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Insights into Actin-Myosin Interactions within Muscle from 3D Electron Microscopy
Kenneth A Taylor1, Hamidreza Rahmani2, Robert J Edwards3
1Florida State University, Institute of Molecular Biophysics, Tallahassee, FL 32306-4380, USA. taylor@biol.fsu.edu.
International Journal of Molecular Sciences
|April 10, 2019
Summary
Understanding actin-myosin interactions in muscle filaments is challenging. This review details electron microscopy studies of Lethocerus flight muscle, revealing myosin head conformational changes during muscle contraction.
Area of Science:
- Muscle physiology
- Biochemistry
- Structural biology
Background:
- Actin-myosin interactions are crucial for muscle contraction.
- In vivo muscle studies are complex due to averaging signals from multiple states.
- Previous research relied heavily on in vitro assays and cryo-electron microscopy (cryoEM) of isolated F-actin.
Purpose of the Study:
- To review the history and progress of visualizing actin-myosin interactions within the muscle filament lattice.
- To understand the conformational changes of myosin heads during muscle contraction in situ.
- To correlate structural changes with biochemical and mechanical states.
Main Methods:
- Electron microscopy (EM) of Lethocerus flight muscle.
- 3D imaging of actin and myosin within the filament lattice.
- Analysis of static and actively contracting muscle states.
Main Results:
- Lethocerus flight muscle provides a unique model due to its favorable filament arrangement.
- Electron microscopy enabled visualization of all myosin cross-bridges contacting actin filaments in thin sections.
- Consistent patterns of myosin head structural changes were observed, correlating with X-ray crystallography data.
Conclusions:
- Visualizing actin-myosin interactions in situ using Lethocerus flight muscle has provided significant insights.
- Electron microscopy has revealed dynamic conformational changes in myosin heads during muscle contraction.
- These findings help explain actomyosin interactions observed in vivo.
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