Stepwise and dynamic assembly of the earliest precursors of small ribosomal subunits in yeast

Liman Zhang, Chen Wu, Gaihong Cai, She Chen, Keqiong Ye

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


The eukaryotic ribosomal RNA (rRNA) is associated cotranscriptionally with numerous factors into an enormous 90S preribosomal particle that conducts early processing of small ribosomal subunits. The assembly pathway and structure of the 90S particle is poorly understood. Here, we affinity-purified and analyzed the constituents of yeast 90S particles that were assembled on a series of plasmid-encoded 3′-truncated pre-18S RNAs. We determined the assembly point of 65 proteins and the U3, U14, and snR30 small nucleolar RNAs (snoRNAs), revealing a stepwise and dynamic assembly map. The 5′ external transcribed spacer (ETS) alone can nucleate a large complex. When the 18S rRNA is nearly complete, the 90S structure undergoes a dramatic reorganization, releasing U14, snR30, and 14 protein factors that bind earlier. We also identified a reference state of 90S that is fully assembled yet has not undergone 5′ETS processing. The assembly map present here provides a new framework to understand small subunit biogenesis.

Original languageEnglish (US)
Pages (from-to)718-732
Number of pages15
JournalGenes and Development
Issue number6
StatePublished - Mar 15 2016
Externally publishedYes


  • 90S preribosome
  • Mass spectrometry
  • Ribosome assembly
  • Small nucleolar RNA

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology


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