The Mixed Lineage Leukemia (MLL) complex plays a key role in gene regulation by covalently modifying the nucleosome packaging unit of DNA. However, we do not understand how the MLL enzyme works on its nucleosome substrate. I am working to determine the structure of the 500 kDa MLL/nucleosome complex by X-ray crystallography to provide insight into its molecular mechanism and the basis for its association with leukemia