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A one-headed class V myosin molecule develops multiple large (approximately 32-nm) steps successively
Tomonobu M Watanabe1, Hiroto Tanaka, Atsuko Hikikoshi Iwane
1Formation of Soft Nanomachines, Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, and Department of Biophysical Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
Summary
Single-headed myosin-V motors move processively along actin filaments, challenging the traditional two-headed model. This discovery reveals a novel mechanism for myosin-V
Area of Science:
- Cell biology
- Molecular motors
- Biophysics
Background:
- Class V myosin (myosin-V) is a processive motor protein crucial for intracellular cargo transport.
- Myosin-V moves along actin filaments in large, successive steps (approx. 36 nm).
- The two-headed structure of myosin-V has been the basis for explaining its processive movement mechanism.
Purpose of the Study:
- To investigate whether the two-headed structure is essential for myosin-V's successive movement.
- To elucidate the fundamental mechanism of processive movement in myosin motors.
Main Methods:
- Engineered single-headed myosin-V constructs were created.
- Motility assays were performed using optical trapping nanometry.
- The step size and processivity of single-headed myosin-V were measured.
Main Results:
- A single, one-headed myosin-V construct demonstrated processive movement along actin filaments.
- The engineered single-headed myosin-V took multiple successive steps of approximately 32 nm.
- This finding indicates that the two-headed structure is not essential for processive movement.
Conclusions:
- A novel mechanism, independent of the two-headed structure, underlies myosin-V's successive movement.
- Single-headed myosin motors can exhibit processivity, expanding our understanding of molecular motor function.
- This research redefines the current paradigm of myosin-based cargo transport mechanisms.