Cryo-EM structure of yeast 90S preribosome at 3.4 Angstrom resolution

Abstract

Previously, we determined a cryo-EM structure of Saccharomyces cerevisiae 90S preribosome obtained after depletion of the RNA helicase Mtr4 at 4.5 [A] resolution (Sun et al., 2017). The 90S preribosome is an early assembly intermediate of small ribosomal subunit. Here, the structure was improved to 3.4 [A] resolution and reveals many previously unresolved structures and interactions, in particular around the central domain of 18S rRNA. The central domain adopts a closed conformation in our structure, in contrast to an open conformation in another high-resolution structure of S. cerevisiae 90S. The new model of 90S would serve as a better reference for investigation of the assembly mechanism of small ribosomal subunit.