1995 Fiscal Year Final Research Report Summary
Extensive studies on the dynamic aspects of myofilament sliding in muscle as a micromachine.
| Project/Area Number |
05305007
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
広領域
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| Research Institution | School of Medicine, Teikyo University |
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Principal Investigator |
SUGI Haruo Teikyo Univ.Sch.Med.Professor, 医学部, 教授 (20082076)
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| Co-Investigator(Kenkyū-buntansha) |
SUTOH Kazuo Univ.Tokyo, Fac.Lib.Arts Assoc.Prof., 教養学部, 助教授 (20111453)
SUGA Hiroyuki Okayama Univ., Sch.Med.Professor, 医学部, 教授 (90014117)
SAEKI Yasutake Tsurumi Univ.Sch.Dent.Assoc.Prof., 歯学部, 助教授 (20046113)
ISHIWATA Shinichi Waseda, Univ.Sch.Tech.Professor, 理工学部, 教授 (10130866)
YAMADA Kazuhiro Oita Med.College Professor, 教授 (20053027)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Muscle contraction / Myofilament / Actomyosin / Santan-clothing |
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| Research Abstract |
The results obtained are summarized as follows.
1.Measurement of the unitary distance of actin-myosin sliding in muscle : Yamada, Sugi and others showed that a glycerinated skeletal muscle fiber shortens uniformly along its entire length by 10 nm/half sarcomere, when it is activated by laser flash photolysis of caged ATP releasing ATP molecules whose number was equal to the total number of myosin molecules within the fiber. Analysis of the flash-induced fiber shortening indicated that the internal resistance against shortening was nearly the same as the maximum isometric force, suggesting that the unitary distance of actin-myosin sliding is about 10 nm in the isometric condition.
2.Function of myosin motor domains as studied by techniques of genetic engineering : Sutoh and others succeeded in preparing mutant myosins from a slime mold, Dictyostelium, and found (1) a segment of myosin subfragment 1 (S-1) consisting only of 760 amino acid residues could still generate sliding force with actin filaments, and (2) mutant myosins, in which amino acid residues are lacking in the subfragment 2 (S-2) region, could slide actin filaments past them with velocities slower than those for control myosin, suggesting the involvement of S-2 in muscle contraction.
3.Development of techniques manipulating single molecules : Kinosita and others developed a light microscope system, with which single fluorosphores could be clearly observed as a result of reduced background fluorescence. This system is extremely useful for studying the mechanochemical reaction between single myosin and single ATP molecules. Ando and others, on the other hand, succeeded in combining an atomic force microscope with a fluorescent microscope, also providing the system for studying the single molecule dynamics of actomyosin-ATP system.
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[Publications] Itakura, S., Yamakawa, H., Toyoshima, Y., Ishijima, A., Kojima, T., Harada, Y., Yanagida, T., Wakabayashi, T.& Sutoh, K.: "Force-generating domain of myosin motor" Biochemical and Biophysical Research Communication. 196. 1504-1510 (1993)
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[Publications] Fisher, A.J., Smith, C.A., Thoden, J., Smith, R., Sutoh, K., Holden, H.M.& Rayment, I.: "X-ray structure of the myosin motor domain of Dictyostelium discoideum complexed with Mg・ADP・BeF and Mg・ADP・ALF4." Biochemistry. 34. 8960-8672 (1995)
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