Augmin Antagonizes Katanin at Microtubule Crossovers to Control the Dynamic Organization of Plant Cortical Arrays
Augmin Antagonizes Katanin at Microtubule Crossovers to Control the Dynamic Organization of Plant Cortical Arrays
复制标题
DOI：
10.1016/j.cub.2018.03.007
复制
发表时间：
2018-04
期刊：
影响因子：
9.2
通讯作者：
Guangda Wang;Chaofeng Wang;Weiwei Liu;Yinping Ma;Li Dong;Juan Tian;Yanjun Yu;Zhaosheng Kong
中科院分区：
文献类型：
--
作者：
Guangda Wang;Chaofeng Wang;Weiwei Liu;Yinping Ma;Li Dong;Juan Tian;Yanjun Yu;Zhaosheng Kong
植物细胞不具有中心体，中心体是动物细胞中微管的组织中心;植物细胞微管阵列如何建立并维持其动力学仍然知之甚少[1]。γ-微管蛋白复合物和katanin复合物在植物皮层微管的组织中起核心作用[2-6]。之前，我们报道了augmin复合物将γ-微管蛋白复合物募集到预先存在的微管并启动微管成核[7]。此外，我们描述了katanin p60亚基KTN 1和p80亚基KTN 80之间的复杂相互作用如何在微管分支成核位点或交叉处赋予精确的微管切断[8]。在这里，我们观察到Augmin优先定位于微管交叉。活细胞的观察和分析表明，而一小部分的交叉定位Augmin复合物的行为，以触发新生微管成核，大多数功能稳定的微管交叉的架构。最后，遗传分析和计算模型证实，抑制Augmin活性提高微管切割频率，并有利于形成对齐的微管阵列。结合，我们的研究结果揭示了一个意想不到的作用，Augmin和证明，Augmin拮抗katanin介导的微管切断。此外，我们提出了一种新的机制，如何augmin确定植物皮层微管的自组织，防止微管切断交叉除了触发微管成核。
Plant cells do not possess centrosomes, which serve as the microtubule organizing center in animal cells; how plant cell microtubule arrays are established and maintain their dynamics remain poorly understood [1]. The γ-tubulin complex and the katanin complex play central roles in the organization of plant cortical microtubules [2–6]. Previously, we reported that the augmin complex recruits the γ-tubulin complex to preexisting microtubules and initiates microtubule nucleation [7]. Moreover, we described how an intricate interaction between the katanin p60 subunit KTN1 and the p80 subunit KTN80 confers precise microtubule severing at either microtubule branching nucleation sites or crossovers [8]. Here, we observed that augmin preferentially localizes to microtubule crossovers. Live-cell observations and analyses revealed that, whereas a small portion of crossover-localized augmin complexes act to trigger nascent microtubule nucleation, the majority function in stabilizing the architecture of microtubule crossovers. Finally, genetic analyses and computational modeling confirmed that suppression of augmin activity elevates microtubule severing frequency and facilitates the formation of aligned microtubule arrays. Combined, our findings reveal an unexpected role of augmin and demonstrate that augmin antagonizes katanin-mediated microtubule severing. Furthermore, we propose a novel mechanism for how augmin determines self-organization of plant cortical microtubules by preventing microtubule severing at crossovers in addition to triggering microtubule nucleation.