Ethylene insensitive 2 （EIN2）, an integral membrane protein of the ER network, has been identified as the central regulator of the ethylene signaling pathway. Still, the mechanism by which the ethylene signal is tra...Ethylene insensitive 2 （EIN2）, an integral membrane protein of the ER network, has been identified as the central regulator of the ethylene signaling pathway. Still, the mechanism by which the ethylene signal is transferred from the receptors to EIN2 has not been solved yet. Here, we show that protein phosphorylation is a key mechanism to control the interaction of EIN2 and the receptors. In vivo and in vitro fluorescence studies reveal that the kinase domain of the receptors is essential for the interaction. Cyanide, an ethylene agonist, which is known to reduce auto-phosphorylation of the ethylene receptor ethylene resistant 1 （ETR1） or a mutation in the kinase domain of ETR1 that prevents autophosphorylation （H353A）, increases the affinity of the receptors for EIN2. On the other hand, mimicking permanent auto-phosphorylation of ETR1 as in the mutant H353E releases the EiN2-ETR1 interaction from the control by the plant hormone. Based on our data, we propose a novel model on the integration of EIN2 in the ethylene signaling cascade.展开更多
The gaseous plant hormone ethylene regulates many processes of high agronomic relevance throughout the life span of plants. A central element in ethylene signaling is the endoplasmic reticulum （ER）-Iocalized membran...The gaseous plant hormone ethylene regulates many processes of high agronomic relevance throughout the life span of plants. A central element in ethylene signaling is the endoplasmic reticulum （ER）-Iocalized membrane protein ETHYLENE INSENSITIVE2 （EIN2）. Recent studies indicate that in response to ethylene, the extra-membranous C-terminal end of EIN2 is proteolytically processed and translocated from the ER to the nucleus. Here, we report that the conserved nuclear localization signal （NLS） mediating nuclear import of the EIN2 C-terminus provides an important domain for complex formation with ethylene receptor ETHYLENE RESPONSE1 （ETR1）. EIN2 lacking the NLS domain shows strongly reduced affinity for the receptor. Interaction of EIN2 and ETR1 is also blocked by a synthetic peptide of the NLS motif. The corre- sponding peptide substantially reduces ethylene responses in planta. Our results uncover a novel mecha- nism and type of inhibitor interfering with ethylene signal transduction and ethylene responses in plants. Disruption of essential protein-protein interactions in the ethylene signaling pathway as shown in our study for the EIN2-ETR1 complex has the potential to guide the development of innovative ethylene antagonists for modern agriculture and horticulture.展开更多
文摘Ethylene insensitive 2 （EIN2）, an integral membrane protein of the ER network, has been identified as the central regulator of the ethylene signaling pathway. Still, the mechanism by which the ethylene signal is transferred from the receptors to EIN2 has not been solved yet. Here, we show that protein phosphorylation is a key mechanism to control the interaction of EIN2 and the receptors. In vivo and in vitro fluorescence studies reveal that the kinase domain of the receptors is essential for the interaction. Cyanide, an ethylene agonist, which is known to reduce auto-phosphorylation of the ethylene receptor ethylene resistant 1 （ETR1） or a mutation in the kinase domain of ETR1 that prevents autophosphorylation （H353A）, increases the affinity of the receptors for EIN2. On the other hand, mimicking permanent auto-phosphorylation of ETR1 as in the mutant H353E releases the EiN2-ETR1 interaction from the control by the plant hormone. Based on our data, we propose a novel model on the integration of EIN2 in the ethylene signaling cascade.
文摘The gaseous plant hormone ethylene regulates many processes of high agronomic relevance throughout the life span of plants. A central element in ethylene signaling is the endoplasmic reticulum （ER）-Iocalized membrane protein ETHYLENE INSENSITIVE2 （EIN2）. Recent studies indicate that in response to ethylene, the extra-membranous C-terminal end of EIN2 is proteolytically processed and translocated from the ER to the nucleus. Here, we report that the conserved nuclear localization signal （NLS） mediating nuclear import of the EIN2 C-terminus provides an important domain for complex formation with ethylene receptor ETHYLENE RESPONSE1 （ETR1）. EIN2 lacking the NLS domain shows strongly reduced affinity for the receptor. Interaction of EIN2 and ETR1 is also blocked by a synthetic peptide of the NLS motif. The corre- sponding peptide substantially reduces ethylene responses in planta. Our results uncover a novel mecha- nism and type of inhibitor interfering with ethylene signal transduction and ethylene responses in plants. Disruption of essential protein-protein interactions in the ethylene signaling pathway as shown in our study for the EIN2-ETR1 complex has the potential to guide the development of innovative ethylene antagonists for modern agriculture and horticulture.
