Replication Coordination Marks the Domestication of Large Extrachromosomal Replicons in Bacteria
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PROVIDER: PRJEB85805 | ENA |
REPOSITORIES: ENA
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Project description:Bacteria with complex genomes including secondary chromosomes and/or megaplasmids face unique challenges when controlling their cell cycle: they not only need to coordinate genome replication with other cell cycle events such as cell growth and cell division, but also to synchronize the replication of different replicons. In Alphaproteobacteria, replication and maintenance of large extrachromosomal replicons is usually dependent on RepABC modules, as seen for the plant pathogen Agrobacterium tumefaciens. In this study, we demonstrate that the conserved GcrA protein is an essential methylation-dependent transcriptional regulator playing at least two critical roles during the A. tumefaciens cell cycle. First, GcrA is required for the on-time and synchronized firing of the three RepABC-dependent origins of replication of A. tumefaciens that are needed for chromosomal and megaplasmid replication. Second, GcrA triggers the expression of several essential cell division genes for the timely and essential assembly of a functional divisome. These findings highlight how this conserved global regulator can control and then synchronize a variety of essential cell cycle events in Alphaproteobacteria with complex genomes, notably coordinating the maintenance of several RepABC-dependent replicons with cell division.
2026-05-18 | GSE330725 | GEO
Project description:Chromatin conformation regulates the coordination between DNA replication and transcription
| PRJNA389460 | ENA
Project description:Chromatin structure affects DNA replication patterns, but the role of specific chromatin modifiers in regulating the replication process is yet unclear. We report that phosphorylation of the human SIRT1 deacetylase on Threonine 530 (T530-pSIRT1) modulates DNA synthesis. T530-pSIRT1 associates with replication origins and inhibits replication from a group of ÒdormantÓ potential replication origins, which initiate replication only when cells are subject to replication stress. Although both active and dormant origins bind T530-pSIRT1, active origins are distinguished from dormant origins by their unique association with an open chromatin mark, histone H3 methylated on lysine 4. SIRT1 phosphorylation also facilitates leading and lagging strand coordination. SIRT1 T530 phosphorylation is essential to prevent DNA breakage upon replication stress and cells harboring SIRT1 that cannot be phosphorylated exhibit a high prevalence of extrachromosomal elements, hallmarks of perturbed replication. These observations suggest that SIRT1 phosphorylation modulates the distribution of replication initiation events to insure genomic stability.
2017-06-02 | GSE94403 | GEO
Project description:DNA duplication is intimately connected to setting up post-replicative chromosome structures and events, but molecular details of this coordination are not well understood. A striking example occurs during yeast meiosis, where replication locally influences timing of the DNA double-strand breaks (DSBs) that initiate recombination. We show here that replication-DSB coordination is eliminated by overexpressing Dbf4-dependent Cdc7 kinase (DDK) or removing Tof1 or Csm3, components of the replication fork protection complex (FPC). DDK physically associates with Tof1, and Tof1 is dispensable for replication-DSB coordination if DDK is artificially tethered to replisomes. Furthermore, DDK phosphorylation of the DSB-promoting factor Mer2 is locally coordinated with replication, dependent on Tof1. These findings indicate that DDK recruited by FPC to replisomes phosphorylates chromatin-bound Mer2 in the wake of the replication fork, thus synchronizing replication with an early prerequisite for DSB formation. This may be a general mechanism to ensure spatial and temporal coordination of replication with other chromosomal processes. Forty-eight samples total: 8 time points from WT ARS+, WT arsM-bM-^HM-^F, DDK OP ARS+, DDK OP arsM-bM-^HM-^F,tof1M-bM-^HM-^F ARS+,tof1M-bM-^HM-^F arsM-bM-^HM-^F strains
2014-07-21 | E-GEOD-52987 | biostudies-arrayexpress
Project description:DNA duplication is intimately connected to setting up post-replicative chromosome structures and events, but molecular details of this coordination are not well understood. A striking example occurs during yeast meiosis, where replication locally influences timing of the DNA double-strand breaks (DSBs) that initiate recombination. We show here that replication-DSB coordination is eliminated by overexpressing Dbf4-dependent Cdc7 kinase (DDK) or removing Tof1 or Csm3, components of the replication fork protection complex (FPC). DDK physically associates with Tof1, and Tof1 is dispensable for replication-DSB coordination if DDK is artificially tethered to replisomes. Furthermore, DDK phosphorylation of the DSB-promoting factor Mer2 is locally coordinated with replication, dependent on Tof1. These findings indicate that DDK recruited by FPC to replisomes phosphorylates chromatin-bound Mer2 in the wake of the replication fork, thus synchronizing replication with an early prerequisite for DSB formation. This may be a general mechanism to ensure spatial and temporal coordination of replication with other chromosomal processes.
2014-07-21 | GSE52987 | GEO
Project description:Extrachromosomal DNA (ecDNA) amplification enhances intercellular oncogene dosage variability and accelerates tumor evolution by violating foundational principles of genetic inheritance through its asymmetric mitotic segregation. Spotlighting high-risk neuroblastoma we demonstrate how ecDNA amplification undermines the clinical efficacy of current therapies in cancers with extrachromosomal MYCN amplification. Integrating theoretical models of oncogene copy number-dependent fitness with single-cell ecDNA quantification and phenotype analyses, we reveal that ecDNA copy number heterogeneity drives phenotypic diversity and determines treatment sensitivity through mechanisms unattainable by chromosomal oncogene amplification. We demonstrate that ecDNA copy number directly influences critical cell fate decisions in cancer cell lines, patient-derived xenografts and primary neuroblastomas, illustrating how extrachromosomal oncogene dosage-driven phenotypic diversity offers a strong evolutionary advantage under therapeutic pressure. Furthermore, we identify senescent ecDNA-containing cells with reduced copy numbers in neuroblastomas and other MYC-amplified cancers as a source of treatment resistance and outline a strategy for their targeted elimination to improve the poor outcome of patients with MYCN-amplified cancers.
2025-07-05 | PXD064049 | Pride
Project description:DNA replication programs have been studied extensively in yeast and animal systems, where they have been shown to correlate with gene expression and certain epigenetic modifications. Despite the conservation of core DNA replication proteins, little is known about replication programs in plants. We used flow cytometry and tiling microarrays to profile DNA replication of Arabidopsis thaliana chromosome 4 (chr4) during early, mid, and late S phase. Replication profiles for early and mid S phase were similar and encompassed the majority of the euchromatin. Late S phase exhibited a distinctly different profile that includes the remaining euchromatin and essentially all of the heterochromatin. Termination zones were consistent between experiments, allowing us to define 163 putative replicons on chr4 that clustered into larger domains of predominately early or late replication. Early-replicating sequences, especially the initiation zones of early replicons, displayed a pattern of epigenetic modifications specifying an open chromatin conformation. Late replicons, and the termination zones of early replicons, showed an opposite pattern. Histone H3 acetylated on lysine 56 (H3K56ac) was enriched in early replicons, as well as the initiation zones of both early and late replicons. H3K56ac was also associated with expressed genes, but this effect was local whereas replication time correlated with H3K56ac over broad regions. The similarity of the replication profiles for early and mid S phase cells indicates that replication origin activation in euchromatin is stochastic. Replicon organization in Arabidopsis is strongly influenced by epigenetic modifications to histones and DNA. The domain organization of Arabidopsis is more similar to that in Drosophila than that in mammals, which may reflect genome size and complexity. The distinct patterns of association of H3K56ac with gene expression and early replication provide evidence that H3K56ac may be associated with initiation zones and replication origins.
2011-07-06 | GSE30433 | GEO
Project description:DNA replication programs have been studied extensively in yeast and animal systems, where they have been shown to correlate with gene expression and certain epigenetic modifications. Despite the conservation of core DNA replication proteins, little is known about replication programs in plants. We used flow cytometry and tiling microarrays to profile DNA replication of Arabidopsis thaliana chromosome 4 (chr4) during early, mid, and late S phase. Replication profiles for early and mid S phase were similar and encompassed the majority of the euchromatin. Late S phase exhibited a distinctly different profile that includes the remaining euchromatin and essentially all of the heterochromatin. Termination zones were consistent between experiments, allowing us to define 163 putative replicons on chr4 that clustered into larger domains of predominately early or late replication. Early-replicating sequences, especially the initiation zones of early replicons, displayed a pattern of epigenetic modifications specifying an open chromatin conformation. Late replicons, and the termination zones of early replicons, showed an opposite pattern. Histone H3 acetylated on lysine 56 (H3K56ac) was enriched in early replicons, as well as the initiation zones of both early and late replicons. H3K56ac was also associated with expressed genes, but this effect was local whereas replication time correlated with H3K56ac over broad regions. The similarity of the replication profiles for early and mid S phase cells indicates that replication origin activation in euchromatin is stochastic. Replicon organization in Arabidopsis is strongly influenced by epigenetic modifications to histones and DNA. The domain organization of Arabidopsis is more similar to that in Drosophila than that in mammals, which may reflect genome size and complexity. The distinct patterns of association of H3K56ac with gene expression and early replication provide evidence that H3K56ac may be associated with initiation zones and replication origins. Replicating DNA in cultured Arabidopsis cells was labeled with BrdU for 1 hour. Cells were harvested, nuclei extracted, and the nuclei were sorted by FACS as Early, Mid or Late S phase based on DNA content (DAPI signal). Newly replicated DNA was isolated by immunoprecipitation to BrdU, amplified, and labeled with Cy5/Cy3. Input DNA served as a reference and was labeled with Cy3/Cy5. Equal amounts of DNA was hybridized to a spotted cDNA that covers Arabidopsis chr4. Each S phase sample has 3 biological replicates with a dye swap serving as a technical replicate for a total of 18 arrays.
2011-07-06 | E-GEOD-30433 | biostudies-arrayexpress