[1] Univ London Imperial Coll Sci Technol & Med, Div Invest Sci, Dept Microbiol, Fac Med, London SW7 2AZ, England
[2] Univ London Imperial Coll Sci Technol & Med, Div Mol Biosci, Dept Life Sci, London SW7 2AZ, England
[3] Univ London Imperial Coll Sci Technol & Med, Div Biol, Dept Life Sci, London SW7 2AZ, England
[4] Inst Canc Res, Chester Beatty Labs, Sect Struct Biol, London SW3 6JB, England
[5] Univ Leeds, Astburt Ctr Struct Mol Biol, Leeds LS2 9JT, W Yorkshire, England
[6] Rutgers State Univ, Dept Mol Biol & Biochem, Piscataway, NJ 08854 USA
[7] Rutgers State Univ, Waksman Inst Microbiol, Piscataway, NJ 08854 USA
[8] Russian Acad Sci, Inst Genet Biol, Moscow 123182, Russia