1. Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
2. The Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, 1311 Cumberland Avenue, Knoxville, Tennessee 37916, United States
3. National Science Foundation, 2415 Eisenhower Avenue, Alexandria, Virginia 22314, United States
4. Department of Structural Biology, St. Jude Children’s Research Hospital, 262 Danny Thomas Pl, Memphis, Tennessee 38105, United States