1. Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninski pr. 59, 117333 Moscow, Russian Federation, A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119899, Moscow, Russian Federation, and Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, Am Klopferspitz 18A, 82152, Martinsried, Germany