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A late-acting quality control process for mature eukaryotic rRNAs
Frederick J LaRiviere1, Sarah E Cole, Daniel J Ferullo
1Howard Hughes Medical Institute, Brandeis University, Waltham, Massachusetts 02454, USA.
Molecular Cell
|December 26, 2006
Summary
Eukaryotes possess a quality control mechanism that downregulates nonfunctional ribosomal RNAs (rRNAs). This process, termed nonfunctional rRNA decay (NRD), targets and eliminates mutated rRNAs within mature ribosomes, ensuring cellular integrity.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Ribosome biogenesis is a complex process essential for protein synthesis.
- Ensuring the structural and functional integrity of ribosomes requires stringent quality control.
- Defective ribosomal components can compromise cellular function.
Purpose of the Study:
- To investigate the quality control mechanisms governing ribosome biogenesis in eukaryotes.
- To identify how the cell detects and eliminates nonfunctional ribosomal RNAs (rRNAs).
- To characterize the nonfunctional rRNA decay (NRD) pathway in Saccharomyces cerevisiae.
Main Methods:
- Introduction of specific point mutations into Saccharomyces cerevisiae rRNA genes.
- Analysis of mature rRNA levels in wild-type and mutant strains.
- Assessment of rRNA stability in assembled ribosomes and ribosomal subunits.
Main Results:
- Point mutations in critical rRNA regions (25S peptidyl transferase center, 18S decoding site) led to significant rRNA downregulation.
- Downregulation occurred through decreased stability of mature rRNA within functional ribosomes and subunits.
- The nonfunctional rRNA decay (NRD) pathway was identified as the mechanism responsible for eliminating defective rRNA.
Conclusions:
- Eukaryotes possess a robust quality control system, nonfunctional rRNA decay (NRD), to maintain ribosome integrity.
- NRD actively detects and eliminates ribosomes containing nonfunctional rRNA components.
- This mechanism is crucial for ensuring the fidelity of protein synthesis by preventing the propagation of defective ribosomes.
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