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.

• PMID: 27980088
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Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Chaker-Margot M, Barandun J, Hunziker M, Klinge S

Primary Lit For

SNR17B | SNR17A | Small ribosomal subunit processome | UTP-A complex | UTP-B complex | MPP10 complex

Additional Lit For

Review For