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Mechanical coordination in motor ensembles revealed using engineered artificial myosin filaments
R F Hariadi1, R F Sommese1, A S Adhikari2
1Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Nature Nanotechnology
|July 8, 2015
Summary
Researchers engineered artificial myosin filaments using DNA nanotubes to study muscle motor coordination. They found motor density and spacing didn't affect actin filament gliding speed, suggesting myosin acts as an energy reservoir for smooth muscle motion.
Area of Science:
- Muscle physiology
- Biophysics
- Molecular motors
Background:
- Muscle force generation relies on coordinated actin-myosin interactions within sarcomeres.
- Understanding ensemble coordination of myosin motors remains a challenge in muscle research.
Purpose of the Study:
- To investigate how myosin motor number, type, and spacing influence actin filament gliding speed.
- To explore the role of myosin ensembles as energy reservoirs in muscle motility.
- To develop a reconstituted system for studying muscle function.
Main Methods:
- Engineered artificial myosin filaments using DNA nanotube scaffolds for precise motor control.
- Utilized dimeric myosin V- and myosin VI-labeled nanotubes to drive actin filament gliding.
- Measured gliding speed in relation to myosin density, spacing, and cross-bridge compliance.
Main Results:
- Neither myosin density nor spacing significantly affected actin filament gliding speed.
- Gliding speed was found to increase with cross-bridge compliance.
- Brownian effects were identified as a limiting factor for gliding speed.
- Demonstrated human β-cardiac myosin-driven actin filament gliding on DNA nanotubes.
Conclusions:
- Myosin ensembles may function as energy reservoirs, buffering stochastic events for smooth muscle contraction.
- Cross-bridge compliance is a key factor in muscle motility, alongside Brownian motion limitations.
- DNA nanotube scaffolds offer a versatile platform for reconstituting and studying muscle motility mechanisms.
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