Experimental phase determination with selenomethionine or mercury-derivatization in serial femtosecond crystallography

• Main Authors: Keitaro Yamashita, Naoyuki Kuwabara, Takanori Nakane, Tomohiro Murai, Eiichi Mizohata, Michihiro Sugahara, Dongqing Pan, Tetsuya Masuda, Mamoru Suzuki, Tomomi Sato, Atsushi Kodan, Tomohiro Yamaguchi, Eriko Nango, Tomoyuki Tanaka, Kensuke Tono, Yasumasa Joti, Takashi Kameshima, Takaki Hatsui, Makina Yabashi, Hiroshi Manya, Tamao Endo, Ryuichi Kato, Toshiya Senda, Hiroaki Kato, So Iwata, Hideo Ago, Masaki Yamamoto, Fumiaki Yumoto, Toru Nakatsu
• Format: Article
• Language: English
• Published: International Union of Crystallography 2017-09-01
• Series: IUCrJ
• Subjects: serial femtosecond crystallography; SAD phasing; XFELs; selenomethionine derivatization; mercury soaking
• Online Access: http://scripts.iucr.org/cgi-bin/paper?S2052252517008557

Serial femtosecond crystallography (SFX) using X-ray free-electron lasers (XFELs) holds enormous potential for the structure determination of proteins for which it is difficult to produce large and high-quality crystals. SFX has been applied to various systems, but rarely to proteins that have previously unknown structures. Consequently, the majority of previously obtained SFX structures have been solved by the molecular replacement method. To facilitate protein structure determination by SFX, it is essential to establish phasing methods that work efficiently for SFX. Here, selenomethionine derivatization and mercury soaking have been investigated for SFX experiments using the high-energy XFEL at the SPring-8 Angstrom Compact Free-Electron Laser (SACLA), Hyogo, Japan. Three successful cases are reported of single-wavelength anomalous diffraction (SAD) phasing using X-rays of less than 1 Å wavelength with reasonable numbers of diffraction patterns (13 000, 60 000 and 11 000). It is demonstrated that the combination of high-energy X-rays from an XFEL and commonly used heavy-atom incorporation techniques will enable routine de novo structural determination of biomacromolecules.