title: Heteromeric interactions among ethylene receptors mediate signaling in Arabidopsis.
abstract: The gaseous hormone ethylene is perceived in Arabidopsis by a five member receptor family that consists of the subfamily 1 receptors ETR1 and ERS1 and the subfamily 2 receptors ETR2, ERS2, and EIN4. Previous work has demonstrated that the basic functional unit for the ethylene receptor, ETR1, is a disulfide-linked homodimer. We demonstrate here that ethylene receptors isolated from Arabidopsis also interact with each other through noncovalent interactions. Evidence that ETR1 associates with other ethylene receptors was obtained by co-purification of ETR1 with tagged versions of ERS1, ETR2, ERS2, and EIN4 from Arabidopsis membrane extracts. ETR1 preferentially associated with the subfamily 2 receptors compared with the subfamily 1 receptor ERS1, but ethylene treatment affected the interactions and relative composition of the receptor complexes. When transgenically expressed in yeast, ETR1 and ERS2 can form disulfide-linked heterodimers. In plant extracts, however, the association of ETR1 and ERS2 can be largely disrupted by treatment with SDS, supporting a higher order noncovalent interaction between the receptors. Yeast two-hybrid analysis demonstrated that the receptor GAF domains are capable of mediating heteromeric receptor interactions. Kinetic analysis of ethylene-insensitive mutants of ETR1 is consistent with their dominance being due in part to an ability to associate with other ethylene receptors. These data suggest that the ethylene receptors exist in plants as clusters in a manner potentially analogous to that found with the histidine kinase-linked chemoreceptors of bacteria and that interactions among receptors contribute to ethylene signal output.
authors.affiliation: Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Gao
authors.forename: Chi-Kuang
authors.initials: CK
authors.lastname: Wen
authors.forename: Brad M
authors.initials: BM
authors.lastname: Binder
authors.forename: Yi-Feng
authors.initials: YF
authors.lastname: Chen
authors.forename: Jianhong
authors.initials: J
authors.lastname: Chang
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Chiang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kerris
authors.forename: Caren
authors.initials: C
authors.lastname: Chang
authors.forename: G Eric
authors.initials: GE
authors.lastname: Schaller
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D011485:Protein Binding / Q000502:physiology; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D004220:Disulfides; C114576:EIN4 protein, Arabidopsis; C517775:ERS1 protein, Arabidopsis; C494590:ETR1 protein, Arabidopsis; D011956:Receptors, Cell Surface