TEFM Enhances Transcription Elongation by Modifying mtRNAP Pausing Dynamics

Area of Science:

• Molecular Biology
• Genetics
• Biophysics

Background:

• Gene expression is tightly regulated at the transcription elongation stage.
• Mitochondrial RNA polymerase (mtRNAP) transcribes essential mitochondrial genes.
• Understanding factors influencing mtRNAP activity is crucial for mitochondrial function.

Purpose of the Study:

• To investigate the role of mitochondrial transcription elongation factor (TEFM) in enhancing mtRNAP transcription elongation.
• To elucidate the mechanism by which TEFM affects mtRNAP dynamics.
• To understand how mtRNAP navigates key DNA sequences like conserved sequence block II.

Main Methods:

• Employed a single-molecule optical-tweezers transcription assay.
• Monitored real-time transcription dynamics.
• Differentiated between pause-free elongation and transcriptional pauses.

Main Results:

• TEFM significantly enhances the stall force of mtRNAP.
• TEFM does not alter the pause-free elongation rate.
• TEFM reduces the frequency and duration of long-lived transcriptional pauses.
• Demonstrated mtRNAP's passage through conserved sequence block II.

Conclusions:

• TEFM enhances mtRNAP transcription elongation primarily by resolving transcriptional pauses.
• Both TEFM and specific mitochondrial DNA sequences are key regulators of transcription elongation dynamics.
• Findings provide insight into the control of mitochondrial gene expression.