1. Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
2. Fels Institute for Cancer Research and Molecular Biology, Temple University, Philadelphia, PA 19140, USA.
3. Department of Microbiology and Immunology, Temple University, Philadelphia, PA 19140, USA.
4. Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
5. Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA.