Collective RNAP Dynamics Link Transcriptional Strength to Fidelity.

Area of Science:

• Molecular Biology
• Biophysics
• Genetics

Background:

• Transcription fidelity is inversely related to gene expression strength.
• Factors like histone modifications and DNA methylation influence transcription but don't fully explain the fidelity-strength relationship.
• The precise mechanisms linking high transcription rates to increased errors are not well understood.

Purpose of the Study:

• To investigate the role of repulsive interactions between co-transcribing RNA polymerases (RNAPs) in the fidelity-strength coupling.
• To develop a quantitative model explaining how RNAP dynamics affect transcriptional accuracy.
• To provide mechanistic insights into why highly expressed genes have higher error rates.

Main Methods:

• Development of a stochastic kinetic model for transcription elongation.
• Incorporation of kinetic proofreading and repulsive forces between neighboring RNAPs.
• Analysis of how RNAP collisions affect elongation speed and proofreading efficiency.

Main Results:

• Repulsive forces between RNAPs accelerate leading polymerases but hinder their kinetic proofreading.
• Trailing RNAPs experience opposite effects, with reduced speed and enhanced proofreading.
• High initiation rates and RNAP interactions significantly increase transcriptional error rates.
• Force partitioning between translocation and backtracking primarily affects elongation speed, not fidelity.

Conclusions:

• RNAP-RNAP interactions provide a mechanistic explanation for the fidelity-strength relationship in transcription.
• Collective RNAP dynamics intrinsically compromise fidelity at high expression levels.
• The study offers new physical insights into transcriptional regulation and error production.