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Curr Biol. 2011 Jan 25;21(2):120-5. doi: 10.1016/j.cub.2010.12.013. Epub 2011 Jan 13.

Temporal repression of core circadian genes is mediated through EARLY FLOWERING 3 in Arabidopsis.

Author information

1
Centre of Systems Biology at Edinburgh, University of Edinburgh, Edinburgh, Midlothian EH9 3JD, UK.

Abstract

The circadian clock provides robust, ∼24 hr biological rhythms throughout the eukaryotes. The clock gene circuit in plants comprises interlocking transcriptional feedback loops, reviewed in [1], whereby the morning-expressed transcription factors CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) repress the expression of evening genes, notably TIMING OF CAB EXPRESSION 1 (TOC1). EARLY FLOWERING 3 (ELF3) has been implicated as a repressor of light signaling to the clock [2, 3] and, paradoxically, as an activator of the light-induced genes CCA1 and LHY [4, 5]. We use cca1-11 lhy-21 elf3-4 plants to separate the repressive function of ELF3 from its downstream targets CCA1 and LHY. We further demonstrate that ELF3 associates physically with the promoter of PSEUDO-RESPONSE REGULATOR 9 (PRR9), a repressor of CCA1 and LHY expression, in a time-dependent fashion. The repressive function of ELF3 is thus consistent with indirect activation of LHY and CCA1, in a double-negative connection via a direct ELF3 target, PRR9. This mechanism reconciles the functions of ELF3 in the clock network during the night and points to further effects of ELF3 during the day.

PMID:
21236675
PMCID:
PMC3028277
DOI:
10.1016/j.cub.2010.12.013
[Indexed for MEDLINE]
Free PMC Article

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