1. Structural Biology Unit, CIC-bioGUNE, Derio, Basque Country; Spain
2. Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign; Urbana IL USA
3. Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign; Urbana IL USA
4. MOE Key Laboratory of Bioinformatics, Center for Structural Biology, School of Life Sciences, Tsinghua University; Beijing China
5. Department of Molecular Biology and Genetics, HHMI, Johns Hopkins University School of Medicine; Baltimore MD USA
6. Department of Physics, University of Illinois at Urbana-Champaign; Urbana IL USA
7. Department of Biochemistry and Molecular Biophysics, HHMI, Columbia University; New York NY USA
8. Department of Biological Sciences, Columbia University; New York NY USA