Multiscale structuring of the E. coli chromosome by nucleoid-associated and condensin proteins
Ontology highlight
ABSTRACT:
ORGANISM(S): Escherichia coli str. K-12 substr. MG1655
PROVIDER: GSE107301 | GEO | 2017/12/07
SECONDARY ACCESSION(S): PRJNA421326
REPOSITORIES: GEO
Similar Datasets
Project description:To fit within the confines of the cell, bacterial chromosomes are highly condensed into a structure called the nucleoid. Despite the high degree of compaction in the nucleoid, the genome remains accessible to essential biological processes, such as replication and transcription. Here, we present the first high-resolution chromosome conformation capture-based molecular analysis of the spatial organization of the Escherichia coli nucleoid during rapid growth in rich medium and following an induced amino acid starvation that promotes the stringent response. Our analyses identify the presence of origin and terminus domains in exponentially growing cells. Moreover, we observe an increased number of interactions within the origin domain and significant clustering of SeqA-binding sequences, suggesting a role for SeqA in clustering of newly replicated chromosomes. By contrast, ‘histone-like’ protein (i.e. Fis, IHF and H-NS) binding sites did not cluster, and their role in global nucleoid organization does not manifest through the mediation of chromosomal contacts. Finally, genes that were downregulated after induction of the stringent response were spatially clustered, indicating that transcription in E. coli occurs at transcription foci. A 4 chips study of exponentially growing wild type E. coli strain MG1655 grown in LB rich media or after induction of the stringent response by serine hydroxamate for 30 min. Two technical replicates, Three biological replicates mixed prior hybridization on the chip.
2013-05-01 | E-GEOD-40304 | biostudies-arrayexpress
Project description:To fit within the confines of the cell, bacterial chromosomes are highly condensed into a structure called the nucleoid. Despite the high degree of compaction in the nucleoid, the genome remains accessible to essential biological processes, such as replication and transcription. Here, we present the first high-resolution chromosome conformation capture-based molecular analysis of the spatial organization of the Escherichia coli nucleoid during rapid growth in rich medium and following an induced amino acid starvation that promotes the stringent response. Our analyses identify the presence of origin and terminus domains in exponentially growing cells. Moreover, we observe an increased number of interactions within the origin domain and significant clustering of SeqA-binding sequences, suggesting a role for SeqA in clustering of newly replicated chromosomes. By contrast, ‘histone-like’ protein (i.e. Fis, IHF and H-NS) binding sites did not cluster, and their role in global nucleoid organization does not manifest through the mediation of chromosomal contacts. Finally, genes that were downregulated after induction of the stringent response were spatially clustered, indicating that transcription in E. coli occurs at transcription foci.
2013-05-01 | GSE40304 | GEO
Project description:The Escherichia coli nucleoid is confined within a rod shaped cell many times smaller than the outstretched chromosome. While extensive compaction is necessary for this process, the chromosome must at the same time remain accessible to essential cellular processes such as replication and transcription. Currently, the individual contributions of cellular confinement, chromosome topology, replication and transcription on nucleoid organization are not well understood. Here we synchronize E. coli cells in stationary phase, where replication has ceased, each cell contains only one copy of the chromosome, and transcription is minimal. We then release the cells and capture chromosome contacts and transcription immediately following release and through-out one cell cycle. Polymer models of confined and topologically constrained circular polymers revealed that cellular confinement and topology do not contribute extensively to the organization of the E. coli nucleoid. Rather, local nucleoid structure is established concurrent with replication, and higher order organization is formed by the replication dependant clustering of linearly distant SeqA bound sites and cell cycle specific gene transcription.
2017-12-25 | GSE87117 | GEO
Project description:The Escherichia coli nucleoid is confined within a rod shaped cell many times smaller than the outstretched chromosome. While extensive compaction is necessary for this process, the chromosome must at the same time remain accessible to essential cellular processes such as replication and transcription. Currently, the individual contributions of cellular confinement, chromosome topology, replication and transcription on nucleoid organization are not well understood. Here we synchronize E. coli cells in stationary phase, where replication has ceased, each cell contains only one copy of the chromosome, and transcription is minimal. We then release the cells and capture chromosome contacts and transcription immediately following release and through-out one cell cycle. Polymer models of confined and topologically constrained circular polymers revealed that cellular confinement and topology do not contribute extensively to the organization of the E. coli nucleoid. Rather, local nucleoid structure is established concurrent with replication, and higher order organization is formed by the replication dependant clustering of linearly distant SeqA bound sites and cell cycle specific gene transcription.
2017-12-25 | GSE87071 | GEO
Project description:Coordination of chromosome segregation and cytokinesis is crucial for efficient cell proliferation. In Bacillus subtilis the nucleoid occlusion protein Noc protects chromosomes by associating with the chromosome and preventing cell division in its vicinity. Using protein localization, ChAP-on-Chip and bioinformatics, we have identified a consensus Noc-binding DNA sequence (NBS), and show that Noc is targeted to about 70 discrete regions scattered around the chromosome, though absent from a large region around the replication terminus. Purified Noc bound specifically to an NBS in vitro. NBSs inserted near the replication terminus bound Noc-YFP and caused a delay in cell division. An autonomous plasmid carrying an NBS recruited Noc-YFP and conferred a severe Noc-dependent inhibition of cell division. This shows that Noc is a potent inhibitor of division but that its activity is strictly localized by interaction with NBS sites in vivo. We propose that Noc not only serves as a spatial regulator of cell division to protect the nucleoid, but also a timing device with an important role in the co-ordination of chromosome segregation and cell division.
2009-07-01 | E-MEXP-2133 | biostudies-arrayexpress
Project description:In Escherichia coli crosstalk between DNA supercoiling, nucleoid-associated proteins and major RNA polymerase σ initiation factors regulates growth phase-dependent gene transcription. We show that the highly conserved spatial ordering of relevant genes along the chromosomal replichores largely corresponds both to their temporal expression patterns during growth and to an inferred gradient of DNA superhelical density from the origin to the terminus. Genes implicated in similar functions are related mainly in trans across the chromosomal replichores, whereas DNA-binding transcriptional regulators interact predominantly with targets in cis along the replichores. We also demonstrate that macrodomains (the individual structural partitions of the chromosome) are regulated differently. We infer that spatial and temporal variation of DNA superhelicity during the growth cycle coordinates oxygen and nutrient availability with global chromosome structure, thus providing a mechanistic insight into how the organization of a complete bacterial chromosome encodes a spatiotemporal program integrating DNA replication and global gene expression.
2017-01-01 | GSE65244 | GEO
Project description:Paper abstract : The Escherichia coli SMC complex, MukBEF, interacts with the ParC subunit of topoisomerase IV (TopoIV), consistent with sequential roles in chromosome unlinking and segregation. Although clusters of MukBEF molecules are normally associated with the chromosome replication origin region (ori), we demonstrate their association with the replication termination region (ter), which is enhanced when ATP hydrolysis by MukB is impaired. We show that MukBEF interacts in vivo and in vitro with MatP, which binds matS sites in ter. The MatP-MukBEF interaction limits the stable association of MukBEF complexes with ter and the availability of functional TopoIV during decatenation of sister ters. The MukBEF-TopoIV interaction is influenced by the nucleotide state of MukBEF. The combined action of MukBEF and MatP helps position MukBEF clusters in relation to the chromosome, thereby, influencing chromosome organization and segregation. Finally, we demonstrate that the regulated sequential action of TopoIV and MukBEF promotes chromosome decatenation and segregation.
2016-01-28 | GSE67221 | GEO
Project description:C-di-GMP is a bacterial second messenger that regulates diverse processes in response to environmental or cellular cues. The nucleoid-associated protein (NAP) CdbA in Myxococcus xanthus binds DNA and c-di-GMP in a mutually exclusive manner in vitro. CdbA is essential for viability, and CdbA depletion causes defects in chromosome organization, leading to a block in cell division and, ultimately, cell death. Most NAPs are not essential; therefore, to explore the paradoxical cdbA essentiality, we isolated suppressor mutations that restored cell viability without CdbA. Most mutations mapped to cdbS, which encodes a stand-alone c-di-GMP binding PilZ domain protein, and caused loss-of-function of cdbS. Cells lacking CdbA and CdbS or only CdbS were fully viable and had no defects in chromosome organization. CdbA depletion caused post-transcriptional upregulation of CdbS accumulation, and this CdbS over-accumulation was required and sufficient to disrupt chromosome organization and, ultimately, cause cell death. CdbA depletion also caused increased accumulation of CsdK1 and CsdK2, two unusual PilZ-DnaK chaperones. During CdbA depletion, CsdK1 and CsdK2, in turn, stabilized CdbS, thereby enabling its increased accumulation and toxicity. CdbS accumulation also increased in response to heat stress at 37°C in a CsdK1- and CsdK2-dependent manner, possibly also involving an increased cellular c-di-GMP concentration, causing disrupted chromosome organization and accelerated cell death. Thus, increased CdbS accumulation caused by either CdbA depletion or heat stress results in disrupted chromosome organization and cell death. Collectively, our results suggest that the CdbA/CsdK1/CsdK2/CdbS system represents a new system for regulated cell death.
2023-05-24 | PXD041344 | Pride
Project description:Nucleoid remodeling facilitated by DNA supercoiling results in changes in nucleoid configuration and involves nucleoid-associated proteins (NAPs) and structural maintenance of chromosomes (SMC) proteins among others. Changes in nucleoid configurations regulated by NAPs are synchronized with cellular adaptation and influence the simultaneous expression of several genes. HU, a ubiquitous bacterial histone-like protein, is among the most conserved and abundant NAPs in eubacteria. In Escherichia coli, HU forms dimers by HUα self-association (HUαα) or by HUα-HUβ interactions (HUαβ). HUα is mostly expressed during lag and early exponential growth phase and HUβ is expressed only during the later exponential and stationary phase, pointing to distinct HUαα/DNA and HUαβ/DNA packaging of the nucleoid in regulating expression patterns during growth and stasis. Mutations or the deletion of HU transform the E. coli nucleoid to a different form and alter overall transcription program; thus, HU interactions with DNA directly affect global gene regulation. Recently, analysis of high-resolution contact maps of the E. coli nucleoid revealed an important role of HU to promote long-range DNA-DNA contacts within the nucleoid. Yet, the molecular connections between HU-DNA interactions and changes in nucleoid architecture that regulate gene expression globally remain unknown. Here, we explored the higher-order E. coli nucleoid organization by soft x-ray tomography (SXT) and revealed an effect of HU surface charges in overall nucleoid organization and rearrangements. We also studied global transcription by next-generation RNA sequencing (RNA-Seq) and found a link between nucleoid rearrangement and changes in global transcription. To determine the functional relationships of observed nucleoid rearrangement and HU-DNA interactions, we also characterized the overall organization of HU nucleoprotein complexes in solution by small angle x-ray scattering (SAXS). We found that HUαα-mediated DNA networks are different at different ionic strengths and pHs. By means of macromolecular crystallography, we additionally elucidate HUαα dependent molecular switches that modulate DNA networking. This integrative structural study explains how HUαα regulates dynamic transformations of the nucleoid by DNA bridging to control nucleoid rearrangement and global gene regulation.
2020-04-01 | GSE134667 | GEO
Project description:Plastids contain multiple copies of the plastid chromosome, folded together with proteins and RNA into nucleoids. The degree to which components of the plastid gene expression and protein biogenesis machineries are nucleoid associated, and the factors involved in plastid DNA organization, repair, and replication, are poorly understood. To provide a conceptual framework for nucleoid function, we characterized the proteomes of highly enriched nucleoid fractions of proplastids and mature chloroplasts isolated from the maize (Zea mays) leaf base and tip, respectively, using mass spectrometry. Quantitative comparisons with proteomes of unfractionated proplastids and chloroplasts facilitated the determination of nucleoid-enriched proteins. This nucleoid-enriched proteome included proteins involved in DNA replication, organization, and repair as well as transcription, mRNA processing, splicing, and editing. Many proteins of unknown function, including pentatricopeptide repeat (PPR), tetratricopeptide repeat (TPR), DnaJ, and mitochondrial transcription factor (mTERF) domain proteins, were identified. Strikingly, 70S ribosome and ribosome assembly factors were strongly overrepresented in nucleoid fractions, but protein chaperones were not. Our analysis strongly suggests that mRNA processing, splicing, and editing, as well as ribosome assembly, take place in association with the nucleoid, suggesting that these processes occur cotranscriptionally. The plastid developmental state did not dramatically change the nucleoid-enriched proteome but did quantitatively shift the predominating function from RNA metabolism in undeveloped plastids to translation and homeostasis in chloroplasts. This study extends the known maize plastid proteome by hundreds of proteins, including more than 40 PPR and mTERF domain proteins, and provides a resource for targeted studies on plastid gene expression. Details of protein identification and annotation are provided in the Plant Proteome Database.
2023-09-28 | PXD045331 | Pride