Dynamics of F-actin, myosin subfragment-1 (S1), and their hydration water studied by quasielastic neutron scattering

F-アクチン及びミオシンS1タンパク質の中性子散乱による動力学解析

松尾 龍人; 荒田 敏昭*; 小田 俊郎*; 藤原 悟

Matsuo, Tatsuhito; Arata, Toshiaki*; Oda, Toshiro*; Fujiwara, Satoru

F-アクチン及びミオシンS1タンパク質とその水和水のピコ秒領域のダイナミクスを中性子準弾性散乱によりJ-PARCを用いて解析した。その結果、F-アクチン構成原子はミオシン構成原子よりも高頻度で揺らいでいることが分かった。また、水和水のスペクトル解析から、F-アクチン水和水の運動性がミオシン水和水よりも大きいことが明らかとなった。これらの結果は、F-アクチンとその水和水の協同的作用がF-アクチンの高い運動性を作り出し、ミオシン結合に最適な構造を素早く探索できることを示唆している。

The picosecond dynamics of F-actin, myosin S1, and their hydration water were studied by quasielastic neutron scattering (QENS) at J-PARC. Analysis of the QENS spectra showed that a larger fraction of the atoms of F-actin undergoes the motions with the smaller residence time than S1. It was also found that the mobility of the hydration water of S1, which was evaluated from the translational diffusion coefficient, the residence time, and the rotational correlation time, is lower than that of bulk water, while that of the hydration water of F-actin is close to that of bulk water. These results suggest that the concerted action of rapidly fluctuating F-actin and its hydration water allows F-actin to explore a wide range of the conformational space, which would facilitate the binding of myosin to F-actin.