1. Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
2. Department of Chemistry and Department of Molecular and Cell Biology University of California Berkeley CA 94720 USA
3. Collaborative to Halt Antibiotic-Resistant Microbes, Department of Pediatrics University of California San Diego, La Jolla CA 92093-0760 USA
4. Skaggs School of Pharmacy & Pharmaceutical Sciences University of California San Diego, La Jolla CA 92093-0760 USA
5. Department of Chemistry and Henry Eyring Center for Cell and Genome Sciences University of Utah Salt Lake City UT 84112 USA