Building complexity: An in vitro study of cytoplasmic dynein with in vivo implications
Building complexity: An in vitro study of cytoplasmic dynein with in vivo implications
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DOI：
10.1016/j.cub.2005.10.039
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发表时间：
2005-12-06
期刊：
影响因子：
9.2
通讯作者：
Gross, SP
中科院分区：
文献类型：
--
作者：
Mallik, R;Petrov, D;Gross, SP
背景：细胞质动力蛋白是负责大多数基于微管的囊泡逆行运输的分子马达。体外单分子实验表明，动力蛋白的功能不如驱动蛋白-1或肌球蛋白-V的功能强大，因为动力蛋白在分离前仅移动有限的距离（约800 nm），并且可以施加适度（约1 pN）的力。然而，动力蛋白驱动的货物在体内移动超过许多微米，并施加多个pN的力。为了确定如何从有限的单分子功能到强大的体内运输，我们开始建立复杂的控制方式，通过使用在体外experiments.Results：我们表明，一个单一的细胞质动力蛋白电机经常转变成一个关闭路径非生产性状态，损害净运输。添加第二（和/或第三）动力蛋白马达，使得货物由两个（或三个）马达而不是一个马达移动，足以恢复体内运动的几个性质;这些性质包括长的货物行程、稳健的运动和增加的力。这种改善的一部分似乎产生于选择性抑制的非生产性状态的动力蛋白，而不是从根本上改变动力蛋白的mechanochemcal cycle.Conclusions：多个动力蛋白一起工作抑制一个单一的电机的缺点，并在体外条件下产生强大的运动。似乎不需要额外的辅因子（例如，Dynactin）用于该改进。由于货物往往是由多个动力蛋白在体内驱动，我们的研究结果表明，改变动力蛋白马达的数量可以允许调制动力蛋白功能从平庸的单一动力蛋白的限制，在体内强大的动力蛋白驱动的运动。
Background: Cytoplasmic dynein is the molecular motor responsible for most retrograde microtubule-based vesicular transport. In vitro single-molecule experiments suggest that dynein function is not as robust as that of kinesin-1 or myosin-V because dynein moves only a limited distance (approximately 800 nm) before detaching and can exert a modest (approximately 1 pN) force. However, dynein-driven cargos in vivo move robustly over many microns and exert forces of multiple pN. To determine how to go from limited single-molecule function to robust in vivo transport, we began to build complexity in a controlled manner by using in vitro experiments.Results: We show that a single cytoplasmic dynein motor frequently transitions into an off-pathway unproductive state that impairs net transport. Addition of a second (and/or third) dynein motor, so that cargos are moved by two (or three) motors rather than one, is sufficient to recover several properties of in vivo motion; such properties include long cargo travels, robust motion, and increased forces. Part of this improvement appears to arise from selective suppression of the unproductive state of dynein rather than from a fundamental change in dynein's mechanochemcal cycle.Conclusions: Multiple dyneins working together suppress shortcomings of a single motor and generate robust motion under in vitro conditions. There appears to be no need for additional cofactors (e.g., dynactin) for this improvement. Because cargos are often driven by multiple dyneins in vivo, our results show that changing the number of dynein motors could allow modulation of dynein function from the mediocre single-dynein limit to robust in vivo-like dynein-driven motion.