Transport by Populations of Fast and Slow Kinesins Uncovers Novel Family-Dependent Motor Characteristics Important for In Vivo Function
Transport by Populations of Fast and Slow Kinesins Uncovers Novel Family-Dependent Motor Characteristics Important for In Vivo Function
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DOI：
10.1016/j.bpj.2014.09.009
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发表时间：
2014-10-21
影响因子：
3.4
通讯作者：
Tuezel, Erkan
中科院分区：
文献类型：
--
作者：
Arpag, Goeker;Shastry, Shankar;Tuezel, Erkan
细胞内的货物运输通常涉及多种运动类型，或者具有相反的方向性，或者具有相同的方向性但不同的速度。尽管在单分子水平上表征运动蛋白马达方面已经取得了重大进展，但预测它们的整体行为是具有挑战性的，并且需要实验和建模之间的紧密耦合来揭示潜在的马达行为。为了了解附着在同一货物上的不同动力蛋白如何协调它们的运动，我们使用来自动力蛋白-1、-2、-3、-5和-7家族的马达两两混合进行了微管滑翔实验，这些马达经过设计，具有相同的运行长度和表面附着。采用均匀的电机密度，并测量了不同比例的快、慢电机的微管滑动速度。一个粗粒度的计算模型的滑行分析被开发和发现，以概括实验。模拟结合了已公布的力相关速度和运行长度，以及与同一微管结合的马达之间的机械相互作用。仿真结果表明，在多电机实验中，分离力依赖是决定滑行速度的关键参数，而电机顺应性、表面密度和失速力对滑行速度的影响最小。模拟还提供了力依赖解离率的估计，表明kinesin-1和有丝分裂马达kinesin-5和-7在负载下保持微管结合，而kinesin-2和-3很容易分离。这项工作揭示了多运动系统中意想不到的运动行为，并阐明了在细胞中执行不同机械任务的运动蛋白之间的功能差异。
Intracellular cargo transport frequently involves multiple motor types, either having opposite directionality or having the same directionality but different speeds. Although significant progress has been made in characterizing kinesin motors at the single-molecule level, predicting their ensemble behavior is challenging and requires tight coupling between experiments and modeling to uncover the underlying motor behavior. To understand how diverse kinesins attached to the same cargo coordinate their movement, we carried out microtubule gliding assays using pairwise mixtures of motors from the kinesin-1, -2, -3, -5, and -7 families engineered to have identical run lengths and surface attachments. Uniform motor densities were used and microtubule gliding speeds were measured for varying proportions of fast and slow motors. A coarse-grained computational model of gliding assays was developed and found to recapitulate the experiments. Simulations incorporated published force-dependent velocities and run lengths, along with mechanical interactions between motors bound to the same microtubule. The simulations show that the force-dependence of detachment is the key parameter that determines gliding speed in multimotor assays, while motor compliance, surface density, and stall force all play minimal roles. Simulations also provide estimates for force-dependent dissociation rates, suggesting that kinesin-1 and the mitotic motors kinesin-5 and -7 maintain microtubule association against loads, whereas kinesin-2 and -3 readily detach. This work uncovers unexpected motor behavior in multimotor ensembles and clarifies functional differences between kinesins that carry out distinct mechanical tasks in cells.