Figure 6. Model for RSC1 and RSC2 action on wrapped versus partially-unwrapped nucleosomes.

Here, flexible/positioning DNA sequences and the protein Hmo1 promote wrapping (Anderson et al., 2002; Iyer, 2012; Panday and Grove, 2017). In contrast, partial unwrapping can be facilitated by ‘stiff’ (AT-rich) DNA sequences, acetylation (e.g., H3 K56ac), the binding of general regulatory transcription factors (not shown) to entry/exit DNA, or by mutation of residues within/near the H3 αN helix (which normally binds entry/exit DNA) (Segal and Widom, 2009; Neumann et al., 2009; Knight et al., 2014; Ferreira et al., 2007). Whereas fully-wrapped nucleosomes are remodeled well by RSC1 or RSC2 complexes, partially-unwrapped nucleosomes are better managed and remodeled by RSC1 complexes.