1. Life Science Group, National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinch 30076, Taiwan
2. Chemistry and Biochemistry Department, The University of Texas at Austin, Austin, Texas 78712
3. Centre of Advanced Study in Crystallography and Biophysics, University of Madras, Guindy Campus, Chennai 600 025, India
4. RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
5. Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
6. RIKEN Systems and Structural Biology Center, Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan
7. Graduate School of Science, the University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
8. Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996
9. Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831.