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Probing Myosin Ensemble Mechanics in Actin Filament Bundles Using Optical Tweezers
Published on: May 4, 2022
Single-molecule stepping and structural dynamics of myosin X
Yujie Sun1, Osamu Sato, Felix Ruhnow
1Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Nature Structural & Molecular Biology
|April 6, 2010
Summary
Myosin X moves processively along actin filaments in a helical path. Its movement is slower on bundles, suggesting it steps between filaments, enabling diverse cellular functions.
Area of Science:
- Molecular biology
- Cell biology
- Biophysics
Background:
- Myosin X is an unconventional myosin with poorly understood motility.
- Its function in cells involves interactions with actin structures.
Purpose of the Study:
- To investigate the motility properties of dimerized myosin X at the single-molecule level.
- To elucidate the mechanism of myosin X movement along actin filaments and bundles.
Main Methods:
- Single-molecule fluorescence techniques: polTIRF, FIONA, and Parallax.
- Measurement of rotation angles and 3D position of myosin X during movement.
Main Results:
- Myosin X exhibits processive, hand-over-hand stepping in a left-handed helical path.
- Step size and velocity are reduced on actin bundles compared to single filaments.
- Structural flexibility in the neck-tail region and a proposed alpha-helical lever arm extension were identified.
Conclusions:
- Myosin X's unique motility mechanism facilitates its function on diverse actin structures.
- Reduced stepping on bundles suggests filament-to-filament transfer.
- Structural features support myosin X's role in cellular processes requiring interaction with actin.
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