3-DIMENSIONAL RECONSTRUCTION WITH CONTRAST TRANSFER-FUNCTION CORRECTION FROM ENERGY-FILTERED CRYOELECTRON MICROGRAPHS - PROCEDURE AND APPLICATION TO THE 70S ESCHERICHIA-COLI RIBOSOME

Cryoelectron microscopy provides the means of studying macromolecules in their native state. However, the contrast transfer function (CTF) m akes the images and the three-dimensional (3D) maps derived from them difficult to interpret. We developed methods to determine the CTF from experimental data and to obtain a CTF-corrected 3D reconstruction. Th e CTF correction and 3D reconstruction accomplished in one step make i t easy to combine different defocus data sets and decrease the error a ccumulation in the computation. These methods were applied to energy-f iltered images of the 70S Escherichia coli ribosome, resulting in a di stortion-free 3D map of the ribosome at 1/24.5 Angstrom(-1) resolution , as determined by the differential phase residual resolution criterio n. (C) 1997 Academic Press.