title: ETHYLENE-INSENSITIVE5 encodes a 5'-->3' exoribonuclease required for regulation of the EIN3-targeting F-box proteins EBF1/2.
abstract: Ethylene is a gaseous plant growth regulator that controls a multitude of developmental and stress responses. Recently, the levels of Arabidopsis EIN3 protein, a key transcription factor mediating ethylene-regulated gene expression, have been demonstrated to increase in response to the presence of ethylene gas. Furthermore, in the absence of ethylene, EIN3 is quickly degraded through a ubiquitin/proteasome pathway mediated by two F-box proteins, EBF1 and EBF2. Here we report the identification of ETHYLENE-INSENSITIVE5 as the 5'-->3' exoribonuclease XRN4. Specifically, we demonstrate that EIN5 is a component of the ethylene signal transduction cascade acting downstream of CTR1 that is required for ethylene-mediated gene expression changes. Furthermore, we find that the ethylene insensitivity of ein5 mutant plants is a consequence of the over-accumulation of EBF1 and EBF2 mRNAs resulting in the under-accumulation of EIN3 even in the presence of ethylene gas. Together, our results suggest that the role of EIN5 in ethylene perception is to antagonize the negative feedback regulation on EIN3 by promoting EBF1 and EBF2 mRNA decay, which consequently allows the accumulation of EIN3 protein to trigger the ethylene response.
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Olmedo
authors.forename: Hongwei
authors.initials: H
authors.lastname: Guo
authors.forename: Brian D
authors.initials: BD
authors.lastname: Gregory
authors.forename: Saeid D
authors.initials: SD
authors.lastname: Nourizadeh
authors.forename: Laura
authors.initials: L
authors.lastname: Aguilar-Henonin
authors.forename: Hongjiang
authors.initials: H
authors.lastname: Li
authors.forename: Fengying
authors.initials: F
authors.lastname: An
authors.forename: Plinio
authors.initials: P
authors.lastname: Guzman
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Ecker
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D032461:Chromosomes, Plant; D004268:DNA-Binding Proteins; D005030:Ethylenes / Q000378:metabolism*; D005095:Exoribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism*; D025461:Feedback, Physiological; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010802:Phylogeny; D020161:Physical Chromosome Mapping; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000235:genetics / Q000254:growth & development; D014157:Transcription Factors
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C481044:EBF1 protein, Arabidopsis; C481045:EBF2 protein, Arabidopsis; C106987:EIN3 protein, Arabidopsis; D005030:Ethylenes; D044783:F-Box Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D014157:Transcription Factors; C418137:Xrn1 protein, plant; C036216:ethylene; D005095:Exoribonucleases