The RSC complex remodels chromatin structure and regulates gene transcription. We used cryo–electron microscopy to determine the structure of yeast RSC bound to the nucleosome. RSC is delineated into the adenosine triphosphatase motor, the actin-related protein module, and the substrate recruitment module (SRM). RSC binds the nucleosome mainly through the motor, with the auxiliary subunit Sfh1 engaging the H2A-H2B acidic patch to enable nucleosome ejection. SRM is organized into three substrate-binding lobes poised to bind their respective nucleosomal epitopes. The relative orientations of the SRM and the motor on the nucleosome explain the directionality of DNA translocation and promoter nucleosome repositioning by RSC. Our findings shed light on RSC assembly and functionality, and they provide a framework to understand the mammalian homologs BAF/PBAF and the Sfh1 ortholog INI1/BAF47, which are frequently mutated in cancers.

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DNA in eukaryotes wraps around the histone octamer to form nucleosomes 1 , the fundamental unit of chromatin. The N-termini of histone H4 interact with nearby nucleosomes, and play an important role in the formation of high order chromatin structure and heterochromatin silencing 2-4 . NuA4 in yeast and its homolog Tip60 complex in mammalian cells are the key enzymes that catalyze H4 acetylation, which in turn regulate chromatin packaging, and function in transcription activation and DNA repair 5-10 . Here we report the cryo-EM structure of NuA4 from Saccharomyces cerevisiae bound to the nucleosome. NuA4 comprises two major modules: the catalytic histone acetyltransferase (HAT) module and the transcription activator-binding TRA module. The nucleosome is mainly bound by .

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