Dataset Information

The Arabidopsis NuA4 histone acetyltransferase complex is required for chlorophyll biosynthesis and photosynthesis. [ChIP-Seq]

ABSTRACT: Although two Enhancer of Polycomb-like proteins, EPL1A and EPL1B (EPL1A/B), are known to be conserved and characteristic subunits of the NuA4-type histone acetyltransferase complex in Arabidopsis thaliana, the biological function of EPL1A/B and the mechanism by which EPL1A/B function in the complex remain unknown. Here, we report that EPL1A/B are required for the histone acetyltransferase activity of the NuA4 complex on the nucleosomal histone H4 in vitro and for the enrichment of histone H4K5 acetylation at thousands of protein-coding genes in vivo. We demonstrate that EPL1A/B are required for linking the NuA4 catalytic subunit HAM1 with accessory subunits in the NuA4 complex. EPL1A/B function redundantly in regulating plant development especially in chlorophyll biosynthesis and de-etiolation. The EPL1A/B-dependent transcription and H4K5Ac are enriched at genes involved in chlorophyll biosynthesis and photosynthesis. We also find that EAF6, another characteristic subunit of the NuA4 complex, contribute to de-etiolation. These results suggest that the Arabidopsis NuA4 complex components function as a whole to mediate histone acetylation and transcriptional activation specifically at light-responsive genes and are critical for photomorphogenesis.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE193793 | GEO | 2022/01/20

REPOSITORIES: GEO

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Project description:Post-translational modifications (PTMs) on histones have been found to play diverse functions in regulating chromatin events and gene expression. The operation of circadian clocks heavily relies on finely tuned and timely expression of the proteins comprising core oscillators. However, most studies of PTMs’ effects on circadian clocks have been conducted using static systems in which circadian clocks are rendered arrhythmic due to the essential role of PTMs on gene expression. In the Neurospora circadian system, the White Collar Complex (WCC), a heterodimeric transcription factor formed from White Collar-1 (WC-1) and White Collar-2 (WC-2), serves the function of the BMAL1/CLOCK heterodimer in mammals, driving expression of circadian negative arm component(s), a principal one in Neurospora encoded by the gene frequency (frq). FRQ interacts with FRH (FRQ-interacting helicase) and CK-1 forming a stable complex that represses its own expression by inhibiting WCC. In this study, a genetic screen identified a gene, designated as brd-8, that encodes a conserved auxiliary subunit of the NuA4 histone acetylation complex. Loss of brd-8 reduces H4 acetylation and RNA polymerase (Pol) II occupancy at frq and other known circadian genes, and leads to a long circadian period, delayed phase, and defective overt circadian output at some temperatures. In addition to strongly associating with the NuA4 histone acetyltransferase complex, BRD-8 is also found complexed with the transcription elongation regulator BYE-1. Expression of brd-8, bye-1, histone hH2Az, and several NuA4 subunits is controlled by the circadian clock, indicating that the molecular clock both regulates the basic chromatin status and is regulated by changes in chromatin. Taken together, our data identify new auxiliary elements of the fungal NuA4 complex having homology to mammalian components, which along with conventional NuA4 subunits, are required for timely and dynamic frq expression and thereby a normal and persistent circadian rhythm.

Project description:Post-translational modifications (PTMs) on histones have been found to play diverse functions in regulating chromatin events and gene expression. The operation of circadian clocks heavily relies on finely tuned and timely expression of the proteins comprising core oscillators. However, most studies of PTMs' effects on circadian clocks have been conducted using static systems in which circadian clocks are rendered arrhythmic due to the essential role of PTMs on gene expression. In the Neurospora circadian system, the White Collar Complex (WCC), a heterodimeric transcription factor formed from White Collar-1 (WC-1) and White Collar-2 (WC-2), serves the function of the BMAL1/CLOCK heterodimer in mammals, driving expression of circadian negative arm component(s), a principal one in Neurospora encoded by the gene frequency (frq). FRQ interacts with FRH (FRQ-interacting helicase) and CK-1 forming a stable complex that represses its own expression by inhibiting WCC. In this study, a genetic screen identified a gene, designated as eaf-8, that encodes a novel conserved subunit of the NuA4 histone acetylation complex. Loss of eaf-8 reduces H4 acetylation and RNA polymerase (Pol) II occupancy at frq and other known circadian genes, and leads to a long circadian period, delayed phase, and defective overt circadian output at some temperatures. In addition to strongly associating with the NuA4 histone acetyltransferase complex, EAF-8 is also found complexed with the transcription elongation regulator BYE-1. Expression of eaf-8, bye-1, histone hH2Az, and several NuA4 subunits is controlled by the circadian clock, indicating that the molecular clock both regulates the basic chromatin status and is regulated by changes in chromatin. Taken together, our data identify a new type of the NuA4 complex including EAF-8 and BYE-1 which, along with conventional NuA4 subunits, is required for timely and dynamic frq expression and thereby a normal and persistent circadian rhythm.