The DREAM complex antagonizes WDR5a and represses the productive elongation of transcription in Arabidopsis [ChIP-seq]

The master transcriptional repressor DREAM (dimerization partner, RB-like, E2F and multi-vulval class B) complex regulates cell cycle in eukaryotes, but much remains unknown about how it transmits repressive signals on chromatin to the primary transcriptional machinery (e.g., Pol II). Through a genetic screen, we identified BTE1 (barrier of transcription elongation 1), a key component in the plant DREAM complex. The subsequent characterization demonstrated that the DREAM complex represses Pol II elongation. The core DREAM subunits E2F transcription factors recruit BTE1 to accumulate at the promoter-proximal regions of target genes. DREAM target genes exhibit characteristic enrichment of H2A.Z and H3K4me2 modification on chromatin. The DREAM complex BTE1 subunit interacts with WDR5a, repressing WDR5a chromatin binding and the productive elongation of transcription on BTE1-targeted genomic loci. Thus, we demonstrate a major role of DREAM complex in the control of transition from transcription initiation to productive elongation around TSSs on the open chromatin via inhibiting WDR5a function. Three biological replicates of each genotype were used for high-throughput sequencing analysis. All experiments wer conducted using 9-day-old seedlings grown in continuous white light.