Mapping Mechanical Force Propagation through Biomolecular Complexes.

Area of Science:

• Biophysics
• Protein Mechanics
• Molecular Interactions

Background:

• Cellulosomes are large protein complexes essential for cellulose degradation.
• Understanding their mechanical stability is key to optimizing enzymatic activity.
• Force propagation within these complexes influences their overall function and resilience.

Purpose of the Study:

• To elucidate the force propagation pathways within a mechanically ultrastable multidomain cellulosome.
• To identify specific structural routes responsible for transmitting mechanical force.
• To correlate these pathways with the complex's high dissociation forces.

Main Methods:

• Employed single-molecule force spectroscopy using an atomic force microscope (AFM).
• Utilized steered molecular dynamics (SMD) simulations.
• Applied a novel network-based correlation analysis combined with AFM directional pulling experiments.

Main Results:

• Visualized distinct force propagation pathways through the cellulosome complex.
• Identified specific stiff paths, including routes nonparallel to the pulling axis.
• Demonstrated a correlation between these pathways and high mechanical dissociation forces.

Conclusions:

• Specific non-linear force transmission routes are critical for the mechanical stability of cellulosomes.
• The identified pathways contribute to the high dissociation forces observed in these protein complexes.
• This study provides a new method for analyzing force propagation in complex protein structures.