POWERDRESS and HDA9 interact and promote histone H3 deacetylation at specific genomic sites in Arabidopsis

Dec 9, 2016Proceedings of the National Academy of Sciences of the United States of America

POWERDRESS and HDA9 work together to reduce gene activity by removing chemical tags in specific parts of the Arabidopsis genome

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Abstract

POWERDRESS (PWR) promotes histone H3 deacetylation by interacting with HDA9.

PWR interacts with HDA9, potentially enhancing its ability to remove acetyl groups from histone H3.
Both pwr and hda9 mutants exhibit similar developmental phenotypes.
Acetylation levels of histone H3 at residues K9, K14, and K27 remain high in pwr and hda9 mutants.
Genome-wide profiling shows increased acetylation at overlapping target genes in both mutants.
Similar gene-expression profiles in pwr and hda9 mutants correspond with their histone H3 acetylation status.
PWR and HDA9 influence flowering time by repressing AGAMOUS-LIKE 19 expression through histone deacetylation.

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Histone acetylation is a major epigenetic control mechanism that is tightly linked to the promotion of gene expression. Histone acetylation levels are balanced through the opposing activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Arabidopsis HDAC genes (AtHDACs) compose a large gene family, and distinct phenotypes among AtHDAC mutants reflect the functional specificity of individual AtHDACs However, the mechanisms underlying this functional diversity are largely unknown. Here, we show that POWERDRESS (PWR), a SANT (SWI3/DAD2/N-CoR/TFIII-B) domain protein, interacts with HDA9 and promotes histone H3 deacetylation, possibly by facilitating HDA9 function at target regions. The developmental phenotypes of pwr and hda9 mutants were highly similar. Three lysine residues (K9, K14, and K27) of H3 retained hyperacetylation status in both pwr and hda9 mutants. Genome-wide H3K9 and H3K14 acetylation profiling revealed elevated acetylation at largely overlapping sets of target genes in the two mutants. Highly similar gene-expression profiles in the two mutants correlated with the histone H3 acetylation status in the pwr and hda9 mutants. In addition, PWR and HDA9 modulated flowering time by repressing AGAMOUS-LIKE 19 expression through histone H3 deacetylation in the same genetic pathway. Finally, PWR was shown to physically interact with HDA9, and its SANT2 domain, which is homologous to that of subunits in animal HDAC complexes, showed specific binding affinity to acetylated histone H3. We therefore propose that PWR acts as a subunit in a complex with HDA9 to result in lysine deacetylation of histone H3 at specific genomic targets.

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POWERDRESS and HDA9 interact and promote histone H3 deacetylation at specific genomic sites in Arabidopsis

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