1. Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
2. European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, United Kingdom
3. Kavli Institute of Nanoscience Delft (KIND), Department of Bionanoscienes, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
4. Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, Malet Street, London WC1E 7HX, United Kingdom