title: Overlapping and distinct roles of PRR7 and PRR9 in the Arabidopsis circadian clock.
abstract: The core mechanism of the circadian oscillators described to date rely on transcriptional negative feedback loops with a delay between the negative and the positive components . In plants, the first suggested regulatory loop involves the transcription factors CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) and the pseudo-response regulator TIMING OF CAB EXPRESSION 1 (TOC1/PRR1). TOC1 is a member of the Arabidopsis circadian-regulated PRR gene family . Analysis of single and double mutants in PRR7 and PRR9 indicates that these morning-expressed genes play a dual role in the circadian clock, being involved in the transmission of light signals to the clock and in the regulation of the central oscillator. Furthermore, CCA1 and LHY had a positive effect on PRR7 and PRR9 expression levels, indicating that they might form part of an additional regulatory feedback loop. We propose that the Arabidopsis circadian oscillator is composed of several interlocking positive and negative feedback loops, a feature of clock regulation that appears broadly conserved between plants, fungi, and animals.
authors.affiliation: Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Farré
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Harmer
authors.forename: Frank G
authors.initials: FG
authors.lastname: Harmon
authors.forename: Marcelo J
authors.initials: MJ
authors.lastname: Yanovsky
authors.forename: Steve A
authors.initials: SA
authors.lastname: Kay
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001683:Biological Clocks / Q000235:genetics / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D025461:Feedback, Physiological / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D008954:Models, Biological; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D004268:DNA-Binding Proteins; C113192:LHY protein, Arabidopsis; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors