title: Allosteric regulation by cooperative conformational changes of actin filaments drives mutually exclusive binding with cofilin and myosin.
abstract: 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.
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan.|Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan.
authors.forename: Kien Xuan
authors.initials: KX
authors.lastname: Ngo
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan.
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Umeki
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan.|Miyakonojo National College of Technology, Miyakonojo, Miyazaki 885-8567, Japan.
authors.forename: Saku T
authors.initials: ST
authors.lastname: Kijima
authors.affiliation: Department of Physics and Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan.|PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kodera
authors.affiliation: Department of Applied Sciences, Muroran Institute of Technology, Muroran, Hokkaido 050-8585, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ueno
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan.
authors.forename: Nozomi
authors.initials: N
authors.lastname: Furutani-Umezu
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Nakajima
authors.affiliation: Miyakonojo National College of Technology, Miyakonojo, Miyazaki 885-8567, Japan.
authors.forename: Taro Q P
authors.initials: TQ
authors.lastname: Noguchi
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Nagasaki
authors.affiliation: Department of Applied Sciences, Muroran Institute of Technology, Muroran, Hokkaido 050-8585, Japan.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Tokuraku
authors.affiliation: Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8562, Japan.|Department of Physics, Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan.|Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Taro Q P
authors.initials: TQ
authors.lastname: Uyeda
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000378:metabolism*; D051339:Actin Depolymerizing Factors / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D000494:Allosteric Regulation; D006801:Humans; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009218:Myosins / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D051339:Actin Depolymerizing Factors; D011993:Recombinant Fusion Proteins; D000255:Adenosine Triphosphate; D009218:Myosins