Synthetic curved DNA sequences can act as transcriptional activators in Escherichia coli.

Bracco, Laurent; Kotlarz, Denise; Kolb, Annie; Diekmann, Stephan; Buc, Henri

doi:10.1002/j.1460-2075.1989.tb08615.x

Cited by 343 publications

(204 citation statements)

References 39 publications

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“…However, in these bandshift studies the maximum preference for any curved sequence tested, including the DRE, was only a few-fold greater than for generic DNA. This is consistent with previous reports that H-NS shows a binding preference for curved DNA; these other studies also used similar bandshift assays, and all demonstrated less than a 10-fold preference for any curved DNA fragment compared with generic DNA (11)(12)(13)(14)18). In apparent contrast to the bandshift experiments, filter retention experiments failed to reveal any major binding preference of H-NS for curved DNA or for the DRE.…”

Section: Discussionsupporting

confidence: 90%

“…H-NS has previously been shown, by bandshift studies, to exhibit a binding preference for intrinsically curved DNA elements generated by phased A tracts (11)(12)(13). We have shown here that H-NS has a similar binding preference for non-A tract curves (GC curves).…”

Section: Discussionsupporting

confidence: 52%

“…How does H-NS influence transcription at only a subset of promoters? Part of the explanation may come from the observation that H-NS exhibits a binding preference for certain intrinsically curved DNA sequences in vitro (11)(12)(13)(14) and that, at least at some promoters, curved DNA elements are required for H-NS action in vivo (13). Indeed, it may be that curved DNA sequence elements are required for the action of H-NS at all promoters (15)(16)(17).…”

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confidence: 99%

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DNA Binding Is Not Sufficient for H-NS-mediated Repression ofproU Expression

Jordi¹,

Fielder

Burns

et al. 1997

Journal of Biological Chemistry

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H-NS is a major component of bacterial chromatin and influences the expression of many genes. H-NS has beenshown to exhibit a binding preference for certain ATrich curved DNA elements in vitro. In this study we have addressed the factors that determine the specificity of H-NS action in vitro and in vivo. In bandshift studies, H-NS showed a slight binding preference for all curved sequences tested whether GC-based or AT-based; the specific architecture of the curve also influenced H-NS binding. In filter retention assays little difference in affinity could be detected for any sequence tested, including the downstream regulatory element (DRE) a downstream curved DNA element required for H-NS to repress transcription of the Salmonella typhimurium proU operon in vivo. A K d of 1-2 M was estimated for binding of H-NS to each of these sequences. In vivo, the distance between the proU promoter and the DRE, their relative orientations on the face of the DNA helix, and translation of the DRE had no major effect on proU regulation. None of the synthetic curved sequences tested could functionally replace the DRE in vivo. These data show that differential binding to curved DNA cannot account for the specificity of H-NS action in vivo. Furthermore, binding of H-NS to DNA per se is insufficient to repress the proU promoter. Thus, the DRE does not simply act as an H-NS binding site but must have a more specific role in mediating H-NS regulation of proU transcription.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 52%

mentioning

confidence: 99%

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DNA Binding Is Not Sufficient for H-NS-mediated Repression ofproU Expression

Jordi¹,

Fielder

Burns

et al. 1997

Journal of Biological Chemistry

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“…The major nucleoid-associated protein HU has been shown to constrain negative supercoils by compacting the DNA into nucleosome-like structures (Rouviè re-Yaniv et al, 1979;Broyles and Pettijohn, 1986). Another important protein implicated in the structure of the E. coli nucleoid is H-NS (Varshavsky et al, 1977;Spassky et al, 1984;Higgins et al, 1988; reviewed by Ussery et al, 1994), which binds preferentially to curved DNA (Bracco et al, 1989;Yamada et al, 1990;Zuber et al, 1994) and, when overproduced, results in the condensation of bacterial chromosome (Spurio et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

FIS modulates growth phase‐dependent topological transitions of DNA in Escherichia coli

Schneider

Travers

Muskhelishvili

1997

Molecular Microbiology

117

104

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SummaryThe Escherichia coli DNA-binding protein FIS serves as a DNA architectural factor in two unrelated enzymatic reactions, the site-specific inversion of DNA and transcriptional activation of stable RNA promoters. In both these processes, FIS facilitates the assembly and dynamic transitions of two structurally distinct nucleoprotein complexes. We have proposed previously that, in these systems, FIS stabilizes writhed DNA microloops by binding at multiple helically phased sites in DNA. However, FIS also binds and bends DNA at many non-specific sites and, at its maximum levels in the early exponential phase, FIS could potentially occupy a considerable part of the E. coli chromosome. Here, we show that fis affects growth phase-specific alterations in the supercoiling level of DNA. Expression of fis accelerates the accumulation of moderately supercoiled plasmids in stationary phase, which are stabilized by FIS after nutritional shift-up. In accordance with such a function, FIS modulates the relaxing and supercoiling activities of topoisomerases in vitro in a way that keeps DNA in a moderately supercoiled state. Our results suggest that the primary role of FIS is to modulate chromosomal dynamics during bacterial growth.

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“…A+T-rich upstream DNA displaying curvature can sometimes replace a transcriptional activator (e.g. see [23][24][25]. However, in some cases it has not been shown that the position of the bend and the position of the sequences which increase transcription are the same.…”

Section: Introductionmentioning

confidence: 99%

Localization of the intrinsically bent DNA region upstream of theE.coli rrnBP1 promoter

Gaál¹,

Lin²,

Estrem³

et al. 1994

Nucl Acids Res

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DNA sequences upstream of the rrnB P1 core promoter (-10, -35 region) increase transcription more than 300-fold In vivo and in vitro. This stimulation results from a cis-acting DNA sequence, the UP element, which interacts directly with the alpha subunit of RNA polymerase, increasing transcription about 30-fold, and from a positively acting transcription factor, FIS, which increases expression another 10-fold. A DNA region exhibiting a high degree of intrinsic curvature has been observed upstream of the rrnB P1 core promoter and has thus been often cited as an example of the effect of bending on transcription. However, the precise position of the curvature has not been determined. We address here whether this bend is in fact related to activation of rRNA transcription. Electrophoretic analyses were used to localize the major bend in the rrnB P1 upstream region to position approximately -100 with respect to the transcription initiation site. Since most of the effect of upstream sequences on transcription results from DNA between the -35 hexamer and position -88, i.e. downstream of the bend center, these studies indicate that the curvature leading to the unusual electrophoretic behavior of the upstream region does not play a major role in activation of rRNA transcription. Minor deviations from normal electrophoretic behavior were associated with the region just upstream of the -35 hexamer and could conceivably influence interactions between the UP element and the alpha subunit of RNA polymerase.

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Synthetic curved DNA sequences can act as transcriptional activators in Escherichia coli.

Cited by 343 publications

References 39 publications

DNA Binding Is Not Sufficient for H-NS-mediated Repression ofproU Expression

DNA Binding Is Not Sufficient for H-NS-mediated Repression ofproU Expression

FIS modulates growth phase‐dependent topological transitions of DNA in Escherichia coli

Localization of the intrinsically bent DNA region upstream of theE.coli rrnBP1 promoter

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