title: Calcium-dependent oligomerization of CAR proteins at cell membrane modulates ABA signaling.
abstract: Regulation of ion transport in plants is essential for cell function. Abiotic stress unbalances cell ion homeostasis, and plants tend to readjust it, regulating membrane transporters and channels. The plant hormone abscisic acid (ABA) and the second messenger Ca(2+) are central in such processes, as they are involved in the regulation of protein kinases and phosphatases that control ion transport activity in response to environmental stimuli. The identification and characterization of the molecular mechanisms underlying the effect of ABA and Ca(2+) signaling pathways on membrane function are central and could provide opportunities for crop improvement. The C2-domain ABA-related (CAR) family of small proteins is involved in the Ca(2+)-dependent recruitment of the pyrabactin resistance 1/PYR1-like (PYR/PYL) ABA receptors to the membrane. However, to fully understand CAR function, it is necessary to define a molecular mechanism that integrates Ca(2+) sensing, membrane interaction, and the recognition of the PYR/PYL interacting partners. We present structural and biochemical data showing that CARs are peripheral membrane proteins that functionally cluster on the membrane and generate strong positive membrane curvature in a Ca(2+)-dependent manner. These features represent a mechanism for the generation, stabilization, and/or specific recognition of membrane discontinuities. Such structures may act as signaling platforms involved in the recruitment of PYR/PYL receptors and other signaling components involved in cell responses to stress.
authors.affiliation: Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, ES-28006 Madrid, Spain;
authors.forename: Maira
authors.initials: M
authors.lastname: Diaz
authors.affiliation: Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, ES-28006 Madrid, Spain;
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Sanchez-Barrena
authors.affiliation: Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, ES-28006 Madrid, Spain;
authors.forename: Juana Maria
authors.initials: JM
authors.lastname: Gonzalez-Rubio
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain;
authors.forename: Lesia
authors.initials: L
authors.lastname: Rodriguez
authors.affiliation: European Molecular Biology Laboratory (EMBL), Grenoble Outstation and Unit of Virus Host-Cell Interactions, Universite Joseph Fourier-EMBL-Centre National de la Recherche Scientifique, 38042, Grenoble Cedex 9, France;
authors.forename: Daniel
authors.initials: D
authors.lastname: Fernandez
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain;
authors.forename: Regina
authors.initials: R
authors.lastname: Antoni
authors.affiliation: Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, ES-28006 Madrid, Spain;
authors.forename: Cristina
authors.initials: C
authors.lastname: Yunta
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain;
authors.forename: Borja
authors.initials: B
authors.lastname: Belda-Palazon
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain;
authors.forename: Miguel
authors.initials: M
authors.lastname: Gonzalez-Guzman
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain;
authors.forename: Marta
authors.initials: M
authors.lastname: Peirats-Llobet
authors.affiliation: Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, ES-28006 Madrid, Spain;
authors.forename: Margarita
authors.initials: M
authors.lastname: Menendez
authors.affiliation: Electron Microscopy Unit, Structural Biology and Biocomputing Program, Spanish National Cancer Research Centre, 28029 Madrid, Spain.
authors.forename: Jasminka
authors.initials: J
authors.lastname: Boskovic
authors.affiliation: European Molecular Biology Laboratory (EMBL), Grenoble Outstation and Unit of Virus Host-Cell Interactions, Universite Joseph Fourier-EMBL-Centre National de la Recherche Scientifique, 38042, Grenoble Cedex 9, France;
authors.forename: Jose A
authors.initials: JA
authors.lastname: Marquez
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, ES-46022 Valencia, Spain;
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Rodriguez
authors.affiliation: Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Científicas, ES-28006 Madrid, Spain; xalbert@iqfr.csic.es.
authors.forename: Armando
authors.initials: A
authors.lastname: Albert
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002151:Calorimetry; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D018360:Crystallography, X-Ray; D008954:Models, Biological; D010641:Phenotype; D010743:Phospholipids / Q000737:chemistry; D011485:Protein Binding / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D012996:Solutions; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010743:Phospholipids; D012996:Solutions; D000040:Abscisic Acid; D002118:Calcium
keywords: abiotic stress; ion transport; membrane biology; signaling