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Structural model of weak binding actomyosin in the prepowerstroke state
Boglárka H Várkuti1, Zhenhui Yang1, Andras Malnasi-Csizmadia2
1From the Department of Biochemistry, Institute of Biology and.
The Journal of Biological Chemistry
|November 23, 2014
Summary
This study models actomyosin's weak binding state, revealing how actin binding primes myosin's lever arm. This actin-induced structural change is crucial for muscle contraction's power stroke.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Actomyosin is the molecular motor responsible for muscle contraction.
- Understanding the initial power stroke state is key to elucidating muscle mechanics.
Purpose of the Study:
- To develop the first in silico model of weak binding actomyosin in the initial power stroke state.
- To represent actin binding-induced structural changes in myosin.
Main Methods:
- Docking an actin trimer to prepowerstroke myosin.
- Performing 100-ns unrestrained molecular dynamics simulations.
- Validating the in silico methodology with experimentally determined EM maps.
Main Results:
- Actin binding induces an extra primed myosin state, involving an 18° lever arm prime and switch 2 loop closure.
- Actin N terminus-activation loop interaction specifically drives this extra primed state.
- In silico rigor structures matched experimental electron microscopy data.
Conclusions:
- Actin binding plays a critical role in initiating the myosin power stroke.
- Actin induces an extra primed myosin state, facilitating the lever arm swing for muscle contraction.
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