1. Department of Chemistry, University of Wisconsin—Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
2. Division of Chemistry and Chemical Engineering, California Institute of Technology, 210-41, 1200 East California Boulevard, Pasadena, California 91125, United States
3. Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, Zurich 8093, Switzerland