An auxin transport inhibitor targets villin-mediated actin dynamics to regulate polar auxin transport

First author: Minxia Zou; Affiliations: Beijing Normal University (北京师范大学): Beijing, China

Corresponding author: Jiejie Li

Auxin transport inhibitors are essential tools for understanding auxin-dependent plant development. One mode of inhibition affects actin dynamics; however, the underlying mechanisms remain unclear. In this study, we characterized the action of 2,3,5-triiodobenzoic acid (TIBA) on actin dynamics in greater mechanistic detail. By surveying mutants for candidate actin-binding proteins with reduced TIBA sensitivity, we determined that Arabidopsis (Arabidopsis thaliana) villins contribute to TIBA action. By directly interacting with the C-terminal headpiece domain of villins, TIBA causes villin to oligomerize, driving excessive bundling of actin filaments. The resulting changes in actin dynamics impair auxin transport by disrupting the trafficking of PIN auxin efflux carriers and reducing their levels at the plasma membrane (PM). Collectively, our study provides mechanistic insight into the link between the actin cytoskeleton, vesicle trafficking, and auxin transport.

生长素运输抑制剂对于理解依赖生长素的生长发育是一个非常有用的工具。这些抑制剂发挥作用的方式之一就是通过影响肌动蛋白动态，然而潜在的分子机制还不清楚。本文中，作者研究了2,3,5-三碘苯甲酸TIBA作用于肌动蛋白动态的分子机制。作者发现了一个候选肌动蛋白结合蛋白的突变体对于TIBA的敏感性降低，深入研究发现拟南芥的villins基因作用于TIBA功能的发挥。TIBA通过直接与villins碳端的headpiece结构域发生互作，导致villin寡聚化，从而驱动肌动蛋白丝过度集束。肌动蛋白动态的改变通过扰乱生长素转运蛋白PIN的运输，并降低其在质膜上的水平，最终导致了生长素转运缺陷。综上，本文的研究揭示了一个能够将肌动蛋白细胞骨架、囊泡运输以及生长素转运联系起来的分子机制。

通讯：李杰婕 (http://cls.bnu.edu.cn/xuekejianshe/shiziduiwu/xianrenjiaoshi/qrsj/546.html)

个人简介：2002-2006年，中国农业大学，学士；2006-2011年，中国农业大学，博士；2011-2015年，美国普渡大学，博士后。

研究方向：植物发育与免疫应答的细胞信号网络。

doi: https://doi.org/10.1104/pp.19.00064

Journal: Plant Physiology

First Published: July 16, 2019