1. Department of Chemistry, University of California, Berkeley, California 94720, United States
2. Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria
3. Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukus, Okinawa 903-0213, Japan
4. Department of Molecular and Cell Biology and the California Institute for Qualitative Biosciences, University of California, Berkeley, CA 94720, United States