DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Odsbu, Ingvild; Skarstad, Kirsten

doi:10.1099/mic.0.075051-0

Cited by 42 publications

(37 citation statements)

References 73 publications

(90 reference statements)

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“…Similar observations have been previously reported for I-SceI181931. This regression of sister chromatids over a large distance is correlated with the re-merging of segregating nucleoids.…”

Section: Discussionsupporting

confidence: 89%

“…3c,d). This phenomenon was observed 10±10 min after MMC addition and, as previously described, was dependent on both the RecA and RecN proteins31. Regression of sister foci was observed a few minutes following nucleoid merging (Fig.…”

Section: Resultssupporting

confidence: 80%

“…Interestingly, a different activity has been observed for RecN in Caulobacter cresentus and E. coli . It has been reported that RecN in this system is implicated in nucleoid dynamics following DSB repair3031.…”

mentioning

confidence: 98%

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Management of E. coli sister chromatid cohesion in response to genotoxic stress

et al. 2017

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Aberrant DNA replication is a major source of the mutations and chromosomal rearrangements associated with pathological disorders. In bacteria, several different DNA lesions are repaired by homologous recombination, a process that involves sister chromatid pairing. Previous work in Escherichia coli has demonstrated that sister chromatid interactions (SCIs) mediated by topological links termed precatenanes, are controlled by topoisomerase IV. In the present work, we demonstrate that during the repair of mitomycin C-induced lesions, topological links are rapidly substituted by an SOS-induced sister chromatid cohesion process involving the RecN protein. The loss of SCIs and viability defects observed in the absence of RecN were compensated by alterations in topoisomerase IV, suggesting that the main role of RecN during DNA repair is to promote contacts between sister chromatids. RecN also modulates whole chromosome organization and RecA dynamics suggesting that SCIs significantly contribute to the repair of DNA double-strand breaks (DSBs).

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“…Similar observations have been previously reported for I-SceI181931. This regression of sister chromatids over a large distance is correlated with the re-merging of segregating nucleoids.…”

Section: Discussionsupporting

confidence: 89%

Section: Resultssupporting

confidence: 80%

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Management of E. coli sister chromatid cohesion in response to genotoxic stress

et al. 2017

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“…The nucleoid occupies the central part of the bacterial cell (8), and its shape is dependent on a variety of factors, such as environmental conditions or genetic mutations (7,(10)(11)(12)(13). For example, significant nucleoid compaction occurs after exposure of Escherichia coli to UV light, due to a global reorganization in response to DNA damage and the activation of the SOS response (12,13).…”

mentioning

confidence: 99%

Lack of the H-NS Protein Results in Extended and Aberrantly Positioned DNA during Chromosome Replication and Segregation in Escherichia coli

2016

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The architectural protein H-NS binds nonspecifically to hundreds of sites throughout the chromosome and can multimerize to stiffen segments of DNA as well as to form DNA-protein-DNA bridges. H-NS has been suggested to contribute to the orderly folding of the Escherichia coli chromosome in the highly compacted nucleoid. In this study, we investigated the positioning and dynamics of the origins, the replisomes, and the SeqA structures trailing the replication forks in cells lacking the H-NS protein.In H-NS mutant cells, foci of SeqA, replisomes, and origins were irregularly positioned in the cell. Further analysis showed that the average distance between the SeqA structures and the replisome was increased by ϳ100 nm compared to that in wild-type cells, whereas the colocalization of SeqA-bound sister DNA behind replication forks was not affected. This result may suggest that H-NS contributes to the folding of DNA along adjacent segments. H-NS mutant cells were found to be incapable of adopting the distinct and condensed nucleoid structures characteristic of E. coli cells growing rapidly in rich medium. It appears as if H-NS mutant cells adopt a "slow-growth" type of chromosome organization under nutrient-rich conditions, which leads to a decreased cellular DNA content. IMPORTANCE It is not fully understood how and to what extent nucleoid-associated proteins contribute to chromosome folding and organization during replication and segregation in Escherichia coli. In this work, we find in vivo indications that cells lacking the nucleoid-associated protein H-NS have a lower degree of DNA condensation than wild-type cells. Our work suggests that H-NS is in-volved in condensing the DNA along adjacent segments on the chromosome and is not likely to tether newly replicated strands of sister DNA. We also find indications that H-NS is required for rapid growth with high DNA content and for the formation of a highly condensed nucleoid structure under such conditions. A cross all domains of life, it is crucial that genomes are structurally organized in a way that compacts DNA to fit inside the confined space of a cell and at the same time allows for interaction with key proteins performing replication, transcription, recombination, and repair (1-7). Unlike eukaryotic cells, bacterial cells do not possess an envelope-enclosed organelle for storage and handling of genomic DNA. The DNA is instead organized into compact bodies called nucleoids (3)(4)(5)8). These nucleoids are highly complex, and the underlying organizational mechanisms appear to be remarkably similar to that of eukaryotic cells (3, 9). The nucleoid occupies the central part of the bacterial cell (8), and its shape is dependent on a variety of factors, such as environmental conditions or genetic mutations (7, 10-13). For example, significant nucleoid compaction occurs after exposure of Escherichia coli to UV light, due to a global reorganization in response to DNA damage and the activation of the SOS response (12, 13).Certain types of proteins, called nucle...

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“…While these genes are not identical, their products, RecR and RecX, both interact with the protein RecA [43]. RecA is responsible for repairing DNA breaks through homologous recombination, the reactivation of a stalled replication fork, and initiation of the SOS response [44].…”

Section: Discussionmentioning

confidence: 99%

Genetic Expression Profile Analysis of the Temporal Inhibition of Quercetin and Naringenin on Lactobacillus Rhamnosus GG

Liu¹,

Firrman²

2016

J Prob Health

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Plant polyphenols quercetin and naringenin are considered healthy dietary compounds; however, little is known of their effect on the probiotic Lactobacillus rhamnosus GG (LGG). In this study it was discovered that both quercetin and naringenin produced temporary inhibition of LGG growth, particularly at 8 hours post inoculation, with LGG eventually recovering from this suppression. The observed growth inhibition was regarded as a phenotypic response of LGG to the polyphenols; we hypothesized that the subsequent recovery was due to unknown, underlying genetic factors. The molecular response of LGG to quercetin and naringenin was determined through RNA analysis using the Helicos single molecule sequencing platform. The expression profiles of LGG grown in the presence of either quercetin or naringenin were divergent from each other, with only a few similarities, indicating that these polyphenols inhibit growth through separate mechanisms.LGG treated with quercetin demonstrated upregulation of genes associated with DNA repair and transcriptional regulation, and a decrease in expression of genes involved in metabolism and protein movement through the cell wall.LGG treated with naringenin resulted in an increase of genes associated with metabolism, and a decrease in genes involved in stress response. Results from this study demonstrate that there is a clear interaction between the polyphenols quercetin and naringenin and the probiotic LGG. The RNA expression analysis provides unique insight into the molecular response of LGG to quercetin and naringenin, revealing an identifiable pattern of gene expression.

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DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Cited by 42 publications

References 73 publications

Management of E. coli sister chromatid cohesion in response to genotoxic stress

Management of E. coli sister chromatid cohesion in response to genotoxic stress

Lack of the H-NS Protein Results in Extended and Aberrantly Positioned DNA during Chromosome Replication and Segregation in Escherichia coli

Genetic Expression Profile Analysis of the Temporal Inhibition of Quercetin and Naringenin on Lactobacillus Rhamnosus GG

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