Structural Biology and Biocomputing Programme, Spanish National Cancer Research Center (CNIO), Madrid, Spain.|CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.|Institute of Structural and Molecular Biology, University College London, London, United Kingdom.|Structural Biology and Biocomputing Programme, Spanish National Cancer Research Center (CNIO), Madrid, Spain.|CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.|Institute of Structural and Molecular Biology, University College London, London, United Kingdom, Chemistry Department, University College London (UCL), London, United Kingdom.