Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, 518055 Shenzhen, China.
Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, 518055 Shenzhen, China.
Proc Natl Acad Sci U S A. 2021 Feb 9;118(6). doi: 10.1073/pnas.2024592118.
The gaseous phytohormone ethylene mediates numerous aspects of plant growth and development as well as stress responses. The F-box proteins EIN3-binding F-box protein 1 (EBF1) and EBF2 are key components that ubiquitinate and degrade the master transcription factors ethylene insensitive 3 (EIN3) and EIN3-like 1 (EIL1) in the ethylene response pathway. Notably, EBF1 and EBF2 themselves undergo the 26S proteasome-mediated proteolysis induced by ethylene and other stress signals. However, despite their importance, little is known about the mechanisms regulating the degradation of these proteins. Here, we show that a really interesting new gene (RING)-type E3 ligase, salt- and drought-induced ring finger 1 (SDIR1), positively regulates the ethylene response and promotes the accumulation of EIN3. Further analyses indicate that SDIR1 directly interacts with EBF1/EBF2 and targets them for ubiquitination and proteasome-dependent degradation. We show that SDIR1 is required for the fine tuning of the ethylene response to ambient temperature changes by mediating temperature-induced EBF1/EBF2 degradation and EIN3 accumulation. Thus, our work demonstrates that SDIR1 functions as an important modulator of ethylene signaling in response to ambient temperature changes, thereby enabling plant adaptation under fluctuating environmental conditions.
气态植物激素乙烯介导体植物生长和发育以及应激反应的许多方面。F-box 蛋白 EIN3 结合 F-box 蛋白 1（EBF1）和 EBF2 是关键组件，它们泛素化和降解乙烯反应途径中的主转录因子乙烯不敏感 3（EIN3）和 EIN3 样 1（EIL1）。值得注意的是，EBF1 和 EBF2 本身会受到乙烯和其他应激信号诱导的 26S 蛋白酶体介导的蛋白水解。然而，尽管它们很重要，但对于调节这些蛋白质降解的机制知之甚少。在这里，我们表明一种真正有趣的新基因（RING）-型 E3 连接酶，盐和干旱诱导的环指蛋白 1（SDIR1），正向调节乙烯反应并促进 EIN3 的积累。进一步的分析表明，SDIR1 直接与 EBF1/EBF2 相互作用，并将其靶向泛素化和蛋白酶体依赖性降解。我们表明，SDIR1 通过介导温度诱导的 EBF1/EBF2 降解和 EIN3 积累，对环境温度变化的乙烯反应进行精细调节是必需的。因此，我们的工作表明，SDIR1 作为乙烯信号转导对环境温度变化的重要调节剂，从而使植物能够在波动的环境条件下适应。
