SWI/SNF-family chromatin remodeling complexes, such as S. cerevisiae RSC, slide and eject nucleosomes to regulate transcription. Within nucleosomes, stiff DNA sequences confer spontaneous partial unwrapping, prompting whether and how SWI/SNF-family remodelers are specialized to remodel partially-unwrapped nucleosomes. RSC1 and RSC2 are orthologs of mammalian PBRM1 (polybromo) which define two separate RSC sub-complexes. Remarkably, in vitro the Rsc1-containing complex remodels partially-unwrapped nucleosomes much better than does the Rsc2-containing complex. Moreover, a rsc1Δ mutation, but not rsc2Δ, is lethal with histone mutations that confer partial unwrapping. Rsc1/2 isoforms both cooperate with the DNA-binding proteins Rsc3/30 and the HMG protein, Hmo1, to remodel partially-unwrapped nucleosomes, but show differential reliance on these factors. Notably, genetic impairment of these factors strongly reduces the expression of genes with wide nucleosome-deficient regions (e.g. ribosomal protein genes), known to harbor partially-unwrapped nucleosomes. Taken together, Rsc1/2 isoforms are specialized through composition and interactions to manage and remodel partially-unwrapped nucleosomes.
Data Availability: Sequencing data has been deposited at NCBI under SRA accession #PRJNA573112. Source data files have been provided for Figures 3, 4, and 5.
Specialization of the Chromatin Remodeler RSC to Mobilize Partially-Unwrapped NucleosomesNCBI SRA, PRJNA573112.
- Alisha Schlichter
- Margaret M Kasten
- Bradley R Cairns
- Timothy J Parnell
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Stephen Buratowski, Harvard Medical School, United States
© 2020, Schlichter et al.
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