Related Experiment Video
Updated: May 29, 2026
07:26
Discrimintion and Mapping of the Primary and Processed Transcripts in Maize Mitochondrion Using a Circular RT-PCR-based Strategy
Published on: July 29, 2019
Opening-closing dynamics of the mitochondrial transcription pre-initiation complex
Hajin Kim1, Guo-Qing Tang, Smita S Patel
1Physics Department and Center for Physics of Living Cells, University of Illinois, Urbana-Champaign, Howard Hughes Medical Institute, Urbana, IL 61801, USA.
Nucleic Acids Research
|September 14, 2011
Summary
Yeast mitochondrial RNA polymerase (Rpo41) and transcription factor Mtf1 dynamically regulate DNA opening for transcription initiation. Mtf1 stabilizes the open state, while ATP prolongs its duration, revealing key insights into initiation control.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Transcription initiation involves RNA polymerase and initiation factors recognizing promoter DNA.
- DNA local melting is a critical step preceding transcription.
- Understanding the dynamics of these processes is crucial for regulating gene expression.
Purpose of the Study:
- To investigate the dynamic behavior of the yeast mitochondrial transcription pre-initiation complex.
- To elucidate the roles of RNA polymerase (Rpo41), transcription factor (Mtf1), and ATP in promoter recognition and DNA melting.
Main Methods:
- Single-molecule fluorescence resonance energy transfer (smFRET) studies.
- Analysis of yeast Saccharomyces cerevisiae mitochondrial RNA polymerase (Rpo41) and transcription factor Mtf1 interactions.
- Investigating the effects of ATP on complex dynamics.
Main Results:
- The pre-initiation complex exhibits dynamic opening-closing transitions modulated by Mtf1 and ATP.
- Rpo41 alone briefly bends promoter DNA; Mtf1 enhances opening and stabilizes the open state.
- ATP prolongs the open state lifetime, supporting an 'ATP sensing mechanism'.
- Short-lived opening trials precede stable complex formation, aiding promoter selection.
Conclusions:
- Mtf1 plays dual roles in nucleating promoter opening and stabilizing the open complex.
- ATP acts as a key regulator, prolonging the open state and potentially sensing initiation readiness.
- The dynamic nature of open complex formation offers novel insights into transcription initiation regulation by RNA polymerase and transcription factors.
Related Concept Videos
01:37Energy to Drive Translocation
Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
Generally, polypeptides are unfolded by two distinct...
Generally, polypeptides are unfolded by two distinct...
01:53Bacterial Transcription
RNA polymerase (RNAP) carries out DNA-dependent RNA synthesis in both bacteria and eukaryotes. Bacteria do not have a membrane-bound nucleus. So, transcription and translation occur simultaneously, on the same DNA template.
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
01:47Transcription Initiation
Initiation is the first step of transcription in eukaryotes. Prokaryotic RNA Polymerase (RNAP) can bind to the template DNA and start transcribing. On the other hand, transcription in eukaryotes requires additional proteins, called transcription factors, to first bind to the promoter region in the DNA template. This binding helps recruit the specific RNAP that can assemble on the DNA and start transcription.
The promoters and enhancers and their accessory proteins allow tight regulation of...
The promoters and enhancers and their accessory proteins allow tight regulation of...
01:39Mitochondrial Precursor Proteins
Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial precursors...
Most of the mitochondrial precursors...
01:39Mitochondrial Protein Sorting
Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death. Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...