1. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 04109, United States
3. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
4. Howard Hughes Medical Institute, Cambridge, Massachusetts 02139, United States
5. Bio-inspired Solar Energy Program, Canadian Institute for Advanced Research, Toronto, ON M5G 1M1, Canada