1. Department of Informatics Novartis Institutes for BioMedical Research Cambridge MA 02139USA
2. Department of Bacteriology Wisconsin Energy Institute, University of Wisconsin Madison WI 53706USA
3. Department of Microbiology and Immunology and Department of Cell and Tissue Biology University of California, San Francisco San Francisco CA 94158USA
4. Department of Molecular Microbiology John Innes Centre, Norwich Research Park Norwich NR4 7UHUK