1. The Francis Crick Institute, London, NW1 1AT, United Kingdom
2. London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom
3. Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom
4. Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, Malet Street, London, WC1E 7HX, United Kingdom