Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Differential roles of positive and negative supercoiling in organizing the E. coli genome

ABSTRACT: This study aims to explore whether and how positive and negative supercoiling contribute to the three-dimensional (3D) organization of the bacterial genome. We used recently published Escherichia coli GapR ChIP-seq and TopoI ChIP-seq (also called EcTopoI-seq) data, which marks positive and negative supercoiling sites, respectively, to study how supercoiling correlates with the spatial contact maps obtained from chromosome conformation capture sequencing (Hi-C and 5C). We find that supercoiled chromosomal loci have overall higher Hi-C contact frequencies than sites that are not supercoiled. Surprisingly, positive supercoiling corresponds to higher spatial contact than negative supercoiling. Additionally, positive, but not negative, supercoiling could be identified from Hi-C data with high accuracy. We further find that the majority of positive and negative supercoils coincide with highly active transcription units, with a minor group associated with replication and other genomic processes. Our results show that both positive and negative supercoiling enhance spatial contact, with positive supercoiling playing a larger role in bringing genomic loci closer in space. Based on our results, we propose new physical models of how the E. coli chromosome is organized by positive and negative supercoils.

ORGANISM(S): Escherichia coli str. K-12 substr. MG1655

PROVIDER: GSE214856 | GEO | 2023/11/03

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

High-resolution, genome-wide mapping of positive supercoiling in chromosomes [ecChIP]

Project description:Supercoiling impacts DNA replication, transcription, protein binding to DNA, and the three- dimensional organization of chromosomes. However, there are currently no methods to directly interrogate or map positive supercoils, so their distribution in genomes remains unknown. Here, we describe a method, GapR-seq, based on the chromatin immunoprecipitation of GapR, a bacterial protein that preferentially recognizes overtwisted DNA, for generating high-resolution maps of positive supercoiling. Applying this method to E. coli and S. cerevisiae, we find that positive supercoiling is widespread, associated with transcription, and particularly enriched between convergently-oriented genes, consistent with the “twin-domain” model of supercoiling. In yeast, we also find positive supercoils associated with centromeres, cohesin binding sites, autonomously replicating sites, and the borders of R-loops (DNA-RNA hybrids). Our results suggest that GapR-seq is a powerful approach, likely applicable in any organism, to investigate aspects of chromosome structure and organization not accessible by Hi-C or other existing methods.

2021-06-25 | GSE152880 | GEO

High-resolution, genome-wide mapping of positive supercoiling in chromosomes [RNA-seq]

2021-06-25 | GSE152879 | GEO

High-resolution, genome-wide mapping of positive supercoiling in chromosomes [yChIP]

Project description:Supercoiling impacts DNA replication, transcription, protein binding to DNA, and the three-dimensional organization of chromosomes. However, there are currently no methods to directly interrogate or map positive supercoils, so their distribution in genomes remains unknown. Here, we describe a method based on the chromatin immunoprecipitation of GapR, a bacterial protein that preferentially recognizes overtwisted DNA, for generating high-resolution maps of positive supercoiling. Applying this method to E. coli and S. cerevisiae, we find that positive supercoiling is widespread, associated with transcription, and enriched between convergently-oriented genes, consistent with the ?twin-domain? model of supercoiling. In yeast, we also find positive supercoils associated with centromeres, cohesin binding sites, replication-transcription encounters, and the borders of R-loops (DNA-RNA hybrids). Our results suggest that GapR-seq is a powerful approach that can be applied in any organism to investigate aspects of chromosome structure and organization not accessible by Hi-C or other existing methods.

2021-06-25 | GSE152881 | GEO

High-resolution, genome-wide mapping of positive supercoiling in chromosomes [RNA-Seq 2]

Project description:Supercoiling impacts DNA replication, transcription, protein binding to DNA, and the three-dimensional organization of chromosomes. However, there are currently no methods to directly interrogate or map positive supercoils, so their distribution in genomes remains unknown. Here, we describe a method based on the chromatin immunoprecipitation of GapR, a bacterial protein that preferentially recognizes overtwisted DNA, for generating high-resolution maps of positive supercoiling. Applying this method to E. coli and S. cerevisiae, we find that positive supercoiling is widespread, associated with transcription, and enriched between convergently-oriented genes, consistent with the “twin-domain” model of supercoiling. In yeast, we also find positive supercoils associated with centromeres, cohesin binding sites, replication-transcription encounters, and the borders of R-loops (DNA-RNA hybrids). Our results suggest that GapR-seq is a powerful approach that can be applied in any organism to investigate aspects of chromosome structure and organization not accessible by Hi-C or other existing methods.

2021-06-25 | GSE164186 | GEO

A bacterial chromosome structuring protein binds overtwisted DNA to stimulate type II topoisomerases and enable DNA replication

Project description:When DNA is unwound during replication, it becomes overtwisted and forms positive supercoils in front of the translocating DNA polymerase. Unless removed or dissipated, this superhelical tension can impede replication elongation. Topoisomerases, including gyrase and topoisomerase IV in bacteria, are required to relax positive supercoils ahead of DNA polymerase, but may not be sufficient for replication. Here, we find that GapR, a chromosome structuring protein in Caulobacter crescentus, is required to complete DNA replication. GapR associates in vivo with positively supercoiled chromosomal DNA, and our biochemical and structural studies demonstrate that GapR forms a dimer-of-dimers that fully encircles overtwisted DNA. Further, we show that GapR stimulates gyrase and topo IV to relax positive supercoils, thereby enabling DNA replication. Analogous chromosome structuring proteins that locate to the overtwisted DNA in front of replication forks may be present in other organisms, similarly helping to recruit and stimulate topoisomerases during DNA replication.

2018-09-13 | GSE100657 | GEO

RNA Polymerase-II-generated DNA supercoils destabilize nucleosomes

Project description:The twin supercoiled domain model posits that, as RNA Polymerase II (Pol II) transcribes a gene, it generates negative and positive supercoils upstream and downstream respectively, but little is known about the functional consequence in vivo of the resulting torsional strain. Here we provide a method for high resolution mapping of DNA supercoils using next-generation sequencing, and show that the level of supercoiling is correlated with gene expression in Drosophila cells. Inhibition of topoisomerases, enzymes that relieve torsional strain, leads to accumulation of supercoils surrounding gene bodies and of Pol II at the transcription start sites. Topoisomerase I inhibition results in increased nascent RNA transcripts with Topoisomerase II inhibition shows little change in nascent RNA levels. Despite these different effects on transcription, inhibition of either enzyme results in increased nucleosome turnover within gene bodies, suggesting that torsional stress contributes to destabilizing nucleosomes ahead of Pol II. 12 paired-end samples and 8 single-end samples were sequenced and analyzed.

2013-10-31 | E-GEOD-47795 | biostudies-arrayexpress

RNA Polymerase-II-generated DNA supercoils destabilize nucleosomes

2013-10-31 | GSE47795 | GEO

Loop-extruding Smc5/6 organizes transcription-induced positive DNA supercoils [ChIP-seq]

Project description:The Structural Maintenance of Chromosome (SMC) protein complexes cohesin, condensin and the Smc5/6 complex (Smc5/6) are essential for chromosome function. At the molecular level, these complexes fold DNA by loop extrusion. Accordingly, cohesin creates chromosome loops in interphase, and condensin compacts mitotic chromosomes. However, the role of Smc5/6’s recently discovered DNA loop extrusion activity is unknown. Here, we uncover that Smc5/6 controls the spatial organization of supercoiled chromosomal regions. The results show that Smc5/6 associates with transcription-induced positively supercoiled chromosomal DNA at cohesin-dependent chromosome loop boundaries. Mechanistically, single-molecule imaging reveals that dimers of Smc5/6 specifically recognize the tip of positively supercoiled DNA plectonemes, and efficiently initiates loop extrusion to gather the supercoiled DNA into a large plectonemic loop. Finally, Hi-C analysis shows that Smc5/6 links chromosomal regions containing transcription-induced positive supercoiling in cis. Altogether, our findings indicate that Smc5/6 controls the three-dimensional organization of chromosomes by recognizing and initiating loop extrusion on positively supercoiled DNA.

2024-01-30 | GSE235557 | GEO

Loop-extruding Smc5/6 organizes transcription-induced positive DNA supercoils [RNA-seq]

2024-01-30 | GSE235559 | GEO

Loop-extruding Smc5/6 organizes transcription-induced positive DNA supercoils [Hi-C]

2024-01-30 | GSE235558 | GEO