Investigating how chromatin guides de novo DNA methylation

DNA methylation is the most common epigenetic mark found in mammals and is associated with gene repression. It is catalysed by DNA methyltransferases (DNMTs) and dysregulation can cause developmental diseases and cancers. 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.

Our objective will be to help explain how DNA methylation is deposited and maintained in mammals. Focusing on maintenance DNA methyltransferase DNMT1, this project will reconstitute modified chromatin-DNA methylation maintenance complexes and investigate their structure and activity using a wide variety of techniques, principally cryogenic Electron Microscopy (cryo-EM). Ultimately, we will validate our findings investigating recruitment and activity using tailored mutants in cells. This project will help explain:

·        How DNA methyltransferase DNMT1 ensures correct maintenance of DNA methylation after DNA replication, in a chromatin context.

·        How post-translational marks on chromatin help guide DNA methylation maintenance and how multiple marks on histone and DNA integrated to ensure correct catalysis.

·        How individual domains and disease associated variants of DNMT1 effect DNA methylation maintenance.

·        If our structures can be used to help guide structure-based drug design approaches, targeting active conformations found while engaged with modified nucleosome substrate.

This would be an ideal project to suit a passionate, motivated student interested in how molecular understanding can help explain fundamental biological processes.