Measurements of motions of actin by neutron spin-echo spectroscopy

Fujiwara, Satoru; Matsumoto, Fumiko; Nakagawa, Hiroshi   ; Endo, Hitoshi*; Oda, Toshiro*

A variety of functions of F-actin related to cell motility arises from flexibility of F-actin that makes interactions with various actin-binding proteins possible. To understand flexibility of F-actin and thereby its multiple functions, it is important to understand dynamic properties of F-actin. As one of the ongoing projects towards this ultimate purpose, we employed neutron spin-echo (NSE) spectroscopy to investigate the motions of F-actin on pico-to-nanosecond timescales and nm spatial scales. We carried out the NSE experiments of F-actin and G-actin with the instrument, iNSE, run by the Institute for Solid State Physics, the University of Tokyo. It was shown that the motions of F-actin and G-actin on nano-scales were described by single relaxation processes, and the motions of F-actin were slower than those of G-actin. Diffusion constants obtained suggested the effects of internal motions of the actin-protomers.