Interaction of RSC Chromatin Remodeling Complex with Nucleosomes Is Modulated by H3 K14 Acetylation and H2B SUMOylation In Vivo

Chromatin remodeling complexes are multi-subunit nucleosome translocases that reorganize chromatin in the context of DNA replication, repair, and transcription. To understand how these complexes find their target sites on chromatin, we use genetically encoded photo-cross-linker amino acids to map the footprint of Sth1, the catalytic subunit of the RSC complex, on nucleosomes in living yeast. We find that H3 K14 acetylation induces the interaction of the Sth1 bromodomain with the H3 tail and mediates the interaction of RSC with neighboring nucleosomes rather than recruiting it to chromatin. RSC preferentially resides on H2B SUMOylated nucleosomes in vivo and shows a moderately enhanced affinity due to this modification in vitro. Furthermore, RSC is not ejected from chromatin in mitosis, but changes its mode of nucleosome binding. Our in vivo analyses show that RSC recruitment to specific chromatin targets involves multiple histone modifications likely in combination with histone variants and transcription factors.