State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, P. R. China; College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, P. R. China.
Mol Plant. 2016 Dec 5;9(12):1570-1582. doi: 10.1016/j.molp.2016.11.002. Epub 2016 Nov 14.
Recent discovery of PYR/PYL/RCAR-type abscisic acid (ABA) receptors has become one of most significant advances in plant science in the past decade. In mammals, endosomal sorting acts as an important pathway to downregulate different types of receptors, but its role in plant hormone signaling is poorly understood. Here, we report that an ubiquitin E2-like protein, VPS23A, which is a key component of ESCRT-I, negatively regulates ABA signaling. VPS23A has epistatic relationship with PYR/PYL/RCAR-type ABA receptors and disruption of VPS23A enhanced the activity of key kinase OST1 in the ABA signaling pathway under ABA treatment. Moreover, VPS23A interacts with PYR1/PYLs and K63-linked diubiquitin, and PYL4 possesses K63-linked ubiquitinated modification in vivo. Further analysis revealed that VPS23A affects the subcellular localization of PYR1 and the stability of PYL4. Taken together, our results suggest that VPS23A affects PYR1/PYL4 via vacuole-mediated degradation, providing an advanced understanding of both the turnover of ABA receptors and ESCRTs in plant hormone signaling.
近年来，PYR/PYL/RCAR 型脱落酸（ABA）受体的发现已成为过去十年植物科学领域最重大的进展之一。在哺乳动物中，内体分选作用是下调不同类型受体的重要途径，但它在植物激素信号转导中的作用尚不清楚。在这里，我们报告一个泛素 E2 样蛋白 VPS23A，它是 ESCRT-I 的关键组成部分，负调控 ABA 信号。VPS23A 与 PYR/PYL/RCAR 型 ABA 受体具有上位性关系，破坏 VPS23A 增强了 ABA 处理下 ABA 信号通路中关键激酶 OST1 的活性。此外，VPS23A 与 PYR1/PYLs 和 K63 连接的二泛素相互作用，PYL4 在体内具有 K63 连接的泛素化修饰。进一步的分析表明，VPS23A 影响 PYR1 的亚细胞定位和 PYL4 的稳定性。总之，我们的结果表明，VPS23A 通过液泡介导的降解影响 PYR1/PYL4，为理解 ABA 受体和 ESCRTs 在植物激素信号转导中的周转提供了新的认识。
