1. RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
2. BIRD, JST, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
3. Division of Structure Biology, Department of Basic Medical Science, Institute of Medical Science, University of Tokyo, 4-6-1 Shiroganedai, Minato-ku, Tokyo 108-8639, Japan
4. CREST, JST, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan