Interaction of Arabidopsis DET1 with CCA1 and LHY in Mediating Transcriptional Repression in the Plant Circadian Clock

Abstract

SUMMARY The COP10-DET1-DDB1 (CDD) complex is an evolutionarily conserved protein complex discovered for its role in the repression of photomorphogenesis in Arabidopsis, and is important in many cellular and developmental processes in both plants and animals. However, its molecular mode of action remains poorly understood. Here, we show that the CDD component, DET1, possesses transcriptional repression activity and physically interacts with two closely related MYB transcription factors, CCA1 and LHY, which are core components of the plant circadian clock. DET1 associates with the promoter of CCA1/LHY target genes, such as TOC1, in a CCA1/LHY-dependent manner and is required for their repression, suggesting a recruitment of DET1 by the central oscillator components to regulate the clock. Our results reveal DET1 as a core transcriptional repression factor important for clock progression. Overall, the CDD complex may function as a transcriptional co-repressor in diverse processes through direct interaction with distinct transcription factors.

Direct Repression of Evening Genes by CIRCADIAN CLOCK-ASSOCIATED1 in the Arabidopsis Circadian Clock

“…This work demonstrates that CCA1 and LHY also repress transcription of PRR5, PRR7, and PRR9 (Figures 2 and 5). CCA1 and LHY apparently regulate gene transcription by interacting with other classes of regulators like DET1 as a corepressor for TOC1 transcription (Lau et al, 2011). This type of property may give CCA1 and LHY molecular plasticity (i.e., as a weak or strong repressor or activator of transcription) with regulatory control in a contextdependent manner.…”

“…Two single Myb-related TFs, CIRCADIAN CLOCK-ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), directly repress expression of TIMING OF CAB EXPRESSION1 (TOC1), EARLY FLOWERING4 (ELF4), and LUXARRHYTHMO (LUX), all of which are expressed during the evening hours (Alabadí et al, 2001;Hazen et al, 2005;Perales and Más, 2007;Li et al, 2011). CCA1 and LHY repress such target genes through the corepressor DE-ETIOLATED1 (DET1) (Lau et al, 2011). CCA1 and LHY are required for activating expression of PSEUDO-RESPONSE REGULATOR9 (PRR9) and PRR7 (Farré et al, 2005), but the molecular details of this activation remain unknown.…”

Circadian Clock and Photoperiodic Flowering in Arabidopsis: CONSTANS Is a Hub for Signal Integration

“…At dawn, two MYB transcription factors, CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), repress evening-phased genes (Nagel et al, 2015;Kamioka et al, 2016). This repression is partly dependent on the function of the CONSTITUTIVE PHOTOMORPHOGENIC10 (COP10)-DE-ETIOLATED1-DAMAGED DNA BINDING1 complex, a negative regulator for photomorphogenesis (Lau et al, 2011). To repress transcription, CCA1 and LHY bind to related cis-elements called Evening Element and the CCA1 Binding Site .…”

Transcriptional corepressor TOPLESS complexes with pseudoresponse regulator proteins and histone deacetylases to regulate circadian transcription

“…TOC1 is the founding member of five closely related PSEUDO RESPONSE REGULATORS (PRRs: PRR9, PRR7, PRR5, PRR3) and binds DNA through a conserved CCT domain at the carboxy terminus, repressing evening expression of both CCA1 and LHY (7,8). The mechanism of CCA1/LHY-mediated repression of TOC1 requires the corepressor DE-ETIOLATED1 (DET1) to interact with CCA1 and LHY at the TOC1promoter, likely in the context of a larger COP10-DET1-DDB1(CDD) complex (9). TOC1 is also regulated by the related myb-transcription factor, REV8, which binds the TOC1 promoter and likely acts as a positive activator (10,11).…”