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Updated: Jun 11, 2026
Generation and Purification of Human INO80 Chromatin Remodeling Complexes and Subcomplexes
Published on: October 23, 2014
A chromatin-remodeling protein is a component of fission yeast mediator
Olga Khorosjutina1, Paulina H Wanrooij, Julian Walfridsson
1From the Division of Metabolic Diseases, Karolinska Institutet, SE-141 86 Stockholm, Sweden.
Abstract:
The multiprotein Mediator complex is an important regulator of RNA polymerase II-dependent genes in eukaryotic cells. In contrast to the situation in many other eukaryotes, the conserved Med15 protein is not a stable component of Mediator isolated from fission yeast. We here demonstrate that Med15 exists in a protein complex together with Hrp1, a CHD1 ATP-dependent chromatin-remodeling protein. The Med15-Hrp1 subcomplex is not a component of the core Mediator complex but can interact with the L-Mediator conformation. Deletion of med15(+) and hrp1(+) causes very similar effects on global steady-state levels of mRNA, and genome-wide analyses demonstrate that Med15 associates with a distinct subset of Hrp1-bound gene promoters. Our findings therefore indicate that Mediator may directly influence histone density at regulated promoters.
Insights
The fission yeast Med15 protein forms a complex with chromatin remodeler Hrp1, influencing mRNA levels. This Med15-Hrp1 complex interacts with Mediator, suggesting a role in regulating gene transcription and histone density.
Area of Science:
- Molecular Biology
- Gene Regulation
- Chromatin Dynamics
Background:
- The multiprotein Mediator complex is crucial for RNA polymerase II transcription in eukaryotes.
- In fission yeast, the Med15 protein is not a stable part of the core Mediator complex.
Purpose of the Study:
- To investigate the role and interactions of the Med15 protein in fission yeast.
- To understand the functional relationship between Med15, Hrp1, and the Mediator complex in gene regulation.
Main Methods:
- Protein complex isolation and characterization.
- Analysis of mRNA levels upon gene deletion.
- Genome-wide analysis of protein-DNA interactions at gene promoters.
Main Results:
- Med15 forms a stable subcomplex with the CHD1 chromatin-remodeling protein Hrp1.
- This Med15-Hrp1 subcomplex associates with the L-Mediator conformation but not the core Mediator.
- Deletion of med15(+) and hrp1(+) results in similar changes in global mRNA levels.
- Med15 binds to a specific subset of Hrp1-occupied gene promoters.
Conclusions:
- The Med15-Hrp1 complex represents a distinct functional module that interacts with Mediator.
- This interaction suggests a mechanism by which Mediator influences histone density at target gene promoters.
- Med15 and Hrp1 play significant roles in regulating global mRNA homeostasis.
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