Three-dimensional cryo-electron microscopy localization of EF2 in the Saccharomyces cerevisiae 80S ribosome at 17.5 angstrom resolution

Using a sordarin derivative, an antifungal drug, it was possible to determi ne the structure of a eukaryotic ribosome-EF2 complex at 17.5 Angstrom reso lution by three-dimensional (3D) cryo-electron microscopy. EF2 is directly visible in the 3D map and the overall arrangement of the complex from Sacch aromyces cerevisiae corresponds to that previously seen in Escherichia coli , However, pronounced differences were found in two prominent regions. Firs t, in the yeast system the interaction between the elongation factor and th e stalk region of the large subunit is much more extensive. Secondly, domai n IV of EF2 contains additional mass that appears to interact with the head of the 40S subunit and the region of the main bridge of the 60S subunit, T he shape and position of domain IV of EF2 suggest that it might interact di rectly with P-site-bound tRNA.