Cryo‐EM Studies of the Translocation Process

Cryo‐electron microscopy studies of ribosomal complexes in various stages of translocation in E. coli and several eukaryotes have resulted in a complex picture of the dynamic process of elongation factor binding and conformational changes. Use of antibiotics, antifungal agents, and nonhydrolyzable GTP analogs (in collaborations with Måns Ehrenberg (Uppsala), Gregers Rom Andersen, Poul Nissen (Aarhus), and Juan‐Pedro Ballesta (Madrid)) results in the trapping of defined states, such that a 3D reconstruction can be built up from thousands of images of ribosomes all in the same conformation. We observe uniformity in the binding position of EF‐G/EF2 and in the conformational responses of the ribosome to the factor binding (ratchet motion, swiveling of L1 stalk, opening/closing of the GTPase‐associated center), reaffirming the view that the basic mechanism of translocation is conserved.