The structure and mechanism of action of Snf2 family proteins.


All eukaryotes encode a series of proteins related to the yeast Snf2 protein by a series of sequences with homology to superfamily II group helicases.  It is thought that this helicase related region uses energy derived from hydrolysis of ATP to translocate along DNA. An issue that remains poorly understood is how the mechanical action of this motor domain is applied to nucleosomes in order to alter their configuration (Narlikar et al., 2013). We are applying a combination of structural approaches including single particle cryo-EM to study how these enzymes interact with nucleosomes.



Even relatively simple eukaryotes such as the budding yeast make over 20 different forms of Snf2 family protein. Many of these proteins are associated with other proteins to form large multisubunit complexes.

Confused? – go to our description for non-scientists - Molecular Motors



The role of human SWI/SNF complexes in cancer


Large scale tumour genome sequencing has revealed that subunits of the human SWI/SNF related chromatin remodelling complexes are mutated at a frequency of 20% across all cancers (Kadoch and Crabtree, 2015). Even more mystifying, specific subunits are mutated in tumours of different tissues. To understand how this complex is altered following subunit loss in cancer we are engineering cell lines to study how subunit loss affects function in different cell types. Changes in the protein composition and genome wide distribution of the complexes will be characterised using the excellent in house facilities. In parallel we will collaborate with clinicians to identify changes that relate to tumour progression in patient material. We will also build the complex and its submodules from recombinant expressed proteins to study its biochemical properties and structure using techniques such as single particle cryo-electron microscopy. This line of work also presents the opportunity to assess the potential for chemical inhibition of the complex and this is ongoing with the Drug Discovery Unit in Dundee.

In combination, the application of these approaches will describe how the action of these complexes is subverted in cancer. Ultimately this will improve detection and treatment of cancers that are driven by alterations to this complex.  



Mechanisms and functions of ATP-dependent chromatin-remodeling enzymes, Narlikar, G.J., Sundaramoorthy, R., and Owen-Hughes, T. (2013). Cell  154, 490-503, doi 10.1016/j.cell.2013.07.011PMCID 3781322

Mammalian SWI/SNF chromatin remodeling complexes and cancer: Mechanistic insights gained from human genomics, Kadoch, C., and Crabtree, G.R. (2015). Science advances  1, e1500447, doi 10.1126/sciadv.1500447PMCID 4640607