1. Department of Biochemistry and Molecular Biology, College of Medicine, Center for Structural Biology, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
2. The BIO5 Institute, Keating Building, University of Arizona, Tucson, AZ 85721, USA
3. Institute of Biotechnology, Helsinki Institute of Life Science HiLIFE, University of Helsinki, 00014 Helsinki, Finland
4. Molecular Microbiology Group, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UK