A novel plant actin-microtubule bridging complex regulates cytoskeletal and ER structure at ER-PM contact sites
A novel plant actin-microtubule bridging complex regulates cytoskeletal and ER structure at ER-PM contact sites
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一种新型植物肌动蛋白-微管桥接复合物调节 ER-PM 接触位点的细胞骨架和 ER 结构
DOI：
10.1016/j.cub.2020.12.009
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发表时间：
2021-03-22
期刊：
影响因子：
9.2
通讯作者：
Wang, Pengwei
中科院分区：
文献类型：
--
作者：
Zang, Jingze;Klemm, Sandra;Wang, Pengwei
在植物中，皮质内质网(ER)网络通过ER-PM接触位点(EPCS)连接到质膜(PM)，其结构由EPCS驻留蛋白和细胞骨架维持1？7在植物中观察到EPCS与细胞骨架之间强烈的协同排列，1，8但对EPCS中细胞骨架如何维持和调节知之甚少。在这里，我们使用酵母双杂交筛选和随后的植物体内相互作用研究，通过荧光共振能量转移(FRET)-荧光寿命成像(FLIM)分析来鉴定两个微管结合蛋白，KLCR1(运动蛋白轻链相关蛋白1)和IQD2(IQ67-结构域2)，它们与肌动蛋白结合蛋白NET3C相互作用，形成植物EPCS的一个组成部分，介导肌动蛋白和微管网络之间的联系。NET3C-KLCR1-IQD2模块作为肌动蛋白-微管桥联复合体，直接影响内质网形态和EPCS结构。它们的功能缺失突变体net3a/NET3CRNAi、kLCR1或iqd2显示出路面细胞形态上的缺陷，我们认为这与肌动蛋白细丝和微管的解体有关。总之，我们的结果揭示了一种新的细胞骨架相关复合体，它对于EPCS中细胞骨架结构和内质网形态的维持和组织以及正常的植物细胞形态发生是必不可少的。
In plants, the cortical endoplasmic reticulum (ER) network is connected to the plasma membrane (PM) through the ER-PM contact sites (EPCSs), whose structures are maintained by EPCS resident proteins and the cytoskeleton.1?7 Strong co-alignment between EPCSs and the cytoskeleton is observed in plants,1,8 but little is known of how the cytoskeleton is maintained and regulated at the EPCS. Here, we have used a yeast-two-hybrid screen and subsequent in vivo interaction studies in plants by fluorescence resonance energy transfer (FRET)-fluorescence lifetime imaging microscopy (FLIM) analysis to identify two microtubule binding proteins, KLCR1 (kinesin-light-chain-related protein 1) and IQD2 (IQ67-domain 2), that interact with the actin binding protein NET3C and form a component of plant EPCS that mediates the link between the actin and microtubule networks. The NET3C-KLCR1-IQD2 module, acting as an actin-microtubule bridging complex, has a direct influence on ER morphology and EPCS structure. Their loss-of-function mutants, net3a/NET3C RNAi, klcr1, or iqd2, exhibit defects in pavement cell morphology, which we suggest is linked to the disorganization of both actin filaments and microtubules. In conclusion, our results reveal a novel cytoskeletal-associated complex, which is essential for the maintenance and organization of cytoskeletal structure and ER morphology at the EPCS and for normal plant cell morphogenesis.yyy