1. Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
2. Department of Biochemistry, Vanderbilt University, Nashville, TN, USA.
3. Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
4. Department of Chemistry, Vanderbilt University, Nashville, TN, USA.
5. Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA.