1. Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
2. Pharmaceutical Sciences, University of Illinois Chicago, Chicago, IL 60612, USA
3. Biomolecular Cryo-Electron Microscopy Facility, University of California-Santa Cruz, Santa Cruz, CA 95064, USA
4. Laboratório de Ciências Físicas, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro 28013-602, Brazil
5. Department of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
6. Department of Chemistry and Biochemistry, University of California-Santa Cruz, Santa Cruz, CA 95064, USA