title: Processing and subcellular trafficking of ER-tethered EIN2 control response to ethylene gas.
abstract: Ethylene gas is essential for many developmental processes and stress responses in plants. ETHYLENE INSENSITIVE2 (EIN2), an NRAMP-like integral membrane protein, plays an essential role in ethylene signaling, but its function remains enigmatic. Here we report that phosphorylation-regulated proteolytic processing of EIN2 triggers its endoplasmic reticulum (ER)-to-nucleus translocation. ER-tethered EIN2 shows CONSTITUTIVE TRIPLE RESPONSE1 (CTR1) kinase-dependent phosphorylation. Ethylene triggers dephosphorylation at several sites and proteolytic cleavage at one of these sites, resulting in nuclear translocation of a carboxyl-terminal EIN2 fragment (EIN2-C'). Mutations that mimic EIN2 dephosphorylation, or inactivate CTR1, show constitutive cleavage and nuclear localization of EIN2-C' and EIN3 and EIN3-LIKE1-dependent activation of ethylene responses. These findings uncover a mechanism of subcellular communication whereby ethylene stimulates phosphorylation-dependent cleavage and nuclear movement of the EIN2-C' peptide, linking hormone perception and signaling components in the ER with nuclear-localized transcriptional regulators.
authors.affiliation: Plant Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
authors.forename: Hong
authors.initials: H
authors.lastname: Qiao
authors.forename: Zhouxin
authors.initials: Z
authors.lastname: Shen
authors.forename: Shao-shan Carol
authors.initials: SS
authors.lastname: Huang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schmitz
authors.forename: Mark A
authors.initials: MA
authors.lastname: Urich
authors.forename: Steven P
authors.initials: SP
authors.lastname: Briggs
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Ecker
mesh_terms: D021581:Active Transport, Cell Nucleus; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005030:Ethylenes / Q000378:metabolism* / Q000494:pharmacology; D005740:Gases / Q000378:metabolism / Q000494:pharmacology; D009154:Mutation; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D059748:Proteolysis; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C119963:EIN2 protein, Arabidopsis; D005030:Ethylenes; D005740:Gases; D019913:Nuclear Localization Signals; D011956:Receptors, Cell Surface; C036216:ethylene; D011494:Protein Kinases; C477753:CTR1 protein, Arabidopsis