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Updated: Jul 26, 2026
02:54
A Rapid Technique for the Visualization of Live Immobilized Yeast Cells
Published on: November 9, 2006
Yeast heterochromatin is a dynamic structure that requires silencers continuously
1Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854 USA.
Genes & Development
|February 26, 2000
Summary
Yeast silencers are continuously required to maintain transcriptional silencing. Silencing factors can dynamically associate with and stabilize silent chromatin outside of S phase, indicating dynamic heterochromatin.
Area of Science:
- Molecular Biology
- Epigenetics
- Yeast Genetics
Background:
- Transcriptional silencing at the HM loci in yeast relies on cis-acting silencers active during S-phase.
- Understanding the role of regulatory elements in maintaining repression is crucial for comprehending heterochromatin stability.
Purpose of the Study:
- To investigate the continuous requirement of silencers for maintaining transcriptional repression.
- To determine if silent chromatin can be stabilized by silencing factors outside of S phase.
Main Methods:
- Utilized site-specific recombination to excise preassembled silent chromatin fragments from silencers.
- Assessed the stability of DNA rings derived from HMR and HML loci.
- Employed overexpression of silencing proteins (Sir3p, Sir4p) and chromatin immunoprecipitation (ChIP) assays.
Main Results:
- DNA rings lacking silencers were initially silent but reactivated, demonstrating a continuous need for silencers.
- HML-derived rings with a protosilencing element remained stably repressed.
- Overexpression of Sir3p and Sir4p blocked reactivation, and Sir3p incorporation into silent chromatin occurred even in G(1)-arrested cells.
Conclusions:
- Silencers (or protosilencers) are essential for the continuous maintenance of silent chromatin.
- Yeast heterochromatin is dynamic, as silencing factors can associate with and stabilize preassembled silent chromatin outside of S phase.
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