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Updated: Jun 17, 2026
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Comparative RNA Structure Analysis of Nascent and Mature Transcripts in Saccharomyces cerevisiae
Published on: February 27, 2026
The final step in 5.8S rRNA processing is cytoplasmic in Saccharomyces cerevisiae
Emma Thomson1, David Tollervey
1Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland, UK.
Molecular and Cellular Biology
|December 17, 2009
Summary
Yeast cytoplasmic 60S ribosome maturation involves a 3'-extended 5.8S rRNA precursor. This precursor is exported from the nucleus and processed by cytoplasmic factors, revealing a new step in ribosome biogenesis.
Area of Science:
- Molecular Biology
- Cell Biology
- Yeast Genetics
Background:
- Ribosome biogenesis is a complex process involving coordinated transcription, processing, and assembly of ribosomal RNA (rRNA) and proteins.
- In yeast (Saccharomyces cerevisiae), the 40S and 60S ribosomal subunits are assembled separately in the nucleus before export to the cytoplasm.
- The maturation of 5.8S rRNA within the 60S subunit precursor was thought to be completed in the nucleus before export.
Purpose of the Study:
- To investigate the processing and maturation of 5.8S rRNA in yeast 60S ribosomal subunits.
- To identify the factors and pathways involved in the cytoplasmic processing of 5.8S rRNA.
- To elucidate the role of nuclear export in the final maturation steps of the 60S subunit.
Main Methods:
- In situ hybridization to detect rRNA forms in yeast cells.
- Leptomycin B (LMB) treatment to inhibit Crm1-dependent nuclear export.
- Coprecipitation assays to identify interacting proteins.
- Analysis of pre-rRNA processing in knockout strains lacking specific nucleases (Rrp6, Ngl2).
Main Results:
- 3 zost'-extended forms of 5.8S rRNA (5.8S+30 pre-rRNA) were detected in the cytoplasm.
- Nuclear export of pre-60S subunits, mediated by Crm1, is required for the presence of these extended forms.
- Nuclear processing of 6S pre-rRNA to 5.8S rRNA is dependent on Rrp6, while cytoplasmic processing of 6S to 5.8S requires Ngl2.
- Pre-60S particles containing 6S pre-rRNA bind Nmd3 and Crm1 for export.
Conclusions:
- Nuclear pre-60S particles are exported to the cytoplasm containing a 3 zost'-extended 5.8S rRNA precursor (6S pre-rRNA).
- Final maturation of 5.8S rRNA from the 6S precursor occurs in the cytoplasm, mediated by the exonuclease Ngl2.
- This study reveals a novel cytoplasmic processing step essential for yeast 60S ribosome biogenesis, challenging previous models of rRNA maturation occurring solely in the nucleus prior to export.
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