title: Structural model of the cytosolic domain of the plant ethylene receptor 1 (ETR1).
abstract: Ethylene initiates important aspects of plant growth and development through disulfide-linked receptor dimers located in the endoplasmic reticulum. The receptors feature a small transmembrane, ethylene binding domain followed by a large cytosolic domain, which serves as a scaffold for the assembly of large molecular weight complexes of different ethylene receptors and other cellular participants of the ethylene signaling pathway. Here we report the crystallographic structures of the ethylene receptor 1 (ETR1) catalytic ATP-binding and the ethylene response sensor 1 dimerization histidine phosphotransfer (DHp) domains and the solution structure of the entire cytosolic domain of ETR1, all from Arabidopsis thaliana. The isolated dimeric ethylene response sensor 1 DHp domain is asymmetric, the result of different helical bending angles close to the conserved His residue. The structures of the catalytic ATP-binding, DHp, and receiver domains of ethylene receptors and of a homologous, but dissimilar, GAF domain were refined against experimental small angle x-ray scattering data, leading to a structural model of the entire cytosolic domain of the ethylene receptor 1. The model illustrates that the cytosolic domain is shaped like a dumbbell and that the receiver domain is flexible and assumes a position different from those observed in prokaryotic histidine kinases. Furthermore the cytosolic domain of ETR1 plays a key role, interacting with all other receptors and several participants of the ethylene signaling pathway. Our model, therefore, provides the first step toward a detailed understanding of the molecular mechanics of this important signal transduction process in plants.
authors.affiliation: From the European Molecular Biology Laboratory (EMBL) Hamburg, c/o Deutsches Elektronen-Synchrotron (DESY), Building 25A, Notkestrasse 85, 22603 Hamburg, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Mayerhofer
authors.affiliation: From the European Molecular Biology Laboratory (EMBL) Hamburg, c/o Deutsches Elektronen-Synchrotron (DESY), Building 25A, Notkestrasse 85, 22603 Hamburg, Germany.
authors.forename: Saravanan
authors.initials: S
authors.lastname: Panneerselvam
authors.affiliation: From the European Molecular Biology Laboratory (EMBL) Hamburg, c/o Deutsches Elektronen-Synchrotron (DESY), Building 25A, Notkestrasse 85, 22603 Hamburg, Germany.
authors.forename: Heidi
authors.initials: H
authors.lastname: Kaljunen
authors.affiliation: From the European Molecular Biology Laboratory (EMBL) Hamburg, c/o Deutsches Elektronen-Synchrotron (DESY), Building 25A, Notkestrasse 85, 22603 Hamburg, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Tuukkanen
authors.affiliation: From the European Molecular Biology Laboratory (EMBL) Hamburg, c/o Deutsches Elektronen-Synchrotron (DESY), Building 25A, Notkestrasse 85, 22603 Hamburg, Germany.
authors.forename: Haydyn D T
authors.initials: HD
authors.lastname: Mertens
authors.affiliation: From the European Molecular Biology Laboratory (EMBL) Hamburg, c/o Deutsches Elektronen-Synchrotron (DESY), Building 25A, Notkestrasse 85, 22603 Hamburg, Germany jochen.mueller-dieckmann@uni-hamburg.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Mueller-Dieckmann
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D018360:Crystallography, X-Ray; D003600:Cytosol / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism
chemical_list: D005030:Ethylenes; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C083750:ethylene receptors, plant; C036216:ethylene
keywords: Arabidopsis thaliana; Crystal Structure; Ethylene Receptor; Histidine Kinase; Plant Hormone; Small Angle X-ray Scattering (SAXS); Two-component System