DNA topoisomerase I acts as supercoiling sensor for transcription elongation in E. coli
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PROVIDER: PRJNA1144397 | ENA |
REPOSITORIES: ENA
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Project description:During transcription, RNA polymerase (RNAP) continuously unwinds and rewinds DNA, generating negative and positive supercoils upstream and downstream, respectively. Using single-particle cryo-EM, we elucidated how bacterial RNAP and DNA Topoisomerase I (TopoI), which relaxes negative supercoils, operate in close spatial proximity. TopoI binds to relaxed DNA upstream of RNAP and this involves a conformational switch in the TopoI functional domains. This suggests that TopoI exerts a sensing role prior to the formation of negative supercoils. On DNA substrates mimicking negatively supercoiled DNA, TopoI threads one strand into the active site for cleavage and binds the complementary strand with an auxiliary domain. Transcriptomic and phenotypic analyses suggest that mutations affecting the conformational changes in TopoI impact gene expression and operon polarity in bacteria. In summary, we propose a comprehensive model for DNA relaxation in proximity of active bacterial transcription.
2025-08-27 | GSE273976 | GEO
Project description:Reverse gyrase is a DNA topoisomerase that catalyzes positive DNA supercoiling in an ATP-dependent reaction. The enzyme consists of a helicase and a topoisomerase domain. The isolated helicase-like domain is a DNA-stimulated ATPase, and the isolated topoisomerase domain can relax supercoiled DNA. For positive supercoiling of DNA, the two domains need to cooperate, presumably through conformational changes. Here, we probed conformational changes of Thermotoga maritima reverse gyrase on DNA and nucleotide binding using hydrogen deuterium exchange (HDX). While ADPNP binding does not induce major conformational changes, binding of DNA leads to increased exposure of a region at the helicase-topoisomerase interface, encompassing R501 and E705, the side chains of which engage in electrostatic interactions. Removing the charges in an R501/E705A variant leads to a moderate increase in supercoiling activity, suggesting a slightly inhibitory role of this interactions. A R501/E705C variant, crosslinked to fix the two side chains in a disulphide bond, on the other hand, is inactive. Collectively these data show that rearrangements at the helicase and topoisomerase interface are important for the functional cooperation of the domains and for the enzymatic activity of reverse gyrase.
2026-08-24 | PXD074413 | Pride
Project description:We studied the response to increased DNA-supercoiling in Streptococcus pneumoniae by using seconeolitsine (SCN), a DNA topoisomerase I inhibitor. A homeostatic transcriptional response allowing recovering of supercoiling density was observed in cells treated with subinhibitory SCN concentrations. Supercoiling increases up to 40.7% (6 µM SCN) and 72.9% (8 µM SCN) were reverted to 8.5% and 44.1%, respectively. Likewise, recovery of viability and DNA-supercoiling were observed when cells were treated with those SCN concentrations and the drug was removed. The main DNA topoisomerase gene affected was topA, whose transcription depended on the supercoiling level. A two stage global transcriptomic response with 8 µM seconeolitsine was detected. The early stage (5 and 15 min, 10% of the genome) represented a response induced by increased supercoiling. The second stage represented supercoiling recovery (30 min, 2.0% of the genome). Almost 25% of the early responsive genes formed clusters with coordinated transcriptional regulation. Twelve clusters were evident, with sizes of 6.7 to 31.4 Kb (9 to 22 responsive genes). Strikingly, clusters did not contradict those observed under DNA relaxation, suggesting that bacteria manage supercoiling stress using overlapping responses. This is the first study describing a global transcriptomic response triggered by an increase in DNA supercoiling in bacteria. RNA was extracted from S. pneumoniae R6 cultures during exponential growth, amplified and used for microarray hibridization. Two independent replicates were performed.
2016-07-07 | E-GEOD-77587 | biostudies-arrayexpress
Project description:DNA supercoiling has the potential to alter gene transcription and chromatin topology, yet how its distribution is regulated on a genome-wide level is poorly understood. Here we utilized psoralen crosslinking and sequencing (TMP-seq) to assess the distribution of underwound DNA at high resolution in postmitotic neurons. We report that supercoiling propagates widely (> 200 kb) from the sites of active RNAPII and that its distribution is constrained by chromosome compartments and by specific nucleosome configurations, including H3K27me3-rich regions and broad distributions of active promoter-related chromatin marks. Underwound DNA does not accrue upstream of expressed genes in postmitotic neurons, which could shield them from cumulative torsional stress. Inhibiting either transcription or TOP1 affect underwound DNA levels genome-wide; however, supercoiling at the boundaries of expressed genes is minimally perturbed, indicating that dynamic supercoiling is not locally confined to sites of RNAPII activity at expressed genes. Surprisingly, TOP1 inhibition elevates supercoiling but stimulates nascent transcription at most genes and other sites of transcription, including enhancers, suggesting that torsional stress generally favors transcription, and that topoisomerase activity is not essential for transcription at most genes. We show that the induction of cryptic transcription within gene bodies, and not supercoiling buildup, could underlie the vulnerability of long neuronal genes to topoisomerase inhibition. These observations illuminate how chromatin organization governs the distribution of torsional stress within the genome and how the interplay of supercoiling and topoisomerases regulates transcription.
2026-07-14 | GSE231609 | GEO
Project description:DNA supercoiling has the potential to alter gene transcription and chromatin topology, yet how its distribution is regulated on a genome-wide level is poorly understood. Here we utilized psoralen crosslinking and sequencing (TMP-seq) to assess the distribution of underwound DNA at high resolution in postmitotic neurons. We report that supercoiling propagates widely (> 200 kb) from the sites of active RNAPII and that its distribution is constrained by chromosome compartments and by specific nucleosome configurations, including H3K27me3-rich regions and broad distributions of active promoter-related chromatin marks. Underwound DNA does not accrue upstream of expressed genes in postmitotic neurons, which could shield them from cumulative torsional stress. Inhibiting either transcription or TOP1 affect underwound DNA levels genome-wide; however, supercoiling at the boundaries of expressed genes is minimally perturbed, indicating that dynamic supercoiling is not locally confined to sites of RNAPII activity at expressed genes. Surprisingly, TOP1 inhibition elevates supercoiling but stimulates nascent transcription at most genes and other sites of transcription, including enhancers, suggesting that torsional stress generally favors transcription, and that topoisomerase activity is not essential for transcription at most genes. We show that the induction of cryptic transcription within gene bodies, and not supercoiling buildup, could underlie the vulnerability of long neuronal genes to topoisomerase inhibition. These observations illuminate how chromatin organization governs the distribution of torsional stress within the genome and how the interplay of supercoiling and topoisomerases regulates transcription.
2026-07-14 | GSE231608 | GEO
Project description:DNA supercoiling has the potential to alter gene transcription and chromatin topology, yet how its distribution is regulated on a genome-wide level is poorly understood. Here we utilized psoralen crosslinking and sequencing (TMP-seq) to assess the distribution of underwound DNA at high resolution in postmitotic neurons. We report that supercoiling propagates widely (> 200 kb) from the sites of active RNAPII and that its distribution is constrained by chromosome compartments and by specific nucleosome configurations, including H3K27me3-rich regions and broad distributions of active promoter-related chromatin marks. Underwound DNA does not accrue upstream of expressed genes in postmitotic neurons, which could shield them from cumulative torsional stress. Inhibiting either transcription or TOP1 affect underwound DNA levels genome-wide; however, supercoiling at the boundaries of expressed genes is minimally perturbed, indicating that dynamic supercoiling is not locally confined to sites of RNAPII activity at expressed genes. Surprisingly, TOP1 inhibition elevates supercoiling but stimulates nascent transcription at most genes and other sites of transcription, including enhancers, suggesting that torsional stress generally favors transcription, and that topoisomerase activity is not essential for transcription at most genes. We show that the induction of cryptic transcription within gene bodies, and not supercoiling buildup, could underlie the vulnerability of long neuronal genes to topoisomerase inhibition. These observations illuminate how chromatin organization governs the distribution of torsional stress within the genome and how the interplay of supercoiling and topoisomerases regulates transcription.
2026-07-14 | GSE231610 | GEO
Project description:DNA supercoiling has the potential to alter gene transcription and chromatin topology, yet how its distribution is regulated on a genome-wide level is poorly understood. Here we utilized psoralen crosslinking and sequencing (TMP-seq) to assess the distribution of underwound DNA at high resolution in postmitotic neurons. We report that supercoiling propagates widely (> 200 kb) from the sites of active RNAPII and that its distribution is constrained by chromosome compartments and by specific nucleosome configurations, including H3K27me3-rich regions and broad distributions of active promoter-related chromatin marks. Underwound DNA does not accrue upstream of expressed genes in postmitotic neurons, which could shield them from cumulative torsional stress. Inhibiting either transcription or TOP1 affect underwound DNA levels genome-wide; however, supercoiling at the boundaries of expressed genes is minimally perturbed, indicating that dynamic supercoiling is not locally confined to sites of RNAPII activity at expressed genes. Surprisingly, TOP1 inhibition elevates supercoiling but stimulates nascent transcription at most genes and other sites of transcription, including enhancers, suggesting that torsional stress generally favors transcription, and that topoisomerase activity is not essential for transcription at most genes. We show that the induction of cryptic transcription within gene bodies, and not supercoiling buildup, could underlie the vulnerability of long neuronal genes to topoisomerase inhibition. These observations illuminate how chromatin organization governs the distribution of torsional stress within the genome and how the interplay of supercoiling and topoisomerases regulates transcription.
2026-07-14 | GSE231690 | GEO
Project description:We studied the response to increased DNA-supercoiling in Streptococcus pneumoniae by using seconeolitsine (SCN), a DNA topoisomerase I inhibitor. A homeostatic transcriptional response allowing recovering of supercoiling density was observed in cells treated with subinhibitory SCN concentrations. Supercoiling increases up to 40.7% (6 µM SCN) and 72.9% (8 µM SCN) were reverted to 8.5% and 44.1%, respectively. Likewise, recovery of viability and DNA-supercoiling were observed when cells were treated with those SCN concentrations and the drug was removed. The main DNA topoisomerase gene affected was topA, whose transcription depended on the supercoiling level. A two stage global transcriptomic response with 8 µM seconeolitsine was detected. The early stage (5 and 15 min, 10% of the genome) represented a response induced by increased supercoiling. The second stage represented supercoiling recovery (30 min, 2.0% of the genome). Almost 25% of the early responsive genes formed clusters with coordinated transcriptional regulation. Twelve clusters were evident, with sizes of 6.7 to 31.4 Kb (9 to 22 responsive genes). Strikingly, clusters did not contradict those observed under DNA relaxation, suggesting that bacteria manage supercoiling stress using overlapping responses. This is the first study describing a global transcriptomic response triggered by an increase in DNA supercoiling in bacteria. Total RNA was extracted from S. pneumoniae R6 cultures during exponential growth and used for RNA-Seq. Two independent replicates per condition were performed.
2016-07-07 | E-GEOD-77748 | biostudies-arrayexpress
Project description:We studied the response to increased DNA-supercoiling in Streptococcus pneumoniae by using seconeolitsine (SCN), a DNA topoisomerase I inhibitor. A homeostatic transcriptional response allowing recovering of supercoiling density was observed in cells treated with subinhibitory SCN concentrations. Supercoiling increases up to 40.7% (6 µM SCN) and 72.9% (8 µM SCN) were reverted to 8.5% and 44.1%, respectively. Likewise, recovery of viability and DNA-supercoiling were observed when cells were treated with those SCN concentrations and the drug was removed. The main DNA topoisomerase gene affected was topA, whose transcription depended on the supercoiling level. A two stage global transcriptomic response with 8 µM seconeolitsine was detected. The early stage (5 and 15 min, 10% of the genome) represented a response induced by increased supercoiling. The second stage represented supercoiling recovery (30 min, 2.0% of the genome). Almost 25% of the early responsive genes formed clusters with coordinated transcriptional regulation. Twelve clusters were evident, with sizes of 6.7 to 31.4 Kb (9 to 22 responsive genes). Strikingly, clusters did not contradict those observed under DNA relaxation, suggesting that bacteria manage supercoiling stress using overlapping responses. This is the first study describing a global transcriptomic response triggered by an increase in DNA supercoiling in bacteria.
2016-07-07 | GSE77587 | GEO
Project description:We studied the response to increased DNA-supercoiling in Streptococcus pneumoniae by using seconeolitsine (SCN), a DNA topoisomerase I inhibitor. A homeostatic transcriptional response allowing recovering of supercoiling density was observed in cells treated with subinhibitory SCN concentrations. Supercoiling increases up to 40.7% (6 µM SCN) and 72.9% (8 µM SCN) were reverted to 8.5% and 44.1%, respectively. Likewise, recovery of viability and DNA-supercoiling were observed when cells were treated with those SCN concentrations and the drug was removed. The main DNA topoisomerase gene affected was topA, whose transcription depended on the supercoiling level. A two stage global transcriptomic response with 8 µM seconeolitsine was detected. The early stage (5 and 15 min, 10% of the genome) represented a response induced by increased supercoiling. The second stage represented supercoiling recovery (30 min, 2.0% of the genome). Almost 25% of the early responsive genes formed clusters with coordinated transcriptional regulation. Twelve clusters were evident, with sizes of 6.7 to 31.4 Kb (9 to 22 responsive genes). Strikingly, clusters did not contradict those observed under DNA relaxation, suggesting that bacteria manage supercoiling stress using overlapping responses. This is the first study describing a global transcriptomic response triggered by an increase in DNA supercoiling in bacteria.
2016-07-07 | GSE77748 | GEO