1. Department of Molecular Biophysics and Biochemistry (MB&B), Howard Hughes Medical Institute (HHMI), Yale University School of Medicine, Boyer Center for Molecular Medicine, 295 Congress Avenue, New Haven, CT 06536–9812, USA.
2. Department of MB&B, Yale University, Bass Center for Molecular and Structural Biology, 266 Whitney Avenue, New Haven, CT 06520–8114, USA.
3. Department of Chemistry, Yale University, New Haven, CT 06520–8107, USA.
4. HHMI, Yale University, Bass Center for Molecular and Structural Biology, 266 Whitney Avenue, New Haven, CT 06520–8114, USA.