2003 Fiscal Year Final Research Report Summary
Actin fliament plasys an impoilant paIl as to the myosin motility mechanism
| Project/Area Number |
14580673
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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 | Osaka University |
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Principal Investigator |
IWANE Atsuko Osaka University, Graduate School of Frontier Biosciences, Assistant Professor, 生命機能研究科, 助手 (30252638)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Myosin / Actin / Cooperativity / Brawnian motion / EM image / Single molecule imaging |
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| Research Abstract |
We have shown that a truncation mutant of myosin-V (Tanaka et al.'02) and myosin-VI (Nishikawa et al.'02) with very short neck domains develop successive steps as large as native myosin-V with long neck domains. Here, we propose a possible model (strain-sensor model) to explain these results, instead of the lever arm model. When the head moves to the target zone in the forward direction, driven by thermal bending and stretching of the spring and binds to actin, the sensor is pulled and strained to allow the motor domain to bind strongly to the actin, probably coupled to the release of phosphate or the isomerization of myosin. When the motor domain thermally diffuses in the opposite direction, the strain-sensor does not operate because the direction of strain is opposite and the head returns to the original position. Thus, the myosin head favorably moves to the next target in the forward direction.
In the meantime, EM image showed that myosin VI cooperatively binds to an actin filament at 36nm intervals ("hot spot") in the presence of ATP. Furthermore, we also obtained the result of which the myosin facilitates the combination on actin filament forward direction using single molecule imaging. The direction of the movement to the neighboring "hot spot" would be determined by the myosin isotype specific interaction at the interface between myosin head and actin that creates a bias on the Brownian motion. Conformational changes in aim filaments should also play an important role in myosin processive moving.
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