Structure of dimeric axonemal dynein in cilia suggests an alternative mechanism of force generation
Structure of dimeric axonemal dynein in cilia suggests an alternative mechanism of force generation
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DOI：
10.1002/cm.21180
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发表时间：
2014-07
期刊：
影响因子：
2.9
通讯作者：
H. Ueno;K. Bui;T. Ishikawa;Y. Imai;Takami Yamaguchi;T. Ishikawa
中科院分区：
文献类型：
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作者：
H. Ueno;K. Bui;T. Ishikawa;Y. Imai;Takami Yamaguchi;T. Ishikawa
纤毛外动力蛋白臂的两个不同的头在搏动过程中产生力以移位微管的机制仍然是未知的。在这份报告中，我们使用冷冻电子断层扫描和图像处理来分析小鼠呼吸纤毛中两种动力蛋白头部的构象变化和每种构象的相对丰度。在不存在核苷酸的情况下，大多数动力蛋白二聚体呈载脂蛋白形式，并且两个头部紧密堆积，而在核苷酸存在下，它们解离并独立移动。动力蛋白外臂重链的头部向邻近的B-小管和轴丝的近端有一个对角移位，而内部重链的头部仅向近端纵向移位。在核苷酸的存在下，大量的动力蛋白二聚体具有以近端移位形式重叠或以载脂蛋白形式重叠的两个头部。在纤毛弯曲过程中，轴丝动力蛋白以短步长移动微管，并且两个头停留在同一位置的时间比细胞质动力蛋白长。这表明外臂动力蛋白二聚体的步骤不受手-手运动的支配，但也表明轴丝动力蛋白和细胞质动力蛋白之间的差异。© 2014 Wiley Periodicals，Inc.
The mechanism by which the two different heads of the ciliary outer dynein arm produce force to translocate the microtubule during beating is still unknown. In this report we use cryo‐electron tomography and image processing to analyze the conformational changes and the relative abundance of each conformation of the two dynein heads from mouse respiratory cilia. In the absence of nucleotides the majority of dynein dimers are in the apo form and both heads are tightly packed, whereas they are dissociated and move independently in the presence of nucleotides. The head of the external outer arm dynein heavy chain has a diagonal shift toward both the neighboring B‐tubule and the proximal end of the axoneme, while the head of the internal heavy chain shifts only longitudinally toward the proximal end. In the presence of nucleotides a significant number of the dynein dimers have two heads overlapped in the proximal shifting form or overlapped in the apo form. During ciliary bending axonemal dynein translocates microtubules by moving with short steps and two heads stay at the same position longer than cytoplasmic dynein. This demonstrates that the step of the outer arm dynein dimer is not dominated by the hand‐over‐hand motion, but also indicates the difference between axonemal dynein and cytoplasmic dynein. © 2014 Wiley Periodicals, Inc.