1. Howard Hughes Medical Institute, Department
of Molecular Biology and Center for Computational and Integrative
Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
2. Department
of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, United States
3. Department
of Chemistry and Chemical Biology, Harvard University, 12 Oxford
Street, Cambridge, Massachusetts 02138, United States
4. School of Life Sciences, Tsinghua University, Beijing 100084, China