Phragmoplast Orienting Kinesin 2 Is a Weak Motor Switching between Processive and Diffusive Modes
Phragmoplast Orienting Kinesin 2 Is a Weak Motor Switching between Processive and Diffusive Modes
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DOI：
10.1016/j.bpj.2018.06.012
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发表时间：
2018-07-17
影响因子：
3.4
通讯作者：
Schaeffer, Erik
中科院分区：
文献类型：
--
作者：
Chugh, Mayank;Reissner, Maja;Schaeffer, Erik
植物的发育和形态依赖于胞质分裂过程中新细胞壁的准确插入。然而，植物细胞如何正确地定向新的细胞壁却知之甚少。两个驱动蛋白12类成员，成膜体定向驱动蛋白1（POK1）和POK2，参与了这一过程，但这些分子机器如何工作尚不清楚。在这里，我们使用在体内和单分子在体外测量，以确定如何拟南芥POK2马达机械功能。我们发现POK2是一个非常弱的，平均加端导向的，中等速度的驱动蛋白。有趣的是，POK2之间切换的进行性和扩散模式，其特征在于一个排他性的状态均方位移分析。我们的研究结果支持一个模型，POK电机推动对周边微管的成膜体的指导。这种推动模型可以从机械上解释分裂部位明显变窄的现象。总之，我们的研究结果为主动马达如何准确定位植物中的新细胞壁提供了机械见解。
Plant development and morphology relies on the accurate insertion of new cell walls during cytokinesis. However, how a plant cell correctly orients a new wall is poorly understood. Two kinesin class-12 members, phragmoplast orienting kinesin 1 (POK1) and POK2, are involved in the process, but how these molecular machines work is not known. Here, we used in vivo and single-molecule in vitro measurements to determine how Arabidopsis thaliana POK2 motors function mechanically. We found that POK2 is a very weak, on average plus-end-directed, moderately fast kinesin. Interestingly, POK2 switches between processive and diffusive modes characterized by an exclusive-state mean-squared-displacement analysis. Our results support a model that POK motors push against peripheral microtubules of the phragmoplast for its guidance. This pushing model may mechanically explain the conspicuous narrowing of the division site. Together, our findings provide mechanical insight into how active motors accurately position new cell walls in plants.