1. Department of Chemistry, Brandeis University, Waltham, Massachusetts 02454, United States
2. Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne, Illinois 60439, United States
3. Center for Structural Genomics of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, Illinois 60637, United States
4. Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, United States
5. Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60557, United States
6. Department of Biology, Brandeis University, Waltham, Massachusetts 02454, United States