1. Boyce Thompson Institute and Department of Chemistry and Chemical Biology Cornell University Ithaca NY USA
2. Present Address: Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena CA USA
3. Departments of Bacteriology Medical Microbiology and Immunology University of Wisconsin-Madison Madison WI USA
4. Department of Pharmaceutical Microbiology Hans-Knöll-Institute Friedrich Schiller University Jena Germany