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  • 1
    Electronic Resource
    Electronic Resource
    Dissection of a surface-exposed portion of the cAMP–CRP complex that mediates transcription activation and repression (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 32 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The Escherichia coli cAMP receptor protein (CRP) is essential for the activation and repression of transcription initiation at promoters in the CytR regulon. CRP performs these activities by making direct protein–protein interactions to the α-subunits of RNA polymerase and to the CytR regulator. Strikingly, it has been shown that amino acids of CRP that are critical for communication with the two partner proteins are located in close proximity on the surface of CRP. Here, we have dissected this surface in order to pinpoint the ‘repression region’ of CRP and to assess whether it overlaps with the characterized ‘activating region’. Our results established that residues 12, 13, 17, 105, 108 and 110 are essential for the interaction with CytR and confirmed that ‘activating region’ 2 of CRP is made up of residues 19, 21 and 101. In the crystallographic structure of the CRP–DNA complex, the two sets of determinants are located immediately adjacent to each other forming a consecutive surface-exposed patch. The ‘repression region’ is chemically complementary to the characterized region on CytR that is essential for protein–protein communication to CRP. Moreover, the results provide insight into the mechanism by which CytR might prevent CRP-mediated transcription.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01362.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Tandem DNA-bound cAMP-CRP complexes are required for transcriptional repression of the deoP2 promoter by the CytR repressor in Escherichia coli (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 4 (1990), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have studied the deoP2 promoter in Escherichia coli to define features important for its interaction with the CytR repressor. As is characteristic for CytR-regulated promoters, deoP2 encodes tandem binding sites for the activating complex cAMP-CRP. One of these sites, CRP-1, overlaps the - 35 region, and is sufficient for activation; the second site, CRP-2, centred around-93, is indispensable for repression. Here we demonstrate, by means of in vivo titration, that CytR interaction with deoP2 depends not only on CRP-2, but also on CRP-1 and the length and possibly the sequence separating these two sites. Also, point mutations in either CRP site reduce or abolish CytR titration; however, no co-operativity is observed in the interaction of CytR with the two CRP binding sites. Furthermore, the reduction in CytR titration parallels the reduction in binding of cAMP-CRP to the mutated CRP sites in vitro. These observations are not easily explained by current models for the action of prokaryotic repressors; instead we favour a model in which the interaction of CytR with deoP2 depends on the presence of tandem DNA-bound cAMP–CRP complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1990.tb02071.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Design of camp–CRP-activated promoters in Escherichia coli (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have studied the doeP2 promoter of Escherichia coli to define features that are required for optimal activation by the complex of adenosine 3′, 5′ monophosphate (cAMP) and the cAMP receptor protein (CRP). Systematic mutagenesis of deoP2 shows that the distance between the CRP site and the -10 hexamer is the crucial factor in determining whether the promoter is activated by camp–CRP. Based on these observations, we propose that camp–CRP-activated promoters can be created by correctly aligning a CRP target and a - 10 hexamer. This idea has been successfully tested by converting both a CRP-in-dependent promoter and a sequence resembling the consensus -10 hexamer to strongly camp–CRP-activated promoters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1991.tb02126.x
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  • 4
    Electronic Resource
    Electronic Resource
    A novel function of the cAMP-CRP complex in Escherichia coli: cAMP-CRP functions as an adaptor for the CytR repressor in the deo operon (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Unlike classical bacterial repressors, the CytR repressor of Escherichia coli cannot independently regulate gene expression. Here we show that CytR binding to the deoP2 promoter relies on interaction with the master gene regulatory protein, CRP, and, furthermore, that cAMP-CRP and CytR bind co-operatively to deoP2. Using mutant promoters we show that tandem, properly spaced DNA-bound cAMP-CRP complexes are required for this co-operative binding. These data suggest that CytR forms a bridge between tandem cAMP-CRP complexes, and that cAMP-CRP ftjnctions as an adaptor for CytR. The implications of this new version of negative control in E. coli on bacterial gene expression and on combinatorial gene regulation in higher organisms are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1991.tb00772.x
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  • 5
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    Directional intracellular trafficking in bacteria [Commentary] (2011)
    National Academy of Sciences
    Details
    Publication Date: 2011-05-04
    Description: In their natural environments, bacteria often colonize biotic and abiotic surfaces, and the intimate association with biotic surfaces can be a prerequisite for pathogenesis. Once on a surface, cells may remain sessile and simply grow and divide. Alternatively, cells may display active cell movements and translocate across the surface by one of three different mechanisms: swarming, twitching, or gliding (1, 2). Swarming depends on rotating flagella that are randomly distributed on the cell surface and form a bundle that pushes a cell forward (2, 3). Twitching depends on type IV pili, which extend from the cell surface, attach to the...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 6
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    Regulation of cell polarity in bacteria (2014)
    Rockefeller University Press
    Details
    Publication Date: 2014-07-08
    Description: Bacteria are polarized cells with many asymmetrically localized proteins that are regulated temporally and spatially. This spatiotemporal dynamics is critical for several fundamental cellular processes including growth, division, cell cycle regulation, chromosome segregation, differentiation, and motility. Therefore, understanding how proteins find their correct location at the right time is crucial for elucidating bacterial cell function. Despite the diversity of proteins displaying spatiotemporal dynamics, general principles for the dynamic regulation of protein localization to the cell poles and the midcell are emerging. These principles include diffusion-capture, self-assembling polymer-forming landmark proteins, nonpolymer forming landmark proteins, matrix-dependent self-organizing ParA/MinD ATPases, and small Ras-like GTPases.
    Electronic ISSN: 1540-8140
    Topics: Biology
    Published by Rockefeller University Press
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  • 7
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    Evolution and Diversity of the Ras Superfamily of Small GTPases in Prokaryotes (2015)
    Oxford University Press
    Details
    Publication Date: 2015-01-09
    Description: The Ras superfamily of small GTPases are single domain nucleotide-dependent molecular switches that act as highly tuned regulators of complex signal transduction pathways. Originally identified in eukaryotes for their roles in fundamental cellular processes including proliferation, motility, polarity, nuclear transport, and vesicle transport, recent studies have revealed that single domain GTPases also control complex functions such as cell polarity, motility, predation, development and antibiotic resistance in bacteria. Here, we used a computational genomics approach to understand the abundance, diversity, and evolution of small GTPases in prokaryotes. We collected 520 small GTPase sequences present in 17% of 1,611 prokaryotic genomes analyzed that cover diverse lineages. We identified two discrete families of small GTPases in prokaryotes that show evidence of three distinct catalytic mechanisms. The MglA family includes MglA homologs, which are typically associated with the MglB GTPase activating protein, whereas members of the Rup (Ras superfamily GTPase of unknown function in prokaryotes) family are not predicted to interact with MglB homologs. System classification and genome context analyses support the involvement of small GTPases in diverse prokaryotic signal transduction pathways including two component systems, laying the foundation for future experimental characterization of these proteins. Phylogenetic analysis of prokaryotic and eukaryotic GTPases supports that the last universal common ancestor contained ancestral MglA and Rup family members. We propose that the MglA family was lost from the ancestral eukaryote and that the Ras superfamily members in extant eukaryotes are the result of vertical and horizontal gene transfer events of ancestral Rup GTPases.
    Electronic ISSN: 1759-6653
    Topics: Biology
    Published by Oxford University Press
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  • 8
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    The small G-protein MglA connects to the MreB actin cytoskeleton at bacterial focal adhesions (2015)
    Rockefeller University Press
    Details
    Publication Date: 2015-07-21
    Description: In Myxococcus xanthus the gliding motility machinery is assembled at the leading cell pole to form focal adhesions, translocated rearward to propel the cell, and disassembled at the lagging pole. We show that MglA, a Ras-like small G-protein, is an integral part of this machinery. In this function, MglA stimulates the assembly of the motility complex by directly connecting it to the MreB actin cytoskeleton. Because the nucleotide state of MglA is regulated spatially and MglA only binds MreB in the guanosine triphosphate–bound form, the motility complexes are assembled at the leading pole and dispersed at the lagging pole where the guanosine triphosphatase activating protein MglB disrupts the MglA–MreB interaction. Thus, MglA acts as a nucleotide-dependent molecular switch to regulate the motility machinery spatially. The function of MreB in motility is independent of its function in peptidoglycan synthesis, representing a coopted function. Our findings highlight a new function for the MreB cytoskeleton and suggest that G-protein–cytoskeleton interactions are a universally conserved feature.
    Electronic ISSN: 1540-8140
    Topics: Biology
    Published by Rockefeller University Press
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