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Updated: Jun 24, 2026
06:53
Probing Myosin Ensemble Mechanics in Actin Filament Bundles Using Optical Tweezers
Published on: May 4, 2022
Actomyosin interaction: mechanical and energetic properties in different nucleotide binding states
Iuliana Aprodu1, Alberto Redaelli1, Monica Soncini1
1Department of Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy.
International Journal of Molecular Sciences
|March 28, 2009
Summary
Myosin
Area of Science:
- Biophysics
- Molecular Biology
- Biochemistry
Background:
- The actomyosin interaction is fundamental to muscle contraction and intracellular transport.
- Understanding the cross-bridge cycle's dynamics and energetics is crucial for elucidating actomyosin mechanics.
Purpose of the Study:
- To quantify the interaction strength between actin monomers and myosin in various nucleotide-bound states (nucleotide-free, ATP, ADP.Pi, and ADP).
- To investigate how nucleotide binding and hydrolysis influence myosin-actin affinity.
Main Methods:
- Construction of molecular models of myosin-actin complexes using cryo-electron microscopy data.
- Employing molecular dynamics simulations with a virtual spring to model myosin unbinding from actin.
- Applying a pulling force to simulate the unbinding process and measure interaction forces.
Main Results:
- Myosin's affinity for actin is significantly modulated by the nucleotide state of its active site.
- The interaction force decreased from 0.83 nN (nucleotide-free) to 0.27 nN (ATP state).
- Following ATP hydrolysis and Pi release, the force increased to 0.60 nN (ADP state).
Conclusions:
- The nucleotide-dependent states of myosin critically regulate its interaction strength with actin.
- These findings provide quantitative insights into the energetic landscape of the actomyosin cross-bridge cycle.
- The study highlights the role of nucleotide binding and hydrolysis in modulating mechanical force generation.
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