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Transcription-generated torsional stress destabilizes nucleosomes
Sheila S Teves1, Steven Henikoff2
11] Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA. [2] Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, USA.
Nature Structural & Molecular Biology
|December 10, 2013
Summary
Torsional stress during gene transcription destabilizes nucleosomes. This study maps underwound DNA in Drosophila cells, linking torsion to gene expression and showing topoisomerase inhibition increases nucleosome turnover.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- RNA polymerase II (Pol II) must navigate nucleosomes during transcription.
- Torsional stress generated during transcription is hypothesized to destabilize nucleosomes.
- In vivo mechanisms of Pol II traversal through nucleosomal arrays are not fully understood.
Purpose of the Study:
- To develop a high-resolution method for mapping underwound DNA.
- To investigate the correlation between DNA torsion and gene expression in vivo.
- To elucidate the role of torsional stress in nucleosome dynamics during transcription.
Main Methods:
- High-resolution mapping of underwound DNA using next-generation sequencing.
- Inhibition of topoisomerases (I and II) to induce torsional stress.
- Analysis of Pol II occupancy, nascent RNA transcripts, and nucleosome turnover.
Main Results:
- DNA torsion levels were found to be correlated with gene expression in Drosophila melanogaster cells.
- Topoisomerase inhibition led to increased Pol II at transcription start sites.
- Inhibition of topoisomerases increased nucleosome turnover and salt solubility within gene bodies, independent of Pol II elongation effects.
Conclusions:
- Torsional stress plays a significant role in regulating nucleosome dynamics during transcription.
- The study provides a method for mapping DNA torsion and links it to gene expression.
- Torsional stress contributes to nucleosome destabilization through elongation-independent mechanisms.
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