Measuring Force-Induced Dissociation Kinetics of Protein Complexes Using Single-Molecule Atomic Force Microscopy.

Area of Science:

• Biophysics
• Molecular Biology
• Cell Biology

Background:

• Proteins undergo conformational changes and altered interaction kinetics under mechanical force.
• The precise relationship between mechanical force and protein complex lifetime remains unclear.
• Understanding these force-dependent interactions is crucial for cell adhesion and signaling.

Purpose of the Study:

• To provide a tutorial on characterizing force-dependent regulation of protein interactions.
• To detail methods for single-molecule force clamp measurements using atomic force microscopy (AFM).
• To adapt these methods for studying various protein complexes, focusing on E-cadherins.

Main Methods:

• Overview of theoretical models for force-dependent biomolecular kinetics.
• Step-by-step protocols for in vitro single receptor-ligand bond force measurements.
• Methods for quantifying mechanical responses of protein complexes on living cells.

Main Results:

• Demonstration of AFM-based force clamp measurements for characterizing protein interactions.
• Adaptable protocols for sample preparation, force clamp measurements, and data analysis.
• Identification of limitations in current technologies and proposed solutions.

Conclusions:

• The presented AFM-based single-molecule force clamp technique allows characterization of force-dependent protein interactions.
• The methods are applicable to various protein complexes, including E-cadherins, in both in vitro and in vivo settings.
• Addressing technological limitations will further enhance the study of mechanical forces in biological systems.