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Differential sensitivity of gene expression in vitro to inhibitors of DNA gyrase
Abstract:
We have used the antibiotics coumermycin A1, novobiocin, and oxolinic acid, which are specific inhibitors of DNA gyrase, to study the coupled transcription and translation of several bacterial and plasmid genes in a DNA-directed cell-free system. The expression of different genes is reduced to different extents by inhibition of DNA gyrase activity. Among the genes tested, the lac operon, an rRNA gene, and the colicin gene of colicin E1 plasmid were found to be most sensitive, while the trp operon and some other genes in colicin E1 plasmid were relatively unaffected by the inhibitors. These results, together with earlier work on the transcription of circular DNA templates, indicate that DNA supercoiling can significantly enhance transcription from certain promoters.
Insights
DNA gyrase inhibitors like coumermycin A1 reveal that DNA supercoiling significantly enhances transcription for specific bacterial and plasmid genes, impacting gene expression differently. This study highlights supercoiling
Area of Science:
- Molecular Biology
- Genetics
- Microbiology
Background:
- DNA gyrase plays a crucial role in DNA replication and transcription.
- DNA supercoiling is essential for various DNA metabolic processes.
- Gene expression regulation is complex and influenced by DNA topology.
Purpose of the Study:
- To investigate the role of DNA gyrase activity in coupled transcription-translation.
- To determine how DNA supercoiling affects the expression of different bacterial and plasmid genes.
- To identify genes sensitive or insensitive to DNA gyrase inhibition.
Main Methods:
- Utilized a DNA-directed cell-free system.
- Employed specific DNA gyrase inhibitors: coumermycin A1, novobiocin, and oxolinic acid.
- Assessed the expression levels of various genes, including the lac operon, rRNA gene, trp operon, and colicin E1 plasmid genes.
Main Results:
- Inhibition of DNA gyrase activity differentially reduced gene expression.
- The lac operon, rRNA gene, and colicin E1 gene were highly sensitive to DNA gyrase inhibition.
- The trp operon and other colicin E1 plasmid genes showed relative insensitivity to the inhibitors.
Conclusions:
- DNA supercoiling significantly enhances transcription from specific promoters.
- The sensitivity of gene expression to DNA gyrase activity varies among different genes.
- DNA topology is a critical factor in regulating gene expression in bacteria.