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Mediator dynamics during heat shock in budding yeast.
Debasish Sarkar1, Z Iris Zhu2, Elizabeth R Knoll1,3
1Wadsworth Center, New York State Department of Health, Albany, New York 12208, USA.
Genome Research
|November 17, 2021
Summary
Mediator complex association with promoters becomes more stable in yeast under heat shock conditions. This complex remains bound even at repressed genes, suggesting altered transcription regulation.
Area of Science:
- Molecular Biology
- Gene Regulation
- Eukaryotic Transcription
Background:
- The Mediator complex is crucial for RNA polymerase II (Pol II) transcription in eukaryotes.
- In yeast, Mediator facilitates preinitiation complex (PIC) assembly but only transiently before Pol II escape.
- Kin28 inhibition stabilizes Mediator association, but genome-wide dynamics under stress are unknown.
Purpose of the Study:
- To investigate Mediator complex occupancy and dynamics genome-wide in yeast under heat shock or CdCl2 exposure.
- To examine the role of Kin28 in Mediator association under these stress conditions.
- To understand Mediator's behavior at both activated and repressed genes during stress.
Main Methods:
- Genome-wide analysis of Mediator and Pol II occupancy using ChIP-seq.
- Depletion of Kin28 and generation of yeast strains lacking Hmo1 (hmo1Δ).
- Exposure of yeast to heat shock or CdCl2 stress conditions.
Main Results:
- Pol II occupancy depends on Mediator similarly under normal and heat shock conditions.
- Mediator association increases with Kin28 depletion under normal growth but shows little increase upon heat shock, indicating greater stability.
- Mediator remains associated upstream of core promoters at repressed genes, irrespective of Kin28 levels, with strongest association at Hmo1-bound promoters.
Conclusions:
- Heat shock leads to a more stable Mediator association with yeast promoters compared to Kin28 depletion.
- Mediator can be recruited by activators but fail to engage PICs at stress-repressed genes.
- Hmo1 influences Mediator's persistent association at repressed promoters.
- Heat shock alters Mediator's dependence on PIC components, suggesting stronger activator engagement or altered dynamics.
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