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Updated: Apr 21, 2026
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Discrimintion and Mapping of the Primary and Processed Transcripts in Maize Mitochondrion Using a Circular RT-PCR-based Strategy
Published on: July 29, 2019
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Cryo-EM Structures Reveal Upstream DNA Interactions within the Mitochondrial Transcription Initiation Complex.
Rory E Shakey1, Caitlin Schroeder2, Xiangyu Deng1
1Department of BioSciences at Rice University, Houston, TX 77005, USA.
Biorxiv : the Preprint Server for Biology
|April 20, 2026
Summary
Mitochondrial transcription factor A (TFAM) shapes DNA architecture to stimulate transcription initiation. TFAM
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Mitochondrial DNA (mtDNA) transcription is vital for cellular energy production.
- The core transcription machinery involves transcription factor A (TFAM), transcription factor B2 (TFB2M), and mitochondrial RNA polymerase (PolRMT).
- Previous structural studies lacked insights into upstream regulatory DNA interactions during initiation.
Purpose of the Study:
- To elucidate the structural mechanisms of mitochondrial transcription initiation, focusing on upstream DNA interactions.
- To understand the role of TFAM in promoter binding and transcription regulation.
- To characterize the conformations of transcription initiation complexes.
Main Methods:
- X-ray crystallography to determine structures of TFAM-bound and TFAM-free initiation complexes.
- Biochemical assays to assess transcription activity upon promoter DNA manipulation.
- Site-directed mutagenesis to investigate specific protein-DNA interactions.
Main Results:
- Two distinct conformations of mitochondrial transcription initiation complexes were resolved: one bound to TFAM with extended upstream DNA, and another TFAM-free complex with short linear DNA.
- TFAM induces promoter bending, creating a transcription-stimulatory interface between PolRMT and the upstream promoter region (UPR).
- Truncation of the UPR reduces transcription, an effect dependent on the PolRMT interface, while TFAM-free complexes show inhibitory interactions of upstream DNA with PolRMT's tether helix.
Conclusions:
- TFAM plays a crucial role in regulating mitochondrial transcription by shaping promoter architecture and facilitating PolRMT interaction.
- The upstream promoter region and PolRMT's tether helix act as regulatory elements controlling transcription specificity.
- These findings provide a mechanistic understanding of how mitochondrial transcription initiation is coordinated and regulated.
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