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Updated: Jun 2, 2026
06:08
Biophysical Characterization of Flagellar Motor Functions
Published on: January 18, 2017
The bacterial fimbrial tip acts as a mechanical force sensor.
Pavel Aprikian1, Gianluca Interlandi, Brian A Kidd
1Department of Microbiology, University of Washington, Seattle, Washington, United States of America.
Plos Biology
|May 17, 2011
Summary
Bacterial fimbriae use a catch bond mechanism to strengthen adhesion under force. The Escherichia coli type 1 fimbrial tip complex exhibits flexible exploration and force sensing for dynamic binding conditions.
Area of Science:
- Biophysics
- Microbiology
- Structural Biology
Background:
- Catch bonds, where binding strengthens under force, are increasingly recognized in biological interactions.
- Mechanical forces are prevalent in vivo, influencing molecular interactions.
- Type 1 fimbriae of Escherichia coli mediate bacterial adhesion to host cells.
Purpose of the Study:
- To elucidate the quaternary structure adaptation of the type 1 fimbrial tip complex for binding under dynamic flow conditions.
- To investigate the force-enhanced interaction of FimH with mannose.
- To understand the dual functionality of the fimbrial tip in exploration and force sensing.
Main Methods:
- Single molecule force spectroscopy to study FimH-mannose interactions.
- Molecular dynamics simulations to analyze protein conformations under force.
- Analysis of the multi-protein tip complex structure of type 1 fimbriae.
Main Results:
- The fimbrial tip complex facilitates shear-dependent adhesion via a force-enhanced catch bond mechanism.
- The FimH lectin domain switches to a high-affinity state upon application of tensile force.
- Flexible conformations in the tip complex allow for bacterial exploration and high binding rates.
Conclusions:
- The type 1 fimbrial tip of Escherichia coli is structurally optimized for dual functions: flexible exploration and force sensing.
- This catch bond mechanism and structural adaptation are likely conserved in other bacterial and eukaryotic adhesive complexes functioning in dynamic environments.
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