1. School of Life Science and Technology, Tokyo Institute of Technology, Nagatsuta-cho 4259, Midori-ku, Yokohama 226-8501, Japan
2. SR Life Science Instrumentation Unit, RIKEN/SPring-8 Center, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
3. MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
4. International Research Frontiers Initiative (IRFI), Tokyo Institute of Technology, Nagatsuta-cho 4259, Midori-ku, Yokohama 226-8501, Japan