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JChemPhys_133_045103.pdf1.28 MBAdobe PDF見る/開く
タイトル: Entropic potential field formed for a linear-motor protein near a filament: Statistical-mechanical analyses using simple models.
著者: Amano, Ken-Ichi
Yoshidome, Takashi
Iwaki, Mitsuhiro
Suzuki, Makoto
Kinoshita, Masahiro  kyouindb  KAKEN_id
著者名の別形: 木下, 正弘
発行日: 28-Jul-2010
出版者: American Institute of Physics
誌名: The Journal of chemical physics
巻: 133
号: 4
論文番号: 045103
抄録: We report a new progress in elucidating the mechanism of the unidirectional movement of a linear-motor protein (e.g., myosin) along a filament (e.g., F-actin). The basic concept emphasized here is that a potential field is entropically formed for the protein on the filament immersed in solvent due to the effect of the translational displacement of solvent molecules. The entropic potential field is strongly dependent on geometric features of the protein and the filament, their overall shapes as well as details of the polyatomic structures. The features and the corresponding field are judiciously adjusted by the binding of adenosine triphosphate (ATP) to the protein, hydrolysis of ATP into adenosine diphosphate (ADP)+Pi, and release of Pi and ADP. As the first step, we propose the following physical picture: The potential field formed along the filament for the protein without the binding of ATP or ADP+Pi to it is largely different from that for the protein with the binding, and the directed movement is realized by repeated switches from one of the fields to the other. To illustrate the picture, we analyze the spatial distribution of the entropic potential between a large solute and a large body using the three-dimensional integral equation theory. The solute is modeled as a large hard sphere. Two model filaments are considered as the body: model 1 is a set of one-dimensionally connected large hard spheres and model 2 is a double helical structure formed by two sets of connected large hard spheres. The solute and the filament are immersed in small hard spheres forming the solvent. The major findings are as follows. The solute is strongly confined within a narrow space in contact with the filament. Within the space there are locations with sharply deep local potential minima along the filament, and the distance between two adjacent locations is equal to the diameter of the large spheres constituting the filament. The potential minima form a ringlike domain in model 1 while they form a pointlike one in model 2. We then examine the effects of geometric features of the solute on the amplitudes and asymmetry of the entropic potential field acting on the solute along the filament. A large aspherical solute with a cleft near the solute-filament interface, which mimics the myosin motor domain, is considered in the examination. Thus, the two fields in our physical picture described above are qualitatively reproduced. The factors to be taken into account in further studies are also discussed.
著作権等: © 2010 American Institute of Physics
URI: http://hdl.handle.net/2433/128760
DOI(出版社版): 10.1063/1.3462279
PubMed ID: 20687691
出現コレクション:学術雑誌掲載論文等

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