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Nucleosome-mediated cooperativity between transcription factors
1Harvard-MIT Division of Health Sciences and Technology, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. leonid@mit.edu
Summary
Strong gene expression control can occur without direct protein interactions. Nucleosomes, through competition, enable cooperative binding of transcription factors, similar to hemoglobin regulation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Precise gene expression relies on cooperative binding of transcription factors (TFs) to regulatory DNA.
- Classical models necessitate direct TF interactions, limiting TF site arrangements in regulatory regions.
- Genomic studies reveal flexibility in TF site arrangements, challenging direct interaction models.
Purpose of the Study:
- To demonstrate how transcription factor cooperativity can be achieved without direct interactions.
- To propose a novel mechanism of nucleosome-mediated cooperativity.
- To explore analogies between transcriptional regulation and hemoglobin cooperativity.
Main Methods:
- Theoretical modeling of TF-nucleosome interactions.
- Comparative analysis of transcriptional regulation and hemoglobin allostery.
- Review of existing genomic and functional studies on cis-regulatory regions.
Main Results:
- Non-interacting transcription factors can exhibit strong cooperativity by competing with nucleosomes.
- Nucleosome-mediated cooperativity offers flexibility and modularity in regulatory regions.
- The mechanism parallels heterotropic regulation in hemoglobin, like the Bohr effect.
- Nucleosome-positioning sequences and chromatin modifications play roles analogous to allosteric effectors.
Conclusions:
- Nucleosome-mediated cooperativity provides a flexible and general mechanism for gene regulation.
- This mechanism explains observations in genomic and evolutionary studies.
- The analogy with hemoglobin highlights a universal principle of cooperative binding in biological systems.
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