Stochastic Model of Supercoiling-Dependent Transcription

Area of Science:

• Molecular Biology
• Biophysics
• Genetics

Background:

• DNA supercoiling is a critical factor influencing DNA structure and function.
• Gene transcription involves DNA unwinding by polymerases, which induces supercoiling.
• Enzyme binding to DNA is affected by local DNA topology, including unwound regions.

Purpose of the Study:

• To develop a stochastic model for gene transcription coupled to DNA supercoiling.
• To investigate the impact of transcriptionally induced supercoiling on gene expression patterns.
• To explore the regulatory role of DNA topology in gene regulation.

Main Methods:

• Development of a stochastic model incorporating polymerase activity and DNA supercoiling dynamics.
• Analysis of model behavior under varying levels of supercoiling flux.
• Simulation of gene transcription under different topological stress regimes.

Main Results:

• A sharp crossover in gene transcription behavior was observed with increasing supercoiling.
• High supercoiling levels lead to correlated gene expression, transcriptional bursts, and supercoiling waves.
• Divergent and bidirectional gene expression is upregulated in the high supercoiling regime.
• Topological enzymes that relax DNA twist and writhe were predicted to downregulate transcription.

Conclusions:

• DNA supercoiling plays a crucial role in regulating gene transcription, transitioning it from random to tightly controlled expression.
• The model predicts emergent phenomena like transcriptional bursting and coordinated gene regulation driven by supercoiling.
• Targeting enzymes involved in DNA topology management offers a potential strategy for modulating gene transcription.