1. Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, Bass Building, New Haven, CT 06511, USA.
2. Interdepartmental Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06511, USA.
3. Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA.
4. Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.