Internal dynamics of F-actin studied by neutron scattering

Fujiwara, Satoru; Plazanet, M.*; Matsumoto, Fumiko; Oda, Toshiro*

A variety of functions related to cell motility of F-actin, a filamentous polymer formed by polymerization of the monomers (G-actin), arises from flexibility of F-actin. Understanding the multi-functions of actin thus requires understanding flexibility of F-actin. Understanding flexibility of F-actin requires characterizing hierarchy of dynamics from internal dynamics of the actin-protomer to large-scale motions of F-actin. We performed elastic incoherent and quasielastic neutron scattering (EINS and QENS) experiments, to characterize dynamic properties of F-actin and G-actin. Analysis of the mean square displacements, estimated from the EINS experiments, showed that G-actin is softer than F-actin. Further characterization of the internal motions of the actin-protomers from the QENS spectra showed that these motions have distinct distributions in amplitudes and rates, and the differences in the behavior of F-actin and G-actin arise from the differences in this dynamical heterogeneity.