Observation of binding and polymerization of Fur repressor onto operator-containing DNA with electron and atomic force microscopes.

Cam, Eric Le; Frechon, D; Barray, Martine; Fourcade, A; Delain, Etienne

doi:10.1073/pnas.91.25.11816

Cited by 75 publications

(32 citation statements)

References 31 publications

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“…The physiological relevance of oligomeric Fur binding at high protein concentrations is not certain. Whereas the dimeric Fur can oligomerize both in the presence and absence of DNA3839, Streptomyces dimeric Zur in our study did not form oligomers in the absence of DNA. In the case of X. campestris Zur7, the binding site upstream of the putative efflux gene showed a different sequence motif distant from the Zur-box consensus found in zinc-uptake genes.…”

Section: Discussioncontrasting

confidence: 64%

Zinc-dependent regulation of zinc import and export genes by Zur

et al. 2017

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In most bacteria, zinc depletion is sensed by Zur, whereas the surplus is sensed by different regulators to achieve zinc homeostasis. Here we present evidence that zinc-bound Zur not only represses genes for zinc acquisition but also induces the zitB gene encoding a zinc exporter in Streptomyces coelicolor, a model actinobacteria. Zinc-dependent gene regulation by Zur occurs in two phases. At sub-femtomolar zinc concentrations (phase I), dimeric Zur binds to the Zur-box motif immediately upstream of the zitB promoter, resulting in low zitB expression. At the same time, Zur represses genes for zinc uptake. At micromolar zinc concentrations (phase II), oligomeric Zur binding with footprint expansion upward from the Zur box results in high zitB induction. Our findings reveal a mode of zinc-dependent gene activation that uses a single metalloregulator to control genes for both uptake and export over a wide range of zinc concentrations.

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Section: Discussioncontrasting

confidence: 64%

Zinc-dependent regulation of zinc import and export genes by Zur

et al. 2017

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“…It has been reported that Fur may have more than one binding site at a given promoter, and these often constitute a primary high‐affinity site and a secondary proximal lower affinity site (de Lorenzo et al ., 1987; Brickman et al ., 1990; Tardat and Touati, 1993; Ochsner et al ., 1995; Chai et al ., 1998). Footprinting analyses have also shown that, at higher concentrations of protein, the protected regions can extend from the specific binding sites over the DNA (Frechon and Le Cam, 1994;Escolar et al ., 2000), and visualization of these complexes demonstrated that the protein polymerizes on its binding site through Fur–Fur interactions wrapping helically around the DNA (Frechon and Le Cam, 1994; Le Cam et al ., 1994). In addition, it has been shown that, in E. coli , Fur binding does not bend DNA, both through visualization of rigid Fur–DNA complexes (Le Cam et al ., 1994) and by circular permutation experiments (de Lorenzo et al ., 1988).…”

Section: Discussionmentioning

confidence: 99%

“…Footprinting analyses have also shown that, at higher concentrations of protein, the protected regions can extend from the specific binding sites over the DNA (Frechon and Le Cam, 1994;Escolar et al ., 2000), and visualization of these complexes demonstrated that the protein polymerizes on its binding site through Fur–Fur interactions wrapping helically around the DNA (Frechon and Le Cam, 1994; Le Cam et al ., 1994). In addition, it has been shown that, in E. coli , Fur binding does not bend DNA, both through visualization of rigid Fur–DNA complexes (Le Cam et al ., 1994) and by circular permutation experiments (de Lorenzo et al ., 1988). In view of these reports, the pattern of DNase I protection and hypersensitivity observed on the pfr promoter DNA of H. pylori suggests a different mechanism of binding.…”

Section: Discussionmentioning

confidence: 99%

The Fur repressor controls transcription of iron‐activated and ‐repressed genes in Helicobacter pylori

Delany¹,

Spohn²,

Rappuoli³

et al. 2001

Molecular Microbiology

177

242

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“…Fur is able to fine-tune the transcription of the mrkHI operon in response to the presence of iron (10). It is known that the ␣-CTD of RNAP interacts with UP elements in the minor groove of DNA (44,49) whereas Fur binds to the major DNA groove of the Fur box (50). It is therefore possible that the regulatory region of the mrkHI operon is able to accommodate both the ␣-CTD of RNAP and Fur.…”

Section: Figmentioning

confidence: 99%

Positive Autoregulation ofmrkHIby the Cyclic Di-GMP-Dependent MrkH Protein in the Biofilm Regulatory Circuit of Klebsiella pneumoniae

Tan¹,

Wilksch²,

Hocking³

et al. 2015

J. Bacteriol.

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Klebsiella pneumoniae is an important cause of nosocomial infections, primarily through the formation of surface-associated biofilms to promote microbial colonization on host tissues. Expression of type 3 fimbriae by K. pneumoniae facilitates surface adherence, a process strongly activated by the cyclic di-GMP (c-di-GMP)-dependent transcriptional activator MrkH. In this study, we demonstrated the critical importance of MrkH in facilitating K. pneumoniae attachment on a variety of medically relevant materials and demonstrated the mechanism by which bacteria activate expression of type 3 fimbriae to colonize these materials. Sequence analysis revealed a putative MrkH recognition DNA sequence ("MrkH box"; TATCAA) located in the regulatory region of the mrkHI operon. Mutational analysis, electrophoretic mobility shift assay, and quantitative PCR experiments demonstrated that MrkH binds to the cognate DNA sequence to autoregulate mrkHI expression in a c-di-GMP-dependent manner. A half-turn deletion, but not a full-turn deletion, between the MrkH box and the ؊35 promoter element rendered MrkH ineffective in activating mrkHI expression, implying that a direct interaction between MrkH and RNA polymerase exists. In vivo analyses showed that residues L260, R265, N268, C269, E273, and I275 in the C-terminal domain of the RNA polymerase ␣ subunit are involved in the positive control of mrkHI expression by MrkH and revealed the regions of MrkH required for DNA binding and transcriptional activation. Taken together, the data suggest a model whereby c-di-GMP-dependent MrkH recruits RNA polymerase to the mrkHI promoter to autoactivate mrkH expression. Increased MrkH production subsequently drives mrkABCDF expression when activated by c-di-GMP, leading to biosynthesis of type 3 fimbriae and biofilm formation. IMPORTANCEBacterial biofilms can cause persistent infections that are refractory to antimicrobial treatments. This study investigated how a commonly encountered hospital-acquired pathogen, Klebsiella pneumoniae, controls the expression of MrkH, the principal regulator of type 3 fimbriae and biofilm formation. We discovered a regulatory circuit whereby MrkH acts as a c-di-GMP-dependent transcriptional activator of both the gene cluster of type 3 fimbriae and the mrkHI operon. In this positive-feedback loop, whereby MrkH activates its own production, K. pneumoniae has evolved a mechanism to ensure rapid MrkH production, expression of type 3 fimbriae, and subsequent biofilm formation under favorable conditions. Deciphering the molecular mechanisms of biofilm formation by bacterial pathogens is important for the development of innovative treatment strategies for biofilm infections. Biofilm-related infections substantially contribute to patient morbidity and place a significant burden on health care systems. The evolution of high-technology medicine such as intensive and invasive hospital care practices and immunosuppressive therapy and the emergence of multiply antibiotic-resistant organisms have contributed to the rise...

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Observation of binding and polymerization of Fur repressor onto operator-containing DNA with electron and atomic force microscopes.

Abstract: The

Cited by 75 publications

References 31 publications

Zinc-dependent regulation of zinc import and export genes by Zur

Zinc-dependent regulation of zinc import and export genes by Zur

The Fur repressor controls transcription of iron‐activated and ‐repressed genes in Helicobacter pylori

Positive Autoregulation ofmrkHIby the Cyclic Di-GMP-Dependent MrkH Protein in the Biofilm Regulatory Circuit of Klebsiella pneumoniae

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