Mechanistic understanding of the reading and writing of DNA methylation

DNA methylation guides transcription and the formation of heterochromatin, and is commonly dysregulated in a number of diseases. DNA methylation is inextricably linked to the chromatin environment; DNA methyltransferases bind directly to nucleosomes and histone post-translational modifications alter methyltransferase binding and catalysis. Despite the critical role of DNA methylation, few molecular details are available to describe how it is controlled within intact nucleosomes. Biochemical and structural studies to date have used short DNA fragments or linear peptide sequences to infer control mechanisms of DNA methyltransferases. I will build on my expertise and use chemical and catalytic approaches to create site-specifically modified nucleosomes. I will use single-particle cryo-electron microscopy to study individual nucleosome-DNA methylation protein complexes and combine these findings with biochemical and biophysical approaches to help explain how these proteins spatiotemporally deposit and maintain DNA methylation. I aim to investigate the structure of the complete DNA methylation pathway; from the initial recruitment of factors to modified chromatin, to the correct loading and catalysis of DNA methylation sites, to subsequent maintenance of nucleosome bound hemi-methylated DNA. This work will transform our understanding of how DNA methylation is deposited in chromatin and how this can become dysregulated in disease.