Li Xin, Zhuang Yuhui, Zhao Wanying, Qu Xiaolu, Wang Juan, Chang Ming, Shen Jiangfeng, Chen Naizhi, Huang Shanjin
Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
New Phytol. 2025 Feb;245(3):1158-1179. doi: 10.1111/nph.20295. Epub 2024 Nov 22.
Villins are versatile, multifunctional actin regulatory proteins. They promote actin stabilization and remodeling mainly via their actin bundling and Ca-dependent severing activities, respectively. Arabidopsis subclass II and III villins normally coexist in cells, but the biological significance of their coexistence remains unknown. Here we demonstrate that subclass II villin binds to Ca with high affinity and exhibits strong severing but weak bundling activity compared to subclass III villin. Subclass II villin plays a dominant role in promoting actin remodeling, which requires its Ca-dependent severing activity. Subclass II villin is also strictly required for physiological processes including oriented organ growth and stress tolerance. By comparison, subclass III villin binds to Ca with low affinity and exhibits weak severing but strong bundling activity, and acts as the major player in controlling actin stabilization and organization. Thus, we demonstrate that multifunctional villin isovariants have diverged biochemically to ensure exquisite control of the actin cytoskeleton to meet different cellular needs in plants. This study provides new insights into the role of villins in fine-tuning actin dynamics and plant development.
绒毛蛋白是多功能的肌动蛋白调节蛋白。它们分别主要通过肌动蛋白成束和钙依赖性切断活性来促进肌动蛋白的稳定和重塑。拟南芥II类和III类绒毛蛋白通常在细胞中共存，但其共存的生物学意义尚不清楚。在这里，我们证明II类绒毛蛋白与钙具有高亲和力结合，并且与III类绒毛蛋白相比，表现出强切断活性但弱成束活性。II类绒毛蛋白在促进肌动蛋白重塑中起主导作用，这需要其钙依赖性切断活性。II类绒毛蛋白对于包括定向器官生长和胁迫耐受性在内的生理过程也是严格必需的。相比之下，III类绒毛蛋白与钙的亲和力低，表现出弱切断活性但强成束活性，并在控制肌动蛋白稳定和组织中起主要作用。因此，我们证明多功能绒毛蛋白同工型在生物化学上已经分化，以确保对肌动蛋白细胞骨架进行精确控制，以满足植物中不同的细胞需求。这项研究为绒毛蛋白在微调肌动蛋白动力学和植物发育中的作用提供了新的见解。
