1. Molecular Cryo-Electron Microscopy Unit, Okinawa Institute of Science and Technology Graduate University , Onna-son, Okinawa , Japan
2. Department of Biology, Moscow Lomonosov University , Moscow , Russia
3. N.N.Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences , Moscow , Russia
4. Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences , Moscow , Russia
5. Institute of Biological Chemistry, Academia Sinica , Nankang, Taipei , Taiwan