Unidirectional Brownian motion observed in an in silico single molecule experiment of an actomyosin motor

Mitsunori Takano, Tomoki P. Terada, Masaki Sasai

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    The actomyosin molecular motor, the motor composed of myosin II and actin filament, is responsible for muscle contraction, converting chemical energy into mechanical work. Although recent single molecule and structural studies have shed new light on the energy-converting mechanism, the physical basis of the molecular-level mechanism remains unclear because of the experimental limitations. To provide a clue to resolve the controversy between the lever-arm mechanism and the Brownian ratchet-like mechanism, we here report an in silico single molecule experiment of an actomyosin motor.When we placed myosin on an actin filament and allowed myosin to move along the filament, we found that myosin exhibits a unidirectional Brownian motion along the filament. This unidirectionality was found to arise from the combination of a nonequilibrium condition realized by coupling to the ATP hydrolysis and a ratchet-like energy landscape inherent in the actin-myosin interaction along the filament, indicating that a Brownian ratchet-like mechanism contributes substantially to the energy conversion of this molecular motor.

    Original languageEnglish
    Pages (from-to)7769-7774
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Issue number17
    Publication statusPublished - 2010 Apr 27



    • Functional funnel
    • Mechano-chemical coupling
    • Molecular dynamics simulation
    • Molecular machines
    • Molecular motors

    ASJC Scopus subject areas

    • General

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