How selective severing by katanin promotes order in the plant cortical microtubule array
How selective severing by katanin promotes order in the plant cortical microtubule array
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DOI：
10.1073/pnas.1702650114
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发表时间：
2017-07-03
影响因子：
11.1
通讯作者：
Mulder, Bela M.
中科院分区：
文献类型：
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作者：
Deinum, Eva E.;Tindemans, Simon H.;Mulder, Bela M.
植物形态发生需要差异的和通常不对称的生长。皮质微管阵列在控制单个细胞的各向异性扩张中起着关键作用。虽然高度组织化，阵列仍然可以快速变化，以响应内部和外部的线索。实验已经确定微管切断酶katanin是控制阵列组织状态的核心参与者。Katanin行动是需要正常的对齐和适应阵列方向的机械，环境和发展的刺激。然而，我们对katanin如何发挥其控制作用仍知之甚少。一方面，从理论的角度来看，阵列排序依赖于通过微管之间频繁的灾难性碰撞来“淘汰”不协调的微管。切断会降低平均微管长度和寿命，从而削弱排列的驱动力。另一方面，有人建议在微管交叉处选择性切断可以促进去除不一致的微管。在这里，我们表明，这一明显的冲突可以通过系统地剖析所有相关互动的作用来解决。这个程序允许识别的充分和必要的条件，katanin，以促进阵列对齐，强调实验观察到的选择性切断的“交叉”微管在交叉的至关重要性，并揭示了迄今为止没有赞赏的作用微管捆绑。我们将展示如何理解潜在的机制可以帮助解释实验结果和设计未来的实验。
Plant morphogenesis requires differential and often asymmetric growth. A key role in controlling anisotropic expansion of individual cells is played by the cortical microtubule array. Although highly organized, the array can nevertheless rapidly change in response to internal and external cues. Experiments have identified the microtubule-severing enzyme katanin as a central player in controlling the organizational state of the array. Katanin action is required both for normal alignment and the adaptation of array orientation to mechanical, environmental, and developmental stimuli. How katanin fulfills its controlling role, however, remains poorly understood. On the one hand, from a theoretical perspective, array ordering depends on the "weeding out" of discordant microtubules through frequent catastrophe-inducing collisions among microtubules. Severing would reduce average microtubule length and lifetime, and consequently weaken the driving force for alignment. On the other hand, it has been suggested that selective severing at microtubule crossovers could facilitate the removal of discordant microtubules. Here we show that this apparent conflict can be resolved by systematically dissecting the role of all of the relevant interactions in silico. This procedure allows the identification of the sufficient and necessary conditions for katanin to promote array alignment, stresses the critical importance of the experimentally observed selective severing of the "crossing" microtubule at crossovers, and reveals a hitherto not appreciated role for microtubule bundling. We show how understanding the underlying mechanism can aid with interpreting experimental results and designing future experiments.