Transcription elongation regulation is one of the key mechanisms employed to control gene expression. TEFM was recently reported as potential stimulator of mitochondrial transcription elongation by the single-subunit mitochondrial RNA polymerase (mtRNAP). In vitro biochemical transcription elongation assay verified that TEFM can resume elongation from pauses and pre-termination. We also demonstrated that TFAM, which is also required for transcription initiation, inhibited elongation. On the other hand, TEFM enhanced elongation and relieved TFAM-induced repression. Our findings suggested that the transcription elongation process by mitochondria RNAP is subjected to intricate regulation by multiple factors including TFAM, TEFM, and mitochondrial genomic DNA. To better understand the quan...[ Read more ]

Transcription elongation regulation is one of the key mechanisms employed to control gene expression. TEFM was recently reported as potential stimulator of mitochondrial transcription elongation by the single-subunit mitochondrial RNA polymerase (mtRNAP). In vitro biochemical transcription elongation assay verified that TEFM can resume elongation from pauses and pre-termination. We also demonstrated that TFAM, which is also required for transcription initiation, inhibited elongation. On the other hand, TEFM enhanced elongation and relieved TFAM-induced repression. Our findings suggested that the transcription elongation process by mitochondria RNAP is subjected to intricate regulation by multiple factors including TFAM, TEFM, and mitochondrial genomic DNA. To better understand the quantitative impact of TEFM on transcription elongation, in vitro single molecular transcription elongation assay was performed by optical tweezers. We demonstrated from the optical tweezers assay that TEFM does not change the pause-free velocity of transcription elongation process, but decreases the pause frequency and pause duration. our finding partially explains how TEFM enhances transcription elongation at single molecular lever and reveals the potential function and cooperation effect of TEFM to provide a new perspective to take insight into the regulation of transcription elongation.

Key words: Mitochondrial RNA Polymerase, Transcription Elongation, Optical Tweezers, Transcription Elongation Factor