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  • 1
    Electronic Resource
    Electronic Resource
    The outer membrane protein, Antigen 43, mediates cell-to-cell interactions within Escherichia coli biofilms (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 37 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Transcription of the agn43 locus, which specifies an outer membrane protein of Escherichia coli, is regulated in a phase-variable fashion by the OxyR–DNA binding protein and Dam methylase. Despite its well-characterized regulation, the function of Ag43 has remained elusive until now. Previous studies indicated that Ag43 mediates autoaggregation of certain strains of E. coli in liquid culture. Given this phenotype, we examined the role of Ag43 in biofilm formation. Here, we report that Ag43 contributes to E. coli biofilm formation in glucose-minimal medium, but not in Luria–Bertani broth. In addition, we show that flagellar-mediated motility is required for biofilm formation in both rich and minimal environments. Altogether, our results suggest that E. coli uses both common and specific gene sets for the development of biofilms under various growth conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.02008.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Multicopy fim B gene expression in Escherichia coli: binding to inverted repeats in vivo, effect on fimA gene transcription and DNA inversion (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Transcription of fimA, the Escherichia coli gene encoding the type 1 fimbrial subunit protein, is driven by a promoter carried on a 314bp segment of invertible DNA. We have discovered that overexpression of fimB, one of the genes required for inversion of this DNA element, results in transcriptional repression of fimA. Furthermore, under these conditions inversion ceases to be dependent on the integration host factor (IHF) or the leucine-responsive regulatory protein (LRP), cofactors hitherto considered to be essential for inversion. Inversion will even occur (albeit at a very low level) in the absence of both cofactors. The interaction of the fimB gene product with the invertible element was studied in vivo in the presence of single- and multicopy fimB genes. Dimethyl sulphoxide (DMS)-mediated methylation of DNA at the 9 bp inverted repeats, which flank the invertible element, was found to vary in the presence and absence of functional fimB. The DMS reactivity profile at the left-hand inverted repeat was similar with single or multicopy fimB. The corresponding profile at the right-hand inverted repeat varied with fimB copy number. As this repeat lies between the fimA promoter and open reading frame, FimB binding here is likely to modulate fimA transcription and vice versa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.681434.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The site-specific recombination system regulating expression of the Type 1 fimbrial subunit gene of Escherichia coli is sensitive to changes in DNA supercoiling (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 14 (1994), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have studied the effect of altering the in vivo level of DNA supercoiling on the phase-variable expression of the Escherichia coli fimA gene. Transcription from the fimA promoter was unaffected by changes in DNA supercoiling whether caused by the introduction of a topA::7n10 mutation or by inhibition of DNA gyrase with the antibiotic novobiocin. However, inversion of the fimA promoter fragment was altered in response to perturbation of DNA supercoiling. Specifically, inactivation of topA reduced the rate of promoter fragment inversion in both the ON-to-OFF and the OFF-to-ON directions. This effect correlated with the loss of functional topA and not with the global level of DNA supercoiling. Inhibition of DNA gyrase introduced a bias in favour of the OFF-to-ON inversion; the ON-to-OFF inversion was affected only slightly. Changes in expression of fimB, the gene coding for the recombinase that catalyses fimA promoter fragment inversion in the strains used In this study, did not correlate with effects on fimA phase variation: we found that transcription of fimB was inhibited by loss of functional topA and was enhanced by inhibition of DNA gyrase in a manner that correlated well with the global level of in vivo DNA supercoiling. A model is presented to account for the effects of lost topoisomerase function on fimA gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1994.tb01332.x
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  • 4
    Electronic Resource
    Electronic Resource
    Region 4 of σ as a target for transcription regulation (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 48 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Bacterial σ factors play a key role in promoter recognition, making direct contact with conserved promoter elements. Most σ factors belong to the σ70 family, named for the primary σ factor in Escherichia coli. Members of the σ70 family typically share four conserved regions and, here, we focus on region 4, which is directly involved in promoter recognition and serves as a target for a variety of regulators of transcription initiation. We review recent advances in the understanding of the mechanism of action of regulators that target region 4 of σ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03467.x
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  • 5
    Electronic Resource
    Electronic Resource
    RshA, an anti-sigma factor that regulates the activity of the mycobacterial stress response sigma factor SigH (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 50 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: SigH, an alternative sigma factor of Mycobacterium tuberculosis,  is  a  central regulator  of  the  response to oxidative and heat stress. Exposure to these stresses results in increased expression of sigH itself, and of genes encoding additional regulators and effectors of the bacterial response to these stresses. In this work we show that RshA, a protein encoded by a gene in the sigH operon, is an anti-sigma factor of SigH. We demonstrate that RshA binds to SigH in vitro and in vivo. This protein–protein interaction, as  well  as the  ability  of RshA to inhibit SigH-dependent transcription, is redox-dependent, with RshA functioning as a negative regulator of SigH activity only under reducing conditions. The interaction of SigH and RshA is also disrupted in vitro by elevated temperature. RshA, a protein of 101 amino acids, contains five conserved cysteine residues of which two appear to be essential for RshA to inhibit SigH activity, suggesting that these cysteines may be important for the redox state dependence of RshA function. Our results indicate that RshA is a sensor that responds to oxidative stress, and also to heat stress, resulting in activation of SigH and expression of the SigH-dependent genes that allow M. tuberculosis to adapt to these stresses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03739.x
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  • 6
    Electronic Resource
    Electronic Resource
    Activation of prokaryotic transcription through arbitrary protein–protein contacts (1997)
    [s.l.] : Nature Publishing Group
    Nature 386 (1997), S. 627-630 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We replaced the carboxy-terminal domain (CTD) of the a-subunit of RNA polymerase (RNAP) (Fig. 1), which is the natural target for many transcriptional activators1"3, with a heterologous protein domain that does not ordinarily mediate transcriptional activation. To do this, we took advantage of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/386627a0
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