Higher-Ordered Actin Structures Remodeled by Arabidopsis ACTIN-DEPOLYMERIZING FACTOR5 Are Important for Pollen Germination and Pollen Tube Growth
Higher-Ordered Actin Structures Remodeled by Arabidopsis ACTIN-DEPOLYMERIZING FACTOR5 Are Important for Pollen Germination and Pollen Tube Growth
复制标题
拟南芥肌动蛋白解聚因子5重塑的高阶肌动蛋白结构对于花粉萌发和花粉管生长很重要
DOI：
10.1016/j.molp.2017.06.001
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发表时间：
2017
期刊：
影响因子：
27.5
通讯作者：
Xiang Yun
中科院分区：
文献类型：
--
作者：
Zhu Jingen;Nan Qiong;Qin Tao;Qian Dong;Mao Tonglin;Yuan Shunjie;Wu Xiaorong;Niu Yue;Bai Qifeng;An Lizhe;Xiang Yun
肌动蛋白细胞骨架的动态变化对花粉萌发和花粉管生长至关重要。肌动蛋白解聚因子(ADF)通常通过切断/解聚肌动蛋白细丝来促进肌动蛋白的周转。最近，我们证明了拟南芥亚类III ADF(ADF5和ADF9)是从保守的F-肌动蛋白解聚功能进化而来的。然而，人们对这些新功能化ADF的生理功能、进化意义以及肌动蛋白捆绑机制知之甚少。在这里，我们报道了ADF5功能的丧失通过影响肌动蛋白束的产生和维持，导致花粉萌发延迟，花粉管生长迟缓，并增加了对菌根素B(Latrunculin B，LatB)处理的敏感性。对活细胞肌动蛋白细丝动力学的检测表明，花粉管中的肌动蛋白结合频率显著降低，这与其生化功能一致。进一步的生化和遗传互补分析表明，ADF5的N-末端和C-末端肌动蛋白结合域都是其生理生化功能所必需的。有趣的是，虽然两者都是非典型的肌动蛋白捆绑ADF，但ADF5而不是ADF9在成熟花粉的生理活动中发挥着重要作用。综上所述，我们的结果表明，ADF5已经进化出肌动蛋白束丝的功能，并在花粉萌发和花粉管生长过程中肌动蛋白束的形成、组织和维持中发挥重要作用。
Dynamics of the actin cytoskeleton are essential for pollen germination and pollen tube growth. ACTIN-DEPOLYMERIZING FACTORs (ADFs) typically contribute to actin turnover by severing/depolymerizing actin filaments. Recently, we demonstrated thatArabidopsissubclass III ADFs (ADF5 and ADF9) evolved F-actin-bundling function from conserved F-actin-depolymerizing function. However, little is known about the physiological function, the evolutional significance, and the actin-bundling mechanism of these neofunctionalized ADFs. Here, we report that loss ofADF5function caused delayed pollen germination, retarded pollen tube growth, and increased sensitive to latrunculin B (LatB) treatment by affecting the generation and maintenance of actin bundles. Examination of actin filament dynamics in living cells revealed that the bundling frequency was significantly decreased inadf5pollen tubes, consistent with its biochemical functions. Further biochemical and genetic complementation analyses demonstrated that both the N- and C-terminal actin-binding domains of ADF5 are required for its physiological and biochemical functions. Interestingly, while both are atypical actin-bundling ADFs, ADF5, but not ADF9, plays an important role in mature pollen physiological activities. Taken together, our results suggest that ADF5 has evolved the function of bundling actin filaments and plays an important role in the formation, organization, and maintenance of actin bundles during pollen germination and pollen tube growth.