1. Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States
2. Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
3. Department of Integrative Computational and Structural Biology, The Scripps Research Institute, La Jolla, United States
4. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, United States
5. Department of Biochemistry and Molecular Biology, The University of Texas-Houston Medical School, Houston, United States