Hypernegative supercoiling of the DNA template during transcription elongation in vitro.

  title={Hypernegative supercoiling of the DNA template during transcription elongation in vitro.},
  author={Marc Drolet and X Bi and L. F. Liu},
  journal={The Journal of biological chemistry},
  volume={269 3},
Supercoiled plasmid DNAs with negative superhelicity several times higher than normal have been isolated from Escherichia coli topA mutants. The formation of these hypernegatively supercoiled plasmid DNAs is apparently induced by transcription. We show that hypernegatively supercoiled plasmid DNAs isolated from topA mutants contain R-loop(s). To study the mechanism of formation of hypernegatively supercoiled plasmid DNA, we have been able to reproduce hypernegatively supercoiled DNA in vitro… Expand
Relaxation of Transcription-induced Negative Supercoiling Is an Essential Function of Escherichia coli DNA Topoisomerase I*
Although the severity of the growth defect with both transcription-induced and global supercoiling was found, the result strongly suggests that the major function of DNA topoisomerase I is to relax local negative super coiling generated during transcription elongation. Expand
Coupling DNA Supercoiling to Transcription in Defined Protein Systems*
Under optimal conditions, the twin domain pathway of TCDS rapidly and efficiently generated superhelicity levels more than twice that typically found in vivo. Expand
Roles of DNA Topoisomerases in the Regulation of R-loop Formation in Vitro*
The strong transcription-induced relaxing activity of E. coli DNA topoisomerase I is shown to efficiently counteract the effect of DNA gyrase and thus inhibit extensive R-looping, and an R-Looped plasmid DNA is a better substrate for relaxation by E. bacteria as compared with a non-R-looped substrate. Expand
DNA supercoiling and transcription in bacteria: a two-way street
  • C. J. Dorman
  • Biology, Medicine
  • BMC Molecular and Cell Biology
  • 2019
These insights into fundamental molecular processes reveal mechanisms by which bacteria can prevail in unpredictable and often hostile environments by becoming unpredictable themselves. Expand
Potent stimulation of transcription-coupled DNA supercoiling by sequence-specific DNA-binding proteins
  • F. Leng, R. McMacken
  • Biology, Medicine
  • Proceedings of the National Academy of Sciences of the United States of America
  • 2002
It is suggested that some nucleoprotein complexes, perhaps those that contain sharply bent DNA, can form barriers that impede the diffusion and merger of independent chromosomal supercoil domains. Expand
The problem of hypernegative supercoiling and R-loop formation in transcription.
The results of this work show that an essential function of topoisomerase I is related to transcription, more precisely to inhibit R-loop formation, and may have revealed an important role for DNA supercoiling in modulating gene expression, not only at the level of transcription initiation but also during elongation. Expand
Escherichia coli DNA Topoisomerase I Inhibits R-loop Formation by Relaxing Transcription-induced Negative Supercoiling*
It is shown that stable R-loop formation duringin vitro transcription with E. coli RNA polymerase only occurs in the presence of DNA gyrase, and it is demonstrated that the coupling of transcription and translation in bacteria is an efficient way of preventing R- loop formation. Expand
Topoisomerase I Essentiality, DnaA-Independent Chromosomal Replication, and Transcription-Replication Conflict in Escherichia coli
This study confirms that topoisomerase I is essential for E. coli viability, and suggests that in its absence aberrant chromosomal DNA replication and excessive transcription-replication conflicts occur that are responsible for lethality. Expand
Inhibition of the gyrA promoter by transcription-coupled DNA supercoiling in Escherichia coli
It is shown that transient and localized TCDS strongly inhibits PgyrA in E. coli and this unique property of TCDS may be configured into a high throughput-screening (HTS) assay to identify antimicrobial compounds targeting bacterial DNA gyrase. Expand
DNA Topoisomerases Regulate R-loop Formation during Transcription of the rrnB Operon in Escherichia coli *
Genetic and biochemical evidence is presented strongly suggesting that R-loop formation can occur during transcription of a portion of the rrnB operon and that it is regulated by DNA topoisomerase activity. Expand