Visualizing the protein synthesis machinery: New focus on the translational GTPase elongation factor Tu

Abstract

Three-dimensional cryoelectron microscopy (cryo-EM) is one of the few techniques capable of visualizing large, dynamic molecules. The ribosome, a molecular machine that synthesizes proteins in the cell, provides many examples of such dynamic assemblages, and the complex between the bacterial ribosome and translation elongation factor Tu (EF-Tu), stabilized by the antibiotic kirromycin, was the first to be visualized by cryo-EM (1). Since that time, the technique has progressed enormously. In this issue of PNAS, Joachim Frank and colleagues report the structure of the ribosome·EF-Tu·tRNA complex at a resolution of 6.7 A (2), which presents a substantial advancement over previously reported cryo-EM reconstructions of that complex and provides new insights into its molecular architecture.