1 Merkin Institute of Transformative Technologies in Health Care, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
2 Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
3 Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
4 Merkin Institute of Transformative Technologies in Health Care, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA. drliu@fas.harvard.edu.
5 Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA. drliu@fas.harvard.edu.
6 Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA. drliu@fas.harvard.edu.