Coarse-grained modeling and simulation of actin filament behavior based on Brownian dynamics method

Area of Science:

• Cell Biology
• Biophysics
• Computational Biology

Background:

• Actin filaments are crucial cytoskeletal components involved in cell shape, motility, and mechanosensing.
• Dynamic processes like polymerization, depolymerization, and severing govern actin filament structure and function.
• Understanding these dynamics across molecular to macroscopic scales requires robust mathematical modeling.

Purpose of the Study:

• To develop and simulate a mathematical model for actin filament polymerization, depolymerization, and severing.
• To investigate actin filament dynamics using the Brownian dynamics method, considering monomers as particles and solvent as a continuum.
• To analyze the effects of severing on polymerization and depolymerization rates.

Main Methods:

• Utilized Brownian dynamics to model actin filament polymerization, depolymerization, and severing.
• Simulated actin monomer motion using the Langevin equation.
• Defined polymerization by inter-particle distances and depolymerization by a constant dissociation rate; severing was modeled as a uniform rate along the filament.

Main Results:

• The model successfully reproduced the linear relationship between filament elongation and time.
• Simulations demonstrated the filament turnover process driven by polymerization and depolymerization.
• Severing was shown to accelerate both polymerization and depolymerization rates, consistent with experimental findings.

Conclusions:

• The developed Brownian dynamics model provides a valuable tool for understanding actin filament dynamics.
• The model accurately simulates key actin filament behaviors, including elongation, turnover, and the impact of severing.
• This approach offers insights into the complex interplay of forces and molecular events governing cytoskeletal functions.