| Project/Area Number |
17570127
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | Chiba University |
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Principal Investigator |
ITO Kohji Chiba University, Faculty of science, research associate, 理学部, 助手 (50302526)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Keiichi Chiba University, Faculty of science, professor, 理学部, 教授 (70053361)
KOJIMA Hiroaki The National Institute of Information and Communications Technology, Kansai Advanced Research Center, chief researcher, 関西先端研究センター, 主任研究員 (00359077)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | myosin / Chara / cytoplasmic streaming / actin / motor protein / kinetic / モーター / ストップドフロー装置 / 光ピンセット装置 |
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| Research Abstract |
Chara corallina class XI myosin is by far the fastest molecular motor. To investigate the molecular mechanism of this fast movement, we performed a kinetic analysis of a recombinant motor domain of Chara myosin. We estimated the time spent in the strongly bound state with actin by measuring rate constants of ADP dissociation from actin-motor domain complex and ATP-induced dissociation of the motor domain from actin. The rate constant of ADP dissociation from acto-motor domain was >2,800 s^<-1> and the rate constant of ATP-induced dissociation of the motor domain from actin at physiological ATP concentration was 2,200 s^<-1>. From these data, the time spent in the strongly bound state with actin was estimated to be <0.82 ms. This value is the shortest among known values for various myosins, and yields the duty ratio of <0.3 with the Vmax value of the actin-activated ATPase activity of 390 s 1. The addition of the long neck domain of myosin Va to the Chara motor domain largely increased the velocity of the motility without increasing the ATP hydrolysis cycle rate, consistent with the swinging lever model. In addition, this study reveals some striking kinetic features of Chara myosin that are suited for the fast movement: a dramatic acceleration of ADP release by actin (1,000-fold) and extremely fast ATP binding rate.
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