Actin fliament plasys an impoilant paIl as to the myosin motility mechanism

肌动蛋白丝状结构对肌球蛋白运动机制有重要意义

• 批准号: 14580673
• 负责人: IWANE Atsuko
• 金额: $ 2.62万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14580673/
• 关键词: Myosin; Actin; Cooperativity; Brawnian motion; EM image; Single molecule imaging; 電顕

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.

我们已经表明，肌球蛋白-V的截短突变体（Tanaka et al. '02）和肌球蛋白-VI（Nishikawa et al. '02）具有非常短的颈域，发展出与具有长颈域的天然肌球蛋白V一样大的连续台阶。在这里，我们提出了一个可能的模型（应变传感器模型）来解释这些结果，而不是杠杆臂模型。当头部在弹簧的热弯曲和伸展的驱动下向前移动到目标区域并与肌动蛋白结合时，传感器会被拉动和拉紧，使运动域与肌动蛋白强烈结合，这可能与磷酸盐的释放有关。或肌球蛋白的异构化。当电机域在相反方向上热扩散时，应变传感器不工作，因为应变方向相反，并且头返回到原始位置。同时，电镜图像显示，在ATP存在下，肌球蛋白VI以36 nm的间隔与肌动蛋白丝协同结合（“热点”）。此外，我们还利用单分子成像技术得到了肌球蛋白促进肌动蛋白丝前向结合的结果。运动到邻近“热点”的方向将由肌球蛋白头和肌动蛋白之间界面处的肌球蛋白同种型特异性相互作用决定，该相互作用对布朗运动产生偏差。目的肌丝的构象变化在肌球蛋白的进行性运动中也起重要作用。

项目成果

T.M.Watanabe, H.Tanaka, A.H.Iwane et al.: "Studying Molecular Motors on the Single Molecule Level."Proc.Natl.Acad.Sci.USA. (in press). (2004)

T.M.Watanabe、H.Tanaka、A.H.Iwane 等人：“在单分子水平上研究分子马达”。Proc.Natl.Acad.Sci.USA。

Y.Ishii, A.H.Iwane, H.Yokota et al.: "Studying Molecular Motors on the Single Molecule Level."Single-Molecule Detection in Solution. 9. 273-292 (2002)

Y.Ishii、A.H.Iwane、H.Yokota 等人：“在单分子水平上研究分子马达”。溶液中的单分子检测。

岩根敦子 他: "分子機械の作動原理"共立出版. 8 (2002)

Atsuko Iwane 等：“分子机器的操作原理”Kyoritsu Shuppan 8 (2002)。

M.Y.Ali, K.Honma, A.H.Iwane et al.: "Unconsimined steps of myosin VI appear longest among known molecular motors."Biophys.J.. (in press). (2004)

M.Y.Ali、K.Honma、A.H.Iwane 等人：“肌球蛋白 VI 的无节制步骤在已知的分子马达中显得最长。”Biophys.J.（出版中）。

M.Y.Ali, K.Homma et al.: "Unconstrained steps of myosin VI appear longest among known molecular motors."Biophys.J. (in press). (2004)

M.Y.Ali、K.Homma 等人：“肌球蛋白 VI 的无约束步骤在已知的分子马达中显得最长。”Biophys.J.