The kinesin-1 motor protein is regulated by a direct interaction of its head and tail
The kinesin-1 motor protein is regulated by a direct interaction of its head and tail
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DOI：
10.1073/pnas.0803575105
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发表时间：
2008-07-01
影响因子：
11.1
通讯作者：
Rice, Sarah E.
中科院分区：
文献类型：
--
作者：
Dietrich, Kristen A.;Sindelar, Charles V.;Rice, Sarah E.
驱动蛋白-1是一种分子马达蛋白，其沿着沿着运输货物。在细胞内，绝大多数驱动蛋白-1被调节以保存ATP并确保其适当的细胞内分布和与其他分子马达的协调。受调控的驱动蛋白-1在其卷曲螺旋柄的铰链处对折。在IN末端的酶活性头部附近的卷曲螺旋区域和在C末端的调节尾部之间的相互作用使这些球状元件接近并稳定折叠构象。然而，它仍然是一个谜，如何驱动蛋白-l的微管刺激ATP酶活性的调节，在这种折叠的构象。在这里，我们提出的驱动蛋白-1的头部和尾部之间的直接相互作用的证据。我们光化学交联的头部和尾部，并产生了一个8埃的cryoEM的微管上的交联的头-尾复合物重建。这些数据表明，在驱动蛋白-1尾部的保守的基本调控元件直接和特异性地与头部的酶促关键开关I区域相互作用。这种相互作用表明了尾介导的调节驱动蛋白-1的ATP酶活性的机制。在我们的结构中，尾部同时与驱动蛋白-1头部和微管接触，这表明尾部可以调节溶液中的驱动蛋白-1，并将其保持在具有高ADP亲和力的微管暂停状态。驱动蛋白-1头部的开关I区域与尾部的相互作用与小GTP酶与其调节器的相互作用惊人地相似，表明其他驱动蛋白马达可能具有类似的调节机制。
Kinesin-1 is a molecular motor protein that transports cargo along microtubules. Inside cells, the vast majority of kinesin-1 is regulated to conserve ATP and to ensure its proper intracellular distribution and coordination with other molecular motors. Regulated kinesin-1 folds in half at a hinge in its coiled-coil stalk. Interactions between coiled-coil regions near the enzymatically active heads at the IN terminus and the regulatory tails at the C terminus bring these globular elements in proximity and stabilize the folded conformation. However, it has remained a mystery how kinesin-l's microtubule-stimulated ATPase activity is regulated in this folded conformation. Here, we present evidence for a direct interaction between the kinesin-1 head and tail. We photochemically cross-linked heads and tails and produced an 8-angstrom cryoEM reconstruction of the cross-linked head-tail complex on microtubules. These data demonstrate that a conserved essential regulatory element in the kinesin-1 tail interacts directly and specifically with the enzymatically critical Switch I region of the head. This interaction suggests a mechanism for tail-mediated regulation of the ATPase activity of kinesin-1. In our structure, the tail makes simultaneous contacts with the kinesin-1 head and the microtubule, suggesting the tail may both regulate kinesin-1 in solution and hold it in a paused state with high ADP affinity on microtubules. The interaction of the Switch I region of the kinesin-1 head with the tail is strikingly similar to the interactions of small GTPases with their regulators, indicating that other kinesin motors may share similar regulatory mechanisms.