1. Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
2. Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA.
3. Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA.
4. The Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
5. Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544, USA.