Transcriptional accuracy modeling suggests two-step proofreading by RNA polymerase

Area of Science:

• Molecular Biology
• Biophysics
• Genetics

Background:

• RNA polymerase (RNAP) proofreading is crucial for maintaining genetic fidelity during transcription.
• Previous models often simplify the complex mechanisms of nucleotide selection and error correction.
• Experimental data indicate RNAP cleaves at least 2 nucleotides and elongation slows after misincorporation.

Purpose of the Study:

• To propose a novel two-step proofreading mechanism for mRNA transcription.
• To extend existing models of nucleotide selection accuracy in RNA polymerase-dependent transcription.
• To derive base selection accuracy from experimentally estimated nearest-neighbor parameters.

Main Methods:

• Development of a theoretical model for a two-step proofreading mechanism in mRNA transcription.
• Integration of experimental observations on transcript cleavage and elongation rates.
• Derivation of initial and proofreading base selection accuracy using nearest-neighbor parameters.

Main Results:

• The model describes two sequential rounds of proofreading selection in mRNA transcription.
• It quantifies accuracy enhancement from polymerase revisiting positions after transcript cleavage.
• The model successfully integrates experimental data on cleavage and elongation kinetics.

Conclusions:

• A novel two-step proofreading mechanism enhances mRNA transcription accuracy.
• The model provides a more comprehensive description of nucleotide selection fidelity.
• This mechanism contributes to the overall accuracy of genetic information transfer.