Arabidopsis EIN3-binding F-box 1 and 2 form ubiquitin-protein ligases that repress ethylene action and promote growth by directing EIN3 degradation
Arabidopsis EIN3-binding F-box 1 and 2 form ubiquitin-protein ligases that repress ethylene action and promote growth by directing EIN3 degradation
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DOI：
10.1073/pnas.0401698101
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发表时间：
2004-04-27
影响因子：
11.1
通讯作者：
Vierstra, RD
中科院分区：
文献类型：
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作者：
Gagne, JM;Smalle, J;Vierstra, RD
泛素蛋白连接酶（或E3s）对各种细胞内蛋白的泛素化作用在真核细胞调节中起重要作用，主要是通过其选择性靶向蛋白被26S蛋白酶体降解的能力。Skp1, Cullin, F-box （SCF）复合物是一种有影响力的E3类，它使用F-box蛋白将靶标传递到由Skp1， Cullin和Rbx1亚基提供的核心连接酶活性。在拟南芥中可以发现近700个F-box蛋白，这表明SCF E3s可能在植物生理和发育中发挥普遍作用。在这里，我们描述了两个F-box蛋白EBF1和-2的反向遗传分析，它们在SCF复合物中协同抑制乙烯作用。任何一个基因的突变都会引起对外源乙烯及其前体1-氨基环丙烷-l-羧酸的超敏反应。EBF1和-2直接与乙烯不敏感3 （EIN3）相互作用，EIN3是乙烯信号传导的重要转录调节因子。在影响EBF1或-2的突变体中，EIN3水平升高，表明相应的SCF复合物在EIN3分解中协同作用。令人惊讶的是，即使在没有外源乙烯的情况下，双ebf1 ebf2突变体也表现出幼苗生长的实质性停滞和EIN3水平的升高。总之，我们的研究结果表明，依赖于SCFEBF1/ ebf2的泛素化和随后的EIN3的去除不仅对乙烯信号传导至关重要，而且对植物的生长也至关重要。
Ubiquitination of various intracellular proteins by ubiquitin-protein ligases (or E3s) plays an essential role in eukaryotic cell regulation primarily through its ability to selectively target proteins for degradation by the 26S proteasome. Skp1, Cullin, F-box (SCF) complexes are one influential E3 class that use F-box proteins to deliver targets to a core ligase activity provided by the Skp1, Cullin, and Rbx1 subunits. Almost 700 F-box proteins can be found in Arabidopsis, indicating that SCF E3s likely play a pervasive role in plant physiology and development. Here, we describe the reverse genetic analysis of two F-box proteins, EBF1 and -2, that work coordinately in SCF complexes to repress ethylene action. Mutations in either gene cause hypersensitivity to exogenous ethylene and its precursor 1-aminocyclopropane-l-carboxylic acid. EBF1 and -2 interact directly with ethylene insensitive 3 (EIN3), a transcriptional regulator important for ethylene signaling. Levels of EIN3 are increased in mutants affecting either EBF1 or -2, suggesting that the corresponding SCF complexes work together in EIN3 breakdown. Surprisingly, double ebf1 ebf2 mutants display a substantial arrest of seedling growth and have elevated EIN3 levels, even in the absence of exogenous ethylene. Collectively, our results show that the SCFEBF1/EBF2-dependent ubiquitination and subsequent removal of EIN3 is critical not only for proper ethylene signaling but also for growth in plants.