with an optimum in yeast agglutination detected at pH 5 to 7. The results reported in this work suggest that %26quot;catch bond effect%26quot; was negligible over the range of pulling rates tested, and both FimA-FimA and FimH-mannose interactions under given pH and external shear force conditions modify the ability of the bacteria to efficiently colonize host surfaces.

• 出版日期2014-11