Thu, 21 Aug 2008 15:17:40 BST CiteULike: cactus Ishii http://www.citeulike.org/user/cactus/author/Ishii CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/cactus/article/2433730 <i>Biosystems, Vol. 88, No. 3. (April 2007), pp. 293-300.</i><br /><br />A recent study with single molecule measurements has reported that muscle myosin, a molecular motor, stochastically generates multiple steps along an actin filament associated with the hydrolysis of a single ATP molecule [Kitamura, K., Tokunaga, M., Esaki, S., Iwane, A.H., Yanagida, T., 2005. Mechanism of muscle contraction based on stochastic properties of single actomyosin motors observed in vitro. Biophysics 1, 1-19]. We have built a model reproducing such a stochastic movement of a myosin molecule incorporated with ATPase reaction cycles and demonstrated that the thermal fluctuation was a key for the function of myosin molecules [Esaki, S., Ishii, Y., Yanagida, T., 2003. Model describing the biased Brownian movement of myosin. Proc. Jpn. Acad. 79 (Ser B), 9-14]. The size of the displacement generated during the hydrolysis of single ATP molecules was limited within a half pitch of an actin filament when a single myosin molecules work separately. However, in muscle the size of the displacement has been reported to be greater than 60 nm [Yanagida, T., Arata, T., Oosawa, F., 1985. Sliding distance of actin filament induced by a myosin crossbridge during one ATP hydrolysis cycle. Nature 316, 366-369; Higuchi et al., 1991]. The difference suggests cooperative action between myosin heads in muscle. Here we extended the model built for an isolated myosin head to a system in which myosin heads are aligned in muscle arrangement to understand the cooperativity between heads. The simulation showed that the rotation of the actin filament [Takezawa, Y., Sugimoto, Y., Wakabayashi, K., 1998. Extensibility of the actin and myosin filaments in various states of skeletal muscles as studied by X-ray diffraction. Adv. Exp. Med. Biol. 453, 309-317; Wakabayashi, K., Ueno, Y., Takezawa, Y., Sugimoto, Y., 2001. Muscle contraction mechanism: use of X-ray synchrotron radiation. Nat. Enc. Life Sci. 1-11] associated with the release of ATPase products and binding of ATP as well as interaction between myosin heads allowed the myosin filament to move greater than a half pitch of the actin filament while a single ATP molecule is hydrolyzed. Our model demonstrated that the movement is loosely coupled to the ATPase cycle as observed in muscle. Cooperative actions between myosin heads bring effective functions Seiji Esaki Yoshiharu Ishii Masatoshi Nishikawa Toshio Yanagida doi:10.1016/j.biosystems.2006.03.013 Biosystems, Vol. 88, No. 3. (April 2007), pp. 293-300. 2008-02-27T06:44:31-00:00 2007 Biosystems 88 3 293 300 model motor myosin http://www.citeulike.org/user/cactus/article/2068085 <i>Nature Structural & Molecular Biology, Vol. 14, No. 12. (02 December 2007), pp. 1157-1164.</i> Evidence of fibril-like β-sheet structures in a neurotoxic amyloid intermediate of Alzheimer's β-amyloid Sandra Chimon Medhat Shaibat Christopher Jones Diana Calero Buzulagu Aizezi Yoshitaka Ishii doi:10.1038/nsmb1345 Nature Structural & Molecular Biology, Vol. 14, No. 12. (02 December 2007), pp. 1157-1164. 2007-12-06T17:53:38-00:00 2007 Nature Structural & Molecular Biology 1545-9993 14 12 1157 1164 Nature Publishing Group amyloid experiment nmr structure