1. Department
of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
2. Department
of Biochemistry, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec H3G1Y6, Canada
3. Department
of Microbiology and Molecular Genetics, School of Medicine, University of Pittsburgh, 450 Technology Drive, Pittsburgh, Pennsylvania 15219-3143, United States
4. Department
of Microbiology and Immunology, McGill University, 3775 University, Montreal, Quebec H3A 2B4, Canada