Covalent Modifications of Histone H3K9 Promote Binding of CHD3

Chromatin remodeling is required for genome function and is facilitated by ATP-dependent complexes, such as nucleosome remodeling and deacetylase (NuRD). Among its core components is the chromodomain helicase DNA binding protein 3 (CHD3) whose functional significance is not well established. Here, we show that CHD3 co-localizes with the other NuRD subunits, including HDAC1, near the H3K9ac-enriched promoters of the NuRD target genes. The tandem PHD fingers of CHD3 bind histone H3 tails and posttranslational modifications that increase hydrophobicity of H3K9—methylation or acetylation (H3K9me3 or H3K9ac)—enhance this interaction. Binding of CHD3 PHDs promotes H3K9Cme3-nucleosome unwrapping in vitro and perturbs the pericentric heterochromatin structure in vivo. Methylation or acetylation of H3K9 uniquely alleviates the intra-nucleosomal interaction of histone H3 tails, increasing H3K9 accessibility. Collectively, our data suggest that the targeting of covalently modified H3K9 by CHD3 might be essential in diverse functions of NuRD. [Display omitted] •CHD3 occupies H3K9ac-enriched promoters of NuRD target genes•PTMs that increase hydrophobicity of H3K9 enhance binding of the PHD fingers of CHD3•Methylation or acetylation of H3K9 increases H3 tail accessibility•Targeting of modified H3K9 by CHD3 might be essential for diverse NuRD functions Tencer et al. find that CHD3 co-localizes with the other subunits of the NuRD complex and H3K9ac at NuRD target genes. The authors further demonstrate that the PHD fingers of CHD3 associate with histone H3 tails, and this association is augmented through methylation or acetylation of H3K9.