Open AccessAllosteric regulation by cooperative conformational changes of actin filaments drives mutually exclusive binding with cofilin and myosin
Author(s) -
Kien Xuan Ngo,
Nobuhisa Umeki,
Saku T. Kijima,
Noriyuki Kodera,
Hiroaki Ueno,
Nozomi Furutani-Umezu,
Jun Nakajima,
Tarow Noguchi,
Akira Nagasaki,
Kiyotaka Tokuraku,
Taro Q.P. Uyeda
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep35449
Subject(s) - cofilin , myosin , actin remodeling , actin , allosteric regulation , microbiology and biotechnology , heavy meromyosin , actin binding protein , biophysics , treadmilling , chemistry , biology , biochemistry , actin cytoskeleton , microfilament , cytoskeleton , receptor , cell
Heavy meromyosin (HMM) of myosin II and cofilin each binds to actin filaments cooperatively and forms clusters along the filaments, but it is unknown whether the two cooperative bindings are correlated and what physiological roles they have. Fluorescence microscopy demonstrated that HMM-GFP and cofilin-mCherry each bound cooperatively to different parts of actin filaments when they were added simultaneously in 0.2 μM ATP, indicating that the two cooperative bindings are mutually exclusive. In 0.1 mM ATP, the motor domain of myosin (S1) strongly inhibited the formation of cofilin clusters along actin filaments. Under this condition, most actin protomers were unoccupied by S1 at any given moment, suggesting that transiently bound S1 alters the structure of actin filaments cooperatively and/or persistently to inhibit cofilin binding. Consistently, cosedimentation experiments using copolymers of actin and actin-S1 fusion protein demonstrated that the fusion protein affects the neighboring actin protomers, reducing their affinity for cofilin. In reciprocal experiments, cofilin-actin fusion protein reduced the affinity of neighboring actin protomers for S1. Thus, allosteric regulation by cooperative conformational changes of actin filaments contributes to mutually exclusive cooperative binding of myosin II and cofilin to actin filaments, and presumably to the differential localization of both proteins in cells.