title: The RNA-binding protein FCA is an abscisic acid receptor.
abstract: The phytohormone abscisic acid (ABA) regulates various physiological processes in plants. The molecular mechanisms by which this is achieved are not fully understood. Genetic approaches have characterized several downstream components of ABA signalling, but a receptor for ABA has remained elusive. Although studies indicate that several ABA response genes encode RNA-binding or RNA-processing proteins, none has been found to be functional in binding ABA. Here we show that FCA, an RNA-binding protein involved in flowering, binds ABA with high affinity in an interaction that is stereospecific and follows receptor kinetics. The interaction between FCA and ABA has molecular effects on downstream events in the autonomous floral pathway and, consequently, on the ability of the plant to undergo transition to flowering. We further show that ABA binding exerts a direct control on the FCA-mediated processing of precursor messenger RNA. Our results indicate that FCA is an ABA receptor involved in RNA metabolism and in controlling flowering time.
authors.affiliation: Department of Plant Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Fawzi A
authors.initials: FA
authors.lastname: Razem
authors.forename: Ashraf
authors.initials: A
authors.lastname: El-Kereamy
authors.forename: Suzanne R
authors.initials: SR
authors.lastname: Abrams
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hill
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D035264:Flowers / Q000187:drug effects / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C106535:Flowering time control protein FCA, Arabidopsis; D016601:RNA-Binding Proteins; D000040:Abscisic Acid