Structure of the chromatin remodelling enzyme Chd1 bound to a ubiquitinylated nucleosome

Ramasubramanian Sundaramoorthy; Amanda L. Hughes; Hassane El-Mkami; David Norman; Tom Owen-Hughes

We previously showed that Chd1 binding results in nucleotide-dependent unwrapping of nucleosomal DNA resulting from the interaction of the DNABD with linker DNA (Sundaramoorthy et al., 2017) . The higher resolution of the current structure shows that precisely two turns of nucleosomal DNA are . CC-BY-NC 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/290874 doi: bioRxiv preprint unravelled ( Figure 1 ). The extent of DNA unwrapping observed here when Chd1 is bound to nucleosomes flanked by a 14 base pair linker DNA is identical to that observed when Chd1 is bound to the opposite surface of the 601 nucleosome positioning sequence with a 63 base pair linker (Farnung et al., 2017) . As the interaction of histones with the two sides of the 601 positioning sequence differ quite dramatically (Chua et al., 2012; Hall et al., 2009; Levendosky et al., 2016; Ngo et al., 2015) , this suggests that the extent of unwrapping is dominated by the properties of Chd1 rather than the affinity of DNA for the octamer. The path of this unwrapped DNA is oriented away from the plane of the wrapped DNA gyre and is kinked at the location where contacts are made with the SANT-SLIDE domains ( Figure 1 ). Other than DNA unwrapping we do not detect additional changes in the organisation of DNA on Chd1 bound nucleosomes at this resolution.