1. Department of Chemistry and Molecular Biology, University of Gothenburg, SE-40530 Gothenburg, Sweden;
2. Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
3. RIKEN SPring-8 Center, Hyogo 679-5148, Japan
4. Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
5. Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen, Switzerland