1. Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
2. Department of Microbiology
3. Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
4. Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210
5. Department of Chemistry
6. Department of Molecular and Cell Biology, University of California, Berkeley, California 94720