Devitrification reduces beam-induced movement in cryo-EM.

ABSTRACT: As cryo-EM approaches the physical resolution limits imposed by electron optics and radiation damage, it becomes increasingly urgent to address the issues that impede high-resolution structure determination of biological specimens. One of the persistent problems has been beam-induced movement, which occurs when the specimen is irradiated with high-energy electrons. Beam-induced movement results in image blurring and loss of high-resolution information. It is particularly severe for biological samples in unsupported thin films of vitreous water. By controlled devitrification of conventionally plunge-frozen samples, the suspended film of vitrified water was converted into cubic ice, a polycrystalline, mechanically stable solid. It is shown that compared with vitrified samples, devitrification reduces beam-induced movement in the first 5?e?Å^-2 of an exposure by a factor of ?4, substantially enhancing the contribution of the initial, minimally damaged frames to a structure. A 3D apoferritin map reconstructed from the first frames of 20?000 particle images of devitrified samples resolved undamaged side chains. Devitrification of frozen-hydrated specimens helps to overcome beam-induced specimen motion in single-particle cryo-EM, as a further step towards realizing the full potential of cryo-EM for high-resolution structure determination.

SUBMITTER: Wieferig JP 

PROVIDER: S-EPMC7924229 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature