GSE21615
Genomic maps of homotypic H2Av, heterotypic H2Av, input and 80mM salt soluble chromatin from Drosophila S2 cells
Nucleosomes that contain the histone variant H2A.Z are enriched around transcriptional start sites in many organisms. A single octameric nucleosome can contain two H2A.Z histones (homotypic) or one H2A.Z and one canonical H2A (heterotype). We generated high-resolution maps of homotypic and heterotypic Drosophila H2A.Z (H2Av) nucleosomes. Although homotypic and heterotypic H2Av nucleosomes map throughout most of the genome, homotypic nucleosomes are enriched and heterotypic nucleosomes are depleted downstream of active promoters and intron/exon boundaries. The distribution of homotypic H2A.Z nucleosomes resembles that of salt-soluble nucleosomes and shows evidence of displacement during transcriptional elongation. Homotypic nucleosomes are also depleted downstream of paused polymerases, where salt-soluble nucleosomes are conspicuously depleted. Our results suggest a model whereby H2A.Z enrichment patterns result from different structural interactions within the core of heterotypic and homotypic nucleosomes following disruption during transcriptional elongation. Overall design: We analyzed two replicates for input, heterotypic and homotypic purifications. We sequenced one library for each of the single H2Av pulldown and 80mM salt soluble samples.