AUTHOR=Lee Hong Gil , Hong Cheljong , Seo Pil Joon 

TITLE=The Arabidopsis Sin3-HDAC Complex Facilitates Temporal Histone Deacetylation at the CCA1 and PRR9 Loci for Robust Circadian Oscillation

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.00171

DOI=10.3389/fpls.2019.00171

ISSN=1664-462X

ABSTRACT=<p>The circadian clock synchronizes endogenous rhythmic processes with environmental cycles and maximizes plant fitness. Multiple regulatory layers shape circadian oscillation, and chromatin modification is emerging as an important scheme for precise circadian waveforms. Here, we report the role of an evolutionarily conserved Sin3-histone deacetylase complex (HDAC) in circadian oscillation in <italic>Arabidopsis</italic>. <italic>SAP30 FUNCTION-RELATED 1</italic> (<italic>AFR1</italic>) and <italic>AFR2</italic>, which are key components of Sin3-HDAC complex, are circadianly-regulated and possibly facilitate the temporal formation of the <italic>Arabidopsis</italic> Sin3-HDAC complex at dusk. The evening-expressed AFR proteins bind directly to the <italic>CIRCADIAN CLOCK ASSOCIATED 1</italic> (<italic>CCA1</italic>) and <italic>PSEUDO-RESPONSE REGULATOR 9</italic> (<italic>PRR9</italic>) promoters and catalyze histone 3 (H3) deacetylation at the cognate regions to repress expression, allowing the declining phase of their expression at dusk. In support, the <italic>CCA1</italic> and <italic>PRR9</italic> genes were de-repressed around dusk in the <italic>afr1-1afr2-1</italic> double mutant. These findings indicate that periodic histone deacetylation at the morning genes by the Sin3-HDAC complex contributes to robust circadian maintenance in higher plants.</p>