All eukaryotic DNA is organised into chromatin, which must be maintained and regulated to ensure proper gene expression. The density of chromatin plays an important role in gene regulation, with the architecture of chromatin being regulated through chromatin remodellers. While some of the mechanisms of chromatin remodelling enzymes have been characterised, our understanding of these mechanisms is incomplete, especially considering that it is not known how these enzymes are recruited to their targets. To improve our understanding of chromatin remodelling enzymes, our research is focused on CHD4, the most prolific and only essential chromatin remodeler from the CHD family.
To begin to investigate how CHD4 may be recruited and regulated, we have begun to probe its interactions with its binding partners, particularly the BET proteins. The BET family of proteins is comprised of four proteins characterised by tandem bromodomains, canonically considered to be readers of lysine acetylation and an extra-terminal protein interaction domain. The goal of this project was to characterise the interaction between CHD4 and BET proteins by attempting to determine the structure of CHD4 and the BET protein BRD4 bound to a nucleosome using cryo-electron microscopy. Here, we describe the progress towards obtaining this structure, including some preliminary low-resolution reconstructions.