DNA Supercoiling-Dependent Gene Regulation in
            <i>Chlamydia</i>

Niehus, Eike; Cheng, Emily YiQin; Tan, Ming

doi:10.1128/jb.01413-08

Cited by 11 publications

(50 citation statements)

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“…Early genes are transcribed as soon as 1 h after infection, but the majority of chlamydial genes are not transcribed until mid times in the developmental cycle (2). We have proposed that the promoters of mid genes may be activated by the increased DNA supercoiling levels that we have measured during mid cycle (17). Furthermore, we have shown that representative mid-cycle promoters are transcribed at higher levels from more supercoiled templates in vitro (17), but we do not know if DNA supercoiling is a general mechanism for the activation of mid genes.…”

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confidence: 95%

“…supercoiling-sensitivity transcription assay to test promoter activity at different supercoiling levels using plasmid topoisomers that differ only in superhelical density (17). We tested promoters for three T3S operons that are first expressed at mid times in the chlamydial developmental cycle (cdsC, fliF, and incA) and another three T3S operons that are not transcribed until late time points (cdsJ, cdsU, and scc2) (2,9,24).…”

Section: Vol 192 2010mentioning

confidence: 99%

“…We also tested the promoter for the CT863 operon as a putative early T3S promoter based on detection of the CT863 transcript as early as 1.5 h postinfection (24). We cloned each T3S promoter on a transcription plasmid and generated a panel of topoisomers for each plasmid over a range of superhelical densities () from 0 (completely relaxed) to ϾϪ0.08 (highly negatively supercoiled) (20) to encompass the physiologic range of supercoiling (Ϫ0.028 to Ϫ0.077) that we have measured in Chlamydia (17). Four of the seven T3S promoters tested were transcribed in a supercoiling-responsive manner (Fig.…”

Section: Vol 192 2010mentioning

confidence: 99%

“…A subset is transcribed by the major chlamydial RNA polymerase, 66 RNA polymerase, while another group of late genes is regulated by an alternative form of RNA polymerase containing 28 instead of 66 (34,36). While the mechanism that regulates the 66 -dependent late genes has not been defined, it does not appear to involve DNA supercoiling since promoters for these genes were insensitive to changes in DNA supercoiling (17).…”

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Promoters forChlamydiaType III Secretion Genes Show a Differential Response to DNA Supercoiling That Correlates with Temporal Expression Pattern

Case¹,

Peterson²,

Tan

2010

J Bacteriol

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Type III secretion (T3S) is important for the establishment and maintenance of a chlamydial infection. The genes encoding T3S components in Chlamydia are transcribed as separate temporal classes, but the mechanisms that regulate the timing of their expression are not understood. In this study, we demonstrate that promoters for 10 predicted T3S transcriptional units are each transcribed in vitro by the major form of chlamydial RNA polymerase but not by an alternative form of RNA polymerase containing 28 . Since changes in DNA supercoiling during chlamydial development have been proposed as a mechanism for temporal gene regulation, we examined the in vitro response of T3S promoters to altered superhelical density. Promoters for three T3S genes that are upregulated at mid times were activated in response to increased DNA supercoiling. In contrast, promoters for three late T3S genes were not sensitive to changes in superhelical density. This differential response to changes in DNA topology is similar to the pattern that has been reported for representative mid and late chlamydial genes that are unrelated to the T3S system. Based on these results, we propose that the temporal expression of T3S genes in Chlamydia is controlled by general mechanisms that regulate 66 -dependent gene expression during the developmental cycle. Our results are consistent with a model in which T3S genes that are upregulated in mid cycle are activated together with other mid genes in response to increased DNA supercoiling.

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confidence: 95%

Section: Vol 192 2010mentioning

confidence: 99%

Section: Vol 192 2010mentioning

confidence: 99%

mentioning

confidence: 99%

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Promoters forChlamydiaType III Secretion Genes Show a Differential Response to DNA Supercoiling That Correlates with Temporal Expression Pattern

Case¹,

Peterson²,

Tan

2010

J Bacteriol

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“…Experiments with many pathogens involved in a wide variety of infections have shown that these infectionrelevant signals modulate the supercoiling of bacterial DNA, providing a background regulatory influence upon which the dedicated gene regulatory proteins operate. Examples have come from studies in Bordetella pertussis (Graeff-Wohlleben et al 1995), Campylobacter jejuni (Dedieu et al 2002), Chlamydia (Niehus et al 2008), Dickeya dadantii (Hérault et al 2014), E. coli (Beltrametti et al 1999;Sánchez-Céspedes et al 2015), Helicobacter pylori (Ye et al 2007), Salmonella spp. (Bang et al 2002;Galán and Curtiss 1990;Leclerc et al 1998;Ó Cróinín et al 2006;Webber et al 2013), Shigella flexneri (Dorman et al 1990), Vibrio cholerae (Parsot and Mekalanos 1992), Staphylococcus aureus (Fournier and Klier 2004;Schröder et al 2014;Sheehan et al 1992) and Yersinia enterocolitica (Rohde et al 1994).…”

Section: Dna Supercoiling Bacterial Evolution and Pathogenesismentioning

confidence: 99%

DNA supercoiling is a fundamental regulatory principle in the control of bacterial gene expression

Dorman

2016

Biophys Rev

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Although it has become routine to consider DNA in terms of its role as a carrier of genetic information, it is also an important contributor to the control of gene expression. This regulatory principle arises from its structural properties. DNA is maintained in an underwound state in most bacterial cells and this has important implications both for DNA storage in the nucleoid and for the expression of genetic information. Underwinding of the DNA through reduction in its linking number potentially imparts energy to the duplex that is available to drive DNA transactions, such as transcription, replication and recombination. The topological state of DNA also influences its affinity for some DNA binding proteins, especially in DNA sequences that have a high A + T base content. The underwinding of DNA by the ATP-dependent topoisomerase DNA gyrase creates a continuum between metabolic flux, DNA topology and gene expression that underpins the global response of the genome to changes in the intracellular and external environments. These connections describe a fundamental and generalised mechanism affecting global gene expression that underlies the specific control of transcription operating through conventional transcription factors. This mechanism also provides a basal level of control for genes acquired by horizontal DNA transfer, assisting microbial evolution, including the evolution of pathogenic bacteria.

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DNA supercoiling: A regulatory signal for the λ repressor

Ding¹,

Manzo²,

Fulcrand

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Topoisomerases, polymerases, and the chirality introduced by the binding of histones or nucleoid-associated proteins affect DNA supercoiling in vivo. However, supercoiling is not just a by-product of DNA metabolism. Supercoiling is an indicator of cell health, it modifies the accessibility of chromatin, and coordinates the transcription of genes. This suggests that regulatory, proteinmediated loops in DNA may sense supercoiling of the genome in which they are embedded. The λ repressor (CI) maintains the quiescent (lysogenic) transcriptome of bacteriophage λ in infected Escherichia coli. CI-mediated looping prevents overexpression of the repressor protein to preserve sensitivity to conditions that trigger virulence (lysis). Experiments were performed to assess how well the CI-mediated DNA loop traps superhelicity and determine whether supercoiling enhances CI-mediated DNA looping. CI oligomers partitioned plasmids into topological domains and prevented the passage of supercoiling between them. Furthermore, in single DNA molecules stretched and twisted with magnetic tweezers, levels of superhelical density confined in CI-mediated DNA loops ranged from −15% or +11%. Finally, in DNA under tensions that may occur in vivo, supercoiling lowered the free energy of loop formation and was essential for DNA looping. Supercoiling-enhanced looping can influence the maintenance of lysogeny in the λ repressor system; it can encode sensitivity to the energy level of the cell and creates independent topological domains of distinct superhelical density.DNA looping | DNA supercoiling | bacteriophage λ repressor | magnetic tweezer | transcription

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DNA Supercoiling-Dependent Gene Regulation in Chlamydia

Cited by 11 publications

References 0 publications

Promoters forChlamydiaType III Secretion Genes Show a Differential Response to DNA Supercoiling That Correlates with Temporal Expression Pattern

Promoters forChlamydiaType III Secretion Genes Show a Differential Response to DNA Supercoiling That Correlates with Temporal Expression Pattern

DNA supercoiling is a fundamental regulatory principle in the control of bacterial gene expression

DNA supercoiling: A regulatory signal for the λ repressor

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