1. School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30306, United States
2. New York Structural Biology Center, New York, New York 10027, United States
3. Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30306, United States
4. School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30306, United States