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Isolation of Cognate RNA-protein Complexes from Cells Using Oligonucleotide-directed Elution
Published on: January 16, 2017
Condensin regulates rDNA silencing by modulating nucleolar Sir2p
Felix Machín1, Konstantinos Paschos, Adam Jarmuz
1Cell Cycle Group, Medical Research Council Clinical Sciences Centre, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
Current Biology : CB
|January 24, 2004
Summary
Yeast condensin organizes ribosomal DNA (rDNA) chromatin structure, which is essential for regulating gene silencing and maintaining cellular lifespan. This organization ensures proper localization of silencing proteins, preventing recombination and controlling lifespan.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Ribosomal DNA (rDNA) in Saccharomyces cerevisiae exhibits transcriptional silencing of RNA polymerase II genes.
- This silencing is mediated by SIR2 and linked to suppressed rDNA recombination and cellular lifespan control.
- rDNA silencing occurs despite high RNA polymerase I transcription rates, suggesting unique mechanisms compared to other silencing pathways.
Purpose of the Study:
- To investigate the role of yeast condensin in organizing rDNA chromatin structure.
- To determine if condensin's function in rDNA topology is crucial for maintaining silencing protein balance.
- To elucidate the involvement of condensin in establishing heterochromatin-like structures within rDNA repeats.
Main Methods:
- Chromatin immunoprecipitation (ChIP) to analyze protein localization and histone modifications.
- Microscopy techniques to visualize the spatial organization of silencing proteins.
- Genetic analysis of condensin mutants in Saccharomyces cerevisiae.
Main Results:
- Yeast condensin organizes the specialized topology of rDNA chromatin.
- Condensin is necessary for maintaining the correct balance of telomeric and nucleolar Sir2p.
- Condensin mutants exhibit relocalization of telomeric Sir2p to rDNA and histone hyperacetylation at telomeres.
- Data reveal condensin's role in arranging rDNA repeats into heterochromatin-like structures.
Conclusions:
- Yeast condensin plays a critical role in structuring rDNA heterochromatin.
- This structural organization by condensin is vital for delineating silencing domains within the nucleus.
- Condensin's function impacts rDNA stability, gene silencing, and potentially cellular lifespan.
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