title: A functional link between rhythmic changes in chromatin structure and the Arabidopsis biological clock.
abstract: Circadian clocks rhythmically coordinate biological processes in resonance with the environmental cycle. The clock function relies on negative feedback loops that generate 24-h rhythms in multiple outputs. In Arabidopsis thaliana, the clock component TIMING OF CAB EXPRESSION1 (TOC1) integrates the environmental information to coordinate circadian responses. Here, we use chromatin immunoprecipitation as well as physiological and luminescence assays to demonstrate that proper photoperiodic phase of TOC1 expression is important for clock synchronization of plant development with the environment. Our studies show that TOC1 circadian induction is accompanied by clock-controlled cycles of histone acetylation that favor transcriptionally permissive chromatin structures at the TOC1 locus. At dawn, TOC1 repression relies on the in vivo circadian binding of the clock component CIRCADIAN CLOCK ASSOCIATED1 (CCA1), while histone deacetylase activities facilitate the switch to repressive chromatin structures and contribute to the declining phase of TOC1 waveform around dusk. The use of cca1 late elongated hypocotyl double mutant and CCA1-overexpressing plants suggests a highly repressing function of CCA1, antagonizing H3 acetylation to regulate TOC1 mRNA abundance. The chromatin remodeling activities relevant at the TOC1 locus are distinctively modulated by photoperiod, suggesting a mechanism by which the clock sets the phase of physiological and developmental outputs.
authors.affiliation: Consorcio Consejo Superior de Investigaciones Científicas-Institut de Recerca i Tecnología Agroalimentarias, Laboratory of Plant Molecular Genetics, Institute of Molecular Biology, 08034 Barcelona, Spain.
authors.forename: Mariano
authors.initials: M
authors.lastname: Perales
authors.forename: Paloma
authors.initials: P
authors.lastname: Más
mesh_terms: D000107:Acetylation / Q000187:drug effects; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D002352:Carrier Proteins / Q000235:genetics; D002843:Chromatin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly / Q000235:genetics / Q000502:physiology*; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006877:Hydroxamic Acids / Q000494:pharmacology; D045342:Light-Harvesting Protein Complexes; D008156:Luciferases / Q000378:metabolism; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism; D017440:Photoperiod; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C423618:CAB2 protein, Arabidopsis; C114425:CCA1 protein, Arabidopsis; D002352:Carrier Proteins; D002843:Chromatin; D006657:Histones; D006877:Hydroxamic Acids; D045342:Light-Harvesting Protein Complexes; D009687:Nuclear Proteins; D012333:RNA, Messenger; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors; C012589:trichostatin A; D008156:Luciferases; D006655:Histone Deacetylases