1. Section of Microbiology and MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
2. Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
3. Institute of Molecular Genetics, Russian Academy of Sciences, Moscow 123182, Russia
4. Waksman Institute for Microbiology and Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA