Condensation of nucleoid during environmental adaptation is regulated by dynamic HU interactions
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ABSTRACT:
PROVIDER: PRJNA556020 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR9732210_1.fastq.gz | Fastqsanger.gz | |||
| SRR9732210_2.fastq.gz | Fastqsanger.gz | |||
| SRR9732220_1.fastq.gz | Fastqsanger.gz | |||
| SRR9732220_2.fastq.gz | Fastqsanger.gz | |||
| SRR9732230_1.fastq.gz | Fastqsanger.gz |
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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:HU is a conserved prokaryotic nucleoid-associated protein known for its role in DNA binding and maintaining negative supercoils in DNA. HU also binds to a few RNAs but the natural targets are unknown. To understand the biology of HU interactions with RNA in Escherichia coli, potential HU-RNA in vivo complexes were immunoprecipitated and bound RNAs were examined by hybridization to whole-genome tiling arrays. We observed HU associations with rRNA, multiple tRNAs, a few sRNAs and a small, distinct set of mRNAs. More importantly, we also identified associations between HU and ten intragenic non-coding (nonc) RNAs, two of which are homologous to the annotated Bacterial Interspersed Mosaic Elements (BIME) and boxC elements; the other eight RNAs have not been annotated. We confirmed binding of HU to BIME RNA in vitro. Since HU and some unidentified RNAs have been implicated in the nucleoid structure, we explored an idea that HU, along with some or all of the nonc RNA species discovered here bind to BIME and/or boxC repeats to condense chromosomal DNA in a specific fashion. We propose that nonc RNAs may interact with both HU and DNA repeats to form ternary complexes, which are the anchoring points separating different chromosomal domains.
2012-12-07 | GSE28565 | GEO
Project description:Bacterial nucleoid remodeling dependent on conserved histone-like protein, HU is one of the determining factors in global gene regulation. By imaging of near-native, unlabeled E. coli cells by soft X-ray tomography, we show that HU remodels nucleoids by promoting the formation of a dense condensed core surrounded by less condensed isolated domains. Nucleoid remodeling during cell growth and environmental adaptation correlate with pH and ionic strength controlled molecular switch that regulated HUαα dependent intermolecular DNA bundling. Through crystallographic and solution-based studies we show that these effects mechanistically rely on HUαα promiscuity in forming multiple electrostatically driven multimerization interfaces. Changes in DNA bundling consequently affects gene expression globally, likely by constrained DNA supercoiling. Taken together our findings unveil a critical function of HU-DNA interaction in nucleoid remodeling that may serve as a general microbial mechanism for transcriptional regulation to synchronize genetic responses during the cell cycle and adapt to changing environments.
| S-EPMC7283360 | biostudies-literature
Project description:The regulon of genes controlled by the HU nucleoid-associated proteins was examined in Salmonella enterica serovar Typhimurium (S. Typhimurium). DNA microarrays were used to detect the effect on the bacterial transcriptome of knockout mutations in the hupA, the hupB and in both the hupA and hupB genes. Distinct but overlapping patterns of gene expression were detected in the transcriptome at each time point for each of the three mutants, pointing to the existence of not one but three regulons of genes controlled by the HU proteins. Mutations in the hup genes altered the expression of regulatory and structural genes in both the SPI1 and the SPI2 pathogenicity islands. The hupA hupB double mutant was found to be defective in invasion of CACO2 and CHO epithelial cell lines and in its ability to survive in J774A.1 macrophage-like cells. The double mutant also had defective swarming activity and had a competitive fitness disadvantage compared to the wild type. In contrast, inactivation of just the hupB gene resulted in increased fitness and correlated with the up-regulation of members of the RpoS regulon in exponential phase cultures. Elimination of both the hupA and hupB genes resulted in strong down-regulation of the genes coding for the integration host factor, IHF, at all three time points.
2011-03-22 | GSE22860 | GEO
Project description:The physiological role of the various nucleoid-associated proteins in bacteria and HU in particular has been addressed in a number of studies but remains so far not fully understood. In this work, a genome-wide microarray hybridization approach, combined with in vivo genetic experimentation, has been performed in order to compare and evaluate the effect of HUalpha, HUbeta and HUalphabeta on the transcription of the Escherichia coli K12 genes as a function of growth phase. The histone-like protein HU is present in the E. coli cell under three dimeric forms (HUalphabeta, HUalpha2 and HUbeta2) in a ratio that varies with growth phase. The experimental protocol is designed to handle strain genotype and growth phase as independent variables. Keywords: genotype, growth phase
2009-01-01 | GSE11183 | GEO
Project description:The regulon of genes controlled by the HU nucleoid-associated proteins was examined in Salmonella enterica serovar Typhimurium (S. Typhimurium). DNA microarrays were used to detect the effect on the bacterial transcriptome of knockout mutations in the hupA, the hupB and in both the hupA and hupB genes. Distinct but overlapping patterns of gene expression were detected in the transcriptome at each time point for each of the three mutants, pointing to the existence of not one but three regulons of genes controlled by the HU proteins. Mutations in the hup genes altered the expression of regulatory and structural genes in both the SPI1 and the SPI2 pathogenicity islands. The hupA hupB double mutant was found to be defective in invasion of CACO2 and CHO epithelial cell lines and in its ability to survive in J774A.1 macrophage-like cells. The double mutant also had defective swarming activity and had a competitive fitness disadvantage compared to the wild type. In contrast, inactivation of just the hupB gene resulted in increased fitness and correlated with the up-regulation of members of the RpoS regulon in exponential phase cultures. Elimination of both the hupA and hupB genes resulted in strong down-regulation of the genes coding for the integration host factor, IHF, at all three time points. The effect of hupA and hupB single-deletions and hupA and hupB double-deletion on S. Typhimurium gene expression during growth in LB was analysed at 3 different time points (1, 4 and 6 hours post-inoculation). Between two and three biological replicates, as well as technical replicates, were performed for each mutant and time point. For this study, we used Salmonella genomic DNA as the comparator which also acted as the control for spot quality.
2011-03-22 | E-GEOD-22860 | biostudies-arrayexpress
Project description:IHF and HU are two heterodimeric nucleoid associated proteins (NAP) that belong to the same protein family but interact differently with the DNA. IHF is a sequence-specific DNA-binding protein that bends the DNA by over 160o. HU is the most conserved NAP which binds non-specifically to duplex DNA with a particular preference for targeting nicked and bent DNA. Despite their importance, the in-vivo interactions of the two proteins to the DNA remain to be described at a high resolution and on a genome-wide scale. Further, the effects of these proteins on gene expression on a global scale remain contentious. Finally, the contrast between the functions of the homo- and heterodimeric forms of these proteins deserves the attention of further study. Here we present a genome-scale study of HU- and IHF-binding to the E. coli K12 chromosome using ChIP-seq. We also perform microarray analysis of gene expression in single- and double-deletion mutants of each protein to identify their regulons. This data is for microarrays measuring gene expression changes in the various ihf mutants when compared to the wildtype.<br>
2011-11-30 | E-MEXP-3461 | biostudies-arrayexpress
Project description:Molecular mechanisms controlling functional bacterial chromosome (nucleoid) compaction and organization are surprisingly enigmatic but partly depend on conserved, histone-like proteins HUαα and HUαβ and their interactions that span the nanoscale and mesoscale from protein-DNA complexes to the bacterial chromosome and nucleoid structure. We determined the crystal structures of these chromosome-associated proteins in complex with native duplex DNA. Distinct DNA binding modes of HUαα and HUαβ elucidate fundamental features of bacterial chromosome packing that regulate gene transcription. By combining crystal structures with solution x-ray scattering results, we determined architectures of HU-DNA nucleoproteins in solution under near-physiological conditions. These macromolecular conformations and interactions result in contraction at the cellular level based on in vivo imaging of native unlabeled nucleoid by soft x-ray tomography upon HUβ and ectopic HUα38 expression. Structural characterization of charge-altered HUαα-DNA complexes reveals an HU molecular switch that is suitable for condensing nucleoid and reprogramming noninvasive Escherichia coli into an invasive form. Collective findings suggest that shifts between networking and cooperative and noncooperative DNA-dependent HU multimerization control DNA compaction and supercoiling independently of cellular topoisomerase activity. By integrating x-ray crystal structures, x-ray scattering, mutational tests, and x-ray imaging that span from protein-DNA complexes to the bacterial chromosome and nucleoid structure, we show that defined dynamic HU interaction networks can promote nucleoid reorganization and transcriptional regulation as efficient general microbial mechanisms to help synchronize genetic responses to cell cycle, changing environments, and pathogenesis.
| S-EPMC4966879 | biostudies-literature
Project description:As in Eukaryotes, bacterial genomes are not randomly folded. Bacterial genetic information is generally carried on a circular chromosome with a single origin of replication from which two replication forks proceed bidirectionaly towards the opposite terminus region. Here we investigate the higher-order architecture of the Escherichia coli genome, showing its partition into two structuraly distinct entities by a complex and intertwined network of contacts: the replication terminus (ter) region and the rest of the chromosome. Outside ter, the condensin MukBEF and the ubiquitous nucleoid-associated protein (NAP) HU promote DNA contacts in the megabase range. Within ter, the MatP protein prevents MukBEF activity and contacts are restricted to ~280 kb creating a domain with distinct structural properties. We also show how other NAPs contribute to nucleoid organization, such as H-NS that restricts short-range interactions. Combined, these results reveal the contributions of major, evolutionary conserved proteins in a bacterial chromosome organization.
2017-12-07 | GSE107301 | GEO
Project description:Hydroxyurea (HU) is toxic to Sulfolobus cells. To address the basis of the HU toxicity, we performed transcriptome analyses on untreated cells and cells following exposure to 5 mM HU for 4 hours.
2016-10-05 | GSE87612 | GEO