Uncertainty of EIN2Ser645/Ser924 Inactivation by CTR1-Mediated Phosphorylation Reveals the Complexity of Ethylene Signaling

摘要: Abstract ETHYLENE INSENSITIVE2 (EIN2) is a key component of ethylene signaling whose activity inhibited upon phosphorylation Ser645 and Ser924 by the Raf-like CONSTITUTIVE TRIPLE-RESPONSE 1 (CTR1) in absence ethylene. Ethylene prevents CTR1 thus EIN2Ser645/Ser924 phosphorylation, subcellular trafficking proteolytically cleaved EIN2 C terminus (EIN2-C) from endoplasmic reticulum to nucleus processing bodies triggers signaling. Here, we report an unexpected complexity EIN2-activated activation part requires CTR1-mediated negative regulation. The ein2 mutant was complemented transgenes encoding EIN2, variants with mutations that either prevent or mimic Ser645/Ser924 EIN2-C; all the transgenic lines carrying these EIN2-derived responded Furthermore, found fluorescence protein-tagged its were affected little exhibited similar distribution patterns: cytosolic particles nuclear speckles. Of note, localization patterns proteins fused protein at N or similar, whereas EIN2-C-YFP primarily observed cytosol but not nucleus. Western blots mass spectrum analyses suggested high which likely processed into multiple fragments. Our results full-length weak association EIN2Ser645/Ser924 status signaling, caused proteolytic products different compartments. We propose alternative model explain