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RNA polymerase induces DNA bending at yeast mitochondrial promoters
A H Schinkel1, M J Groot Koerkamp, A W Teunissen
1Laboratory of Biochemistry, University of Amsterdam, The Netherlands.
Abstract:
Yeast mitochondrial RNA polymerase can bind specifically to promoter-containing DNA fragments in vitro as detected by DNAse I or methidiumpropyl-EDTA. Fe(II) protection assays and gel retardation experiments. Retardation of RNA polymerase-DNA complexes was most pronounced when the promoter was located in the middle of a DNA fragment and was diminished when RNA polymerase was bound near one of the ends. This indicates that upon RNA polymerase-binding the DNA undergoes a conformational change which is most likely a bend. The degree of introduced bending correlated with the efficiency of transcription and promoter-binding in a series of promoter mutants, suggesting that bending is a functional event during promoter utilisation.
Insights
Yeast mitochondrial RNA polymerase binding to DNA induces a bend, crucial for efficient transcription. This DNA conformational change is key to promoter utilization and gene expression regulation.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Yeast mitochondrial RNA polymerase is essential for gene expression.
- Understanding promoter recognition is key to gene regulation.
Purpose of the Study:
- To investigate the interaction between yeast mitochondrial RNA polymerase and DNA.
- To determine if DNA undergoes conformational changes upon polymerase binding.
- To assess the functional significance of these changes in promoter utilization.
Main Methods:
- DNAse I and methidiumpropyl-EDTA. Fe(II) protection assays.
- Gel retardation experiments to analyze RNA polymerase-DNA complex formation.
- Analysis of promoter mutants to correlate DNA bending with transcription efficiency.
Main Results:
- Yeast mitochondrial RNA polymerase specifically binds to promoter-containing DNA fragments in vitro.
- DNA undergoes a conformational change, likely a bend, upon RNA polymerase binding.
- The degree of DNA bending correlates with promoter binding efficiency and transcriptional output.
Conclusions:
- DNA bending induced by yeast mitochondrial RNA polymerase is a functional event.
- This bending mechanism plays a significant role in promoter recognition and utilization.
- The findings provide insights into the regulation of mitochondrial gene expression.