1. Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
2. Howard Hughes Medical Institute, University of California at Los Angeles, and U.S. Department of Energy (UCLA-DOE) Institute for Genomics and Proteomics, Los Angeles, CA 90095, USA.
3. Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
4. Department of Medicinal Chemistry, University of Washington, Seattle, WA 98177, USA.
5. Department of Biochemistry and Structural Biology, Lund University, SE-221 00 Lund, Sweden.
6. Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA.
7. UCLA-DOE Institute for Genomics and Proteomics, Los Angeles, CA 90095, USA.
8. Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.