1. Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
2. Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
3. Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
4. Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA