Atomic Resolution of Muscle Contraction

A group of researchers led by Specially Appointed Assistant Professor FUJII Takashi and Professor NAMBA Keiichi unraveled the three-dimensional structure of actomyosin rigor complex (complex of actin and myosin filaments), clarifying how skeletal muscles contract at high speed and high efficiency, a world first.

It had been thought that binding of actin filament consisting of skeletal muscles to myosin filament changed muscle structure and generated muscle contraction; however, how myosin filament used adenosine triphosphate (ATP), an energy source, and why skeletal muscles could contract at high speed and high efficiency were not known.

The group took images of actomyosin rigor complex with cryo-electron microscopy and examined its 3D structure by using image analysis methods. This group demonstrated the structural change of myosin head at the time of strong binding of myosin to actin filament and clarified that thermal fluctuations were used as contraction energy.

The group has elucidated the mechanism of quick muscle contraction and its high energy efficiency. It is hoped that this will be applied to the design of energy-saving nanodevices based on this mechanism.

Reference:
Fujii, T., & Namba, K. (2017). Structure of actomyosin rigour complex at 5.2 Å resolution and insights into the ATPase cycle mechanism. Nature Communications, 8, 13969. doi:10.1038/ncomms13969

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