2.3. Data collection and processing  

Data were obtained using an ADSC Q315r detector (Area Detector Systems Corporation, USA) on BL17U1 at Shanghai Synchrotron Radiation Facility (SSRF). Since the crystallization condition contained cryoprotectants, the crystal was flash-cooled in liquid nitrogen and directly mounted for X-ray diffraction. The diffraction data were collected at 100 K and were processed with iMosflm (Battye et al., 2011 ▸). The crystal diffracted to 1.7 Å resolution and belonged to the tetragonal space group P4₁2₁2, as checked with POINTLESS (Evans, 2011 ▸), with unit-cell parameters a = b = 72.73, c = 171.31 Å. A total of 331 630 reflections were integrated to a resolution of 1.70 Å and were merged to obtain 51 175 unique reflections with an overall R _meas of 0.090 and a completeness of 99.04%. Data-collection statistics are summarized in Table 3 ▸.

Values in parentheses are for the outer shell.