The frozen-hydrated specimens were imaged at −170 °C using a Polara G2 electron microscope (FEI Company) equipped with a field emission gun and a direct detection device (Gatan K2 Summit). The microscope was operated at 300 kV with a magnification of ×15,500, resulting in an effective pixel size of 2.5 Å at the specimen level. We used SerialEM 26 (link) to collect low-dose, single-axis tilt series with dose fractionation mode at about 5 μm defocus and a cumulative dose of ~50 e−/Å2 distributed over 35 stacks. Each stack contains ~8 images. Over 2,000 tilt series were collected from −51° to 51° with increment of 3°. We used Tomoauto 25 (link) to facilitate data processing which includes drift correction of dose-fractionated data using Motioncorr 27 (link) and assembly of corrected sums into tilt series, automatic fiducial seed model generation, alignment and contrast transfer function correction of tilt series by IMOD 28 (link), and reconstruction of tilt series into tomograms by Tomo3D 29 (link). Each tomographic reconstruction is 3,710 × 3,838 × 2,400 pixels and ~130Gb in size. In total, 2,062 tomographic reconstructions from 7 different strains were generated (Supplementary Information Table 2).