1. Department of Biophysics, The University of Texas Southwestern Medical Center, Dallas, TX 75390
2. Department of Biology, Chemistry, & Physical Sciences, APS/Illinois Institute of Technology, Argonne, IL 60439
3. Department of Molecular Biology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
4. Baylor College of Medicine, Houston, TX 77030
5. Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390