Architecture of the yeast small subunit processome

Science. 2017 Jan 13;355(6321):eaal1880. doi: 10.1126/science.aal1880. Epub 2016 Dec 15.


The small subunit (SSU) processome, a large ribonucleoprotein particle, organizes the assembly of the eukaryotic small ribosomal subunit by coordinating the folding, cleavage, and modification of nascent pre-ribosomal RNA (rRNA). Here, we present the cryo-electron microscopy structure of the yeast SSU processome at 5.1-angstrom resolution. The structure reveals how large ribosome biogenesis complexes assist the 5' external transcribed spacer and U3 small nucleolar RNA in providing an intertwined RNA-protein assembly platform for the separate maturation of 18S rRNA domains. The strategic placement of a molecular motor at the center of the particle further suggests a mechanism for mediating conformational changes within this giant particle. This study provides a structural framework for a mechanistic understanding of eukaryotic ribosome assembly in the model organism Saccharomyces cerevisiae.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cryoelectron Microscopy
  • Nucleic Acid Conformation
  • Protein Conformation, beta-Strand
  • RNA, Fungal / chemistry
  • RNA, Fungal / ultrastructure
  • RNA, Ribosomal / chemistry
  • RNA, Ribosomal / ultrastructure
  • RNA, Ribosomal, 18S / chemistry
  • RNA, Ribosomal, 18S / ultrastructure
  • RNA, Small Nucleolar / chemistry
  • RNA, Small Nucleolar / ultrastructure
  • Ribosome Subunits, Small, Eukaryotic / chemistry*
  • Ribosome Subunits, Small, Eukaryotic / ultrastructure*
  • Saccharomyces cerevisiae / chemistry*
  • Saccharomyces cerevisiae / ultrastructure*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / ultrastructure


  • RNA, Fungal
  • RNA, Ribosomal
  • RNA, Ribosomal, 18S
  • RNA, Small Nucleolar
  • RNA, U3 small nucleolar
  • Saccharomyces cerevisiae Proteins