The coordination of cyclic microtubule association/dissociation and tail swing of cytoplasmic dynein
The coordination of cyclic microtubule association/dissociation and tail swing of cytoplasmic dynein
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DOI：
10.1073/pnas.0702370104
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发表时间：
2007-10-09
影响因子：
11.1
通讯作者：
Sutoh, Kazuo
中科院分区：
文献类型：
--
作者：
Imamula, Kenji;Kon, Takahide;Sutoh, Kazuo
动力蛋白运动域由尾部、头部和柄部组成，并且被认为在其ATP酶循环期间通过使尾部摆动抵靠头部而对微管产生力。对于这种“动力冲程”，动力蛋白必须协调尾巴摆动与茎尖处的微管缔合/解离。虽然前一个过程的详细情况正在出现，后一个过程仍有待阐明。通过使用单头重组马达域的Dictycistesteopathy细胞质动力蛋白，我们解决的问题是如何与微管的相互作用的马达域是由ATP酶的步骤调制，如何协调的两个机械循环（微管协会/解离和尾巴摆动），以及ATP酶网站之间的多个网站在马达域调节的协调。基于稳态和预稳态测量，我们证明了在ATP酶循环的大多数中间状态下，两个机械循环同步进行：中风后状态下的运动域与微管强烈结合，K-d约为0.2 μ M，而中风前状态下的大多数运动域与微管弱结合，K-d> 10 μ M。然而，我们的研究结果表明，微管亲和力的变化和尾巴摆动的时间是交错在恢复中风的步骤，其中尾巴摆动从中风后中风前的位置。在AAA 1模块的电机域的ATP酶网站被认为是负责协调这两个机械过程。
The dynein motor domain is composed of a tail, head, and stalk and is thought to generate a force to microtubules by swinging the tail against the head during its ATPase cycle. For this "power stroke," dynein has to coordinate the tail swing with microtubule association/dissociation at the tip of the stalk. Although a detailed picture of the former process is emerging, the latter process remains to be elucidated. By using the single-headed recombinant motor domain of Dictycistelium cytoplasmic dynein, we address the questions of how the interaction of the motor domain with a microtubule is modulated by ATPase steps, how the two mechanical cycles (the microtubule association/dissociation and tail swing) are coordinated, and which ATPase site among the multiple sites in the motor domain regulates the coordination. Based on steady-state and pre-steady-state measurements, we demonstrate that the two mechanical cycles proceed synchronously at most of the intermediate states in the ATPase cycle: the motor domain in the poststroke state binds strongly to the microtubule with a K-d of approximate to 0.2 mu M, whereas most of the motor domains in the prestroke state bind weakly to the microtubule with a K-d of > 10 mu M. However, our results suggest that the timings of the microtubule affinity change and tail swing are staggered at the recovery stroke step in which the tail swings from the poststroke to the prestroke position. The ATPase site in the AAA1 module of the motor domain was found to be responsible for the coordination of these two mechanical processes.