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1
المؤلفون: Bernardo, Lisandro M D, Johansson, Linda U M, Solera, Dafne, Skärfstad, Eleonore, Shingler, Victoria
المصدر: Molecular Microbiology. 60(3):749-764
مصطلحات موضوعية: DNA-Directed RNA Polymerases/genetics/*metabolism, Escherichia coli/genetics/*metabolism, Escherichia coli Proteins/genetics/*metabolism, Gene Expression Regulation, Bacterial, Guanosine Tetraphosphate/*metabolism, Mutation, Promoter Regions (Genetics), RNA Polymerase Sigma 54/genetics/*metabolism, Sigma Factor/genetics/metabolism, Transcription, Genetic
الوصف: The RNA polymerase-binding protein DksA is a cofactor required for guanosine tetraphosphate (ppGpp)-responsive control of transcription from sigma70 promoters. Here we present evidence: (i) that both DksA and ppGpp are required for in vivo sigma54 transcription even though they do not have any major direct effects on sigma54 transcription in reconstituted in vitro transcription and sigma-factor competition assays, (ii) that previously defined mutations rendering the housekeeping sigma70 less effective at competing with sigma54 for limiting amounts of core RNA polymerase similarly suppress the requirement for DksA and ppGpp in vivo and (iii) that the extent to which ppGpp and DksA affect transcription from sigma54 promoters in vivo reflects the innate affinity of the promoters for sigma54-RNA polymerase holoenzyme in vitro. Based on these findings, we propose a passive model for ppGpp/DksA regulation of sigma54-dependent transcription that depends on the potent negative effects of these regulatory molecules on transcription from powerful stringently regulated sigma70 promoters.
وصف الملف: electronic
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2
المؤلفون: David Hernandez, Patrick Linder, Antoine Huyghe, James E. Cassat, Adrien Nicolas Fischer, Ludwig Stenz, Jacques Schrenzel, Manuela Tangomo, Patrice Francois
المصدر: FEMS Microbiology Letters, Vol. 287, No 2 (2008) pp. 149-55
مصطلحات موضوعية: Staphylococcus aureus, Micrococcaceae, Population, Sigma Factor, medicine.disease_cause, Staphylococcal infections, Microbiology, Bacterial Adhesion, 03 medical and health sciences, chemistry.chemical_compound, Biofilms/drug effects, Oleic Acid/pharmacology, Bacterial Proteins, Genetics, medicine, Humans, education, Molecular Biology, Sigma Factor/genetics/metabolism, 030304 developmental biology, Staphylococcus carnosus, ddc:616, 0303 health sciences, education.field_of_study, Microbial Viability, biology, 030306 microbiology, Bacterial Adhesion/drug effects, Microbial Viability/drug effects, Biofilm, Staphylococcal Infections, biology.organism_classification, medicine.disease, Staphylococcal Infections/microbiology, Oleic acid, chemistry, Biofilms, Bacterial Proteins/genetics/metabolism, Staphylococcus aureus/drug effects/physiology, Bacteria, Oleic Acid
الوصف: Staphylococcus aureus is responsible for a broad variety of chronic infections. Most S. aureus clinical isolates show the capacity to adhere to abiotic surfaces and to develop biofilms. Because S. aureus growing in a biofilm is highly refractory to treatment, inhibition of biofilm formation represents a major therapeutic objective. We evaluated the effects of oleic acid on primary adhesion and biofilm production in eight genotypically different S. aureus strains as well as in the biofilm-negative Staphylococcus carnosus strain TM300. Oleic acid inhibited primary adhesion but increased biofilm production in every S. aureus strain tested. Staphylococcus aureus strain UAMS-1 was then selected as a model organism for studying the mechanisms triggered by oleic acid on the formation of a biofilm in vitro. Oleic acid inhibited the primary adhesion of UAMS-1 dose dependently with an IC(50) around 0.016%. The adherent bacterial population decreased proportionally with increasing concentrations of oleic acid whereas an opposite effect was observed on the planktonic population. Overall, the total bacterial counts remained stable. Macroscopic detachments and clumps were visible from the adherent bacterial population. In the presence of oleic acid, the expression of sigB, a gene potentially involved in bacterial survival through an effect on fatty acid composition, was not induced. Our results suggest a natural protective effect of oleic acid against primary adhesion.
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3
المؤلفون: Jacques Schrenzel, Myriam Girard, Dominik A. Bloes, Bettina Schulthess, Markus Bischoff, Brigitte Berger-Bächi, Patrice Francois
المصدر: Journal of Bacteriology, Vol. 193, No 18 (2011) pp. 4954-62
J Bacteriol.مصطلحات موضوعية: Staphylococcus aureus, Operon, medicine.medical_treatment, Mutant, Virulence, Sigma Factor, Lipase/secretion, Staphylococcus aureus/enzymology/genetics, Microbiology, 03 medical and health sciences, Bacterial Proteins, Sigma factor, medicine, Micrococcal Nuclease, Micrococcal Nuclease/secretion, Molecular Biology, Sigma Factor/genetics/metabolism, 030304 developmental biology, Molecular Biology of Pathogens, ddc:616, 0303 health sciences, Nuclease, Protease, biology, 030306 microbiology, Gene Expression Profiling, fungi, Genetic Complementation Test, Peptide Hydrolases/secretion, Lipase, Gene Expression Regulation, Bacterial, Molecular biology, Regulon, Bacterial Proteins/genetics/metabolism, biology.protein, Gene Deletion, Peptide Hydrolases, Micrococcal nuclease
الوصف: The alternative sigma factor σ B of Staphylococcus aureus is involved in the coordination of the general stress response, expression of virulence determinants, and modulation of antibiotic resistance levels. It controls a large regulon, either directly by recognizing conserved σ B promoter sequences or indirectly via σ B -dependent elements. The σ B -controlled yabJ-spoVG operon encodes two such putative downstream elements. We report here transcriptome analysis in S. aureus Newman, showing that inactivation of the yabJ-spoVG operon had primarily a repressing effect on a small subregulon encoding mainly virulence factors, including a nuclease ( nuc ), a protease ( splE ) and a lipase ( lip ). As a consequence, extracellular nuclease, protease, and lipase activities were reduced in a Δ yabJ - spoVG mutant. trans -complementation by SpoVG was sufficient to restore their reduced phenotypic expression and lowered transcription due to the yabJ-spoVG deletion. It did not restore, however, the changes triggered by σ B inactivation, indicating that both regulons only partially overlap, despite the σ B dependency of the yabJ-spoVG expression. Thus, σ B is likely to control additional, SpoVG-independent factors affecting the expression of numerous hydrolytic enzymes. SpoVG, on the other hand, seems to fine-tune the σ B -dependent regulation of a subset of virulence factors by antagonizing the σ B effect.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3e99b390b0a7115447bfbcc84b4f6c7a
https://doi.org/10.1128/jb.05362-11 -
4
المؤلفون: Dafne Solera, Linda Johansson, Eleonore Skärfstad, Victoria Shingler, Lisandro M. D. Bernardo
المصدر: Molecular Microbiology. 60:749-764
مصطلحات موضوعية: Gene Expression Regulation, Bacterial, Stringent response, Escherichia coli Proteins/genetics/*metabolism, Guanosine, DNA-Directed RNA Polymerases/genetics/*metabolism, Transcription, Genetic, Biology, Microbiology, RNA Polymerase Sigma 54/genetics/*metabolism, Escherichia coli/genetics/*metabolism, chemistry.chemical_compound, Transcription (biology), RNA polymerase, heterocyclic compounds, Guanosine Tetraphosphate/*metabolism, Molecular Biology, Sigma Factor/genetics/metabolism, RNA, Promoter, Guanosine Tetraphosphate, chemistry, Biochemistry, Mutation, bacteria, Promoter Regions (Genetics), Alarmone
الوصف: The RNA polymerase-binding protein DksA is a cofactor required for guanosine tetraphosphate (ppGpp)-responsive control of transcription from sigma70 promoters. Here we present evidence: (i) that both DksA and ppGpp are required for in vivo sigma54 transcription even though they do not have any major direct effects on sigma54 transcription in reconstituted in vitro transcription and sigma-factor competition assays, (ii) that previously defined mutations rendering the housekeeping sigma70 less effective at competing with sigma54 for limiting amounts of core RNA polymerase similarly suppress the requirement for DksA and ppGpp in vivo and (iii) that the extent to which ppGpp and DksA affect transcription from sigma54 promoters in vivo reflects the innate affinity of the promoters for sigma54-RNA polymerase holoenzyme in vitro. Based on these findings, we propose a passive model for ppGpp/DksA regulation of sigma54-dependent transcription that depends on the potent negative effects of these regulatory molecules on transcription from powerful stringently regulated sigma70 promoters.
وصف الملف: application/pdf
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5
المؤلفون: Thilo Köhler, Christian van Delden, Malcolm G. P. Page
المصدر: Antimicrobial Agents and Chemotherapy, Vol. 57, No 5 (2013) pp. 2095-102
مصطلحات موضوعية: Siderophore, Operon, Mutant, Siderophores, Aztreonam, medicine.disease_cause, Ceftazidime, Ion Transport/drug effects, chemistry.chemical_compound, Drug Resistance, Multiple, Bacterial/drug effects/genetics, Sigma factor, Drug Resistance, Multiple, Bacterial, Pharmacology (medical), ddc:616, Siderophores/pharmacology, Iron Deficiencies, Pseudomonas aeruginosa/drug effects/genetics/metabolism, Anti-Bacterial Agents, Infectious Diseases, Carrier Proteins/genetics/metabolism, Pseudomonas aeruginosa, Bacterial Proteins/genetics/metabolism, Efflux, Ceftazidime/pharmacology, Iron/deficiency/metabolism, Monobactams, Iron, Sigma Factor, Microbial Sensitivity Tests, Biology, Aztreonam/pharmacology, beta-Lactamases, Microbiology, Anti-Bacterial Agents/pharmacology, Thiazoles/metabolism/pharmacology, Bacterial Proteins, Phenols, Mechanisms of Resistance, medicine, Phenols/metabolism, Gene, Gene Expression Regulation, Bacterial/drug effects, Sigma Factor/genetics/metabolism, Pharmacology, Ion Transport, Gene Expression Regulation, Bacterial, Beta-Lactamases/genetics/metabolism, Thiazoles, chemistry, Monobactams/pharmacology, Mutation, bacteria, Carrier Proteins
الوصف: BAL30072 is a monosulfactam conjugated with an iron-chelating dihydroxypyridone moiety. It is active against Gram-negative bacteria, including multidrug-resistant Pseudomonas aeruginosa . We selected mutants with decreased susceptibilities to BAL30072 in P. aeruginosa PAO1 under a variety of conditions. Under iron-deficient conditions, mutants with overexpression of AmpC β-lactamase predominated. These mutants were cross-resistant to aztreonam and ceftazidime. Similar mutants were obtained after selection at >16× the MIC in iron-sufficient conditions. At 4× to 8× the MIC, mutants with elevated MIC for BAL30072 but unchanged MICs for aztreonam or ciprofloxacin were selected. The expression of ampC and the major efflux pump genes were also unchanged. These BAL30072-specific mutants were characterized by transcriptome analysis, which revealed upregulation of the Fe-dicitrate operon, FecIRA. Whole-genome sequencing showed that this resulted from a single nucleotide change in the Fur-box of the fecI promoter. Overexpression of either the FecI ECF sigma factor or the FecA receptor increased BAL30072 MICs 8- to 16-fold. A fecI mutant and a fecA mutant of PAO1 were hypersusceptible to BAL30072 (MICs < 0.06 μg/ml). The most downregulated gene belonged to the pyochelin synthesis operon, although mutants in pyochelin receptor or synthesis genes had unchanged MICs. The piuC gene, coding for a Fe(II)-dependent dioxygenase located next to the piuA iron receptor gene, was also downregulated. The MICs of BAL30072 for piuC and piuA transposon mutants were increased 8- and 16-fold, respectively. We conclude that the upregulation of the Fe-dicitrate system impacts the expression of other TonB-dependent iron transporters and that PiuA and PiuC contribute to the susceptibility of P. aeruginosa PAO1 to BAL30072.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::45ff9507e110797c7fa4e7720e9e2f02
https://pubmed.ncbi.nlm.nih.gov/23422914 -
6
المؤلفون: Brigitte Berger-Bächi, Akihito Wada, Markus Bischoff, Jasmina Putnik, Martin Roos, Philipp Glanzmann, Pierre Vaudaux, Philipp Giachino
المساهمون: University of Zurich, Berger-Bächi, B
المصدر: FEMS Microbiology Letters, Vol. 194, No 1 (2001) pp. 77-82
مصطلحات موضوعية: Operon, Peptidoglycan/analysis, medicine.disease_cause, Cell Wall, Transduction, Genetic, Drug Resistance, Multiple/genetics, ddc:616, Genetics, Mutation, Strain (chemistry), Pigments, Biological/metabolism, 10179 Institute of Medical Microbiology, Teicoplanin, 2404 Microbiology, Chromosome Mapping, Drug Resistance, Microbial, Drug Resistance, Multiple, Anti-Bacterial Agents, Staphylococcus aureus, Bacterial Proteins/genetics/metabolism, Operon/genetics, medicine.drug, DNA, Bacterial, Drug Resistance, Microbial/genetics, Anti-Bacterial Agents/ pharmacology, Blotting, Western, 610 Medicine & health, Sigma Factor, Microbial Sensitivity Tests, Peptidoglycan, Biology, Microbiology, Cell wall, 1311 Genetics, Bacterial Proteins, Staphylococcus aureus/ drug effects/ genetics, 1312 Molecular Biology, medicine, Animals, Humans, Molecular Biology, Transcription factor, Sigma Factor/genetics/metabolism, Pigments, Biological, biochemical phenomena, metabolism, and nutrition, Cell Wall/chemistry, bacterial infections and mycoses, Rats, carbohydrates (lipids), Transformation (genetics), Teicoplanin/ pharmacology, 570 Life sciences, biology, bacteria, Transformation, Bacterial
الوصف: Teicoplanin resistance was transformed from a teicoplanin-resistant Staphylococcus aureus into the susceptible strain BB255 to give strain BB938. The cell wall composition, amidation of the iD-glutamate, and peptide crosslinking were identical in BB938 as in BB255 except for a 60% increased length of the glycan chain. Transductional crosses revealed that at least two distinct loci contributed in a cumulative fashion to teicoplanin resistance. One of these loci correlated with a mutation inactivating the anti-sigma factor RsbW. This mutation must have occurred during transformation and selection for teicoplanin resistance in BB938. Genetic manipulations involving the sigB operon showed that transcription factor SigB contributed to decreased teicoplanin susceptibility.
وصف الملف: 194-1-77.pdf - application/pdf
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7
المؤلفون: Rachel Comte, And Marc Bally, Christian van Delden
المصدر: Journal of Bacteriology, Vol. 183, No 18 (2001) pp. 5376-5384
مصطلحات موضوعية: Transcription, Genetic, Stringent response, Physiology and Metabolism, Sigma Factor, Trans-Activators/genetics/metabolism, Biology, medicine.disease_cause, Microbiology, Ligases, 4-Butyrolactone, Bacterial Proteins, Sigma factor, Ligases/genetics/metabolism, Serine, medicine, Homeodomain Proteins/genetics/metabolism, Molecular Biology, Sigma Factor/genetics/metabolism, Homeodomain Proteins, Regulation of gene expression, ddc:616, Pseudomonas aeruginosa, Gene Expression Regulation, Bacterial, biochemical phenomena, metabolism, and nutrition, Culture Media, Pseudomonas aeruginosa/ drug effects/genetics/ growth & development/metabolism, DNA-Binding Proteins, Quorum sensing, Serine/analogs & derivatives/ pharmacology, DNA-Binding Proteins/genetics/metabolism, Mutation, Trans-Activators, Bacterial Proteins/genetics/metabolism, bacteria, Autoinducer, Signal transduction, rpoS, Culture Media/chemistry, Signal Transduction
الوصف: During nutrient starvation, Escherichia coli elicits a stringent response involving the ribosome-associated protein RelA. Activation of RelA results in a global change in the cellular metabolism including enhanced expression of the stationary-phase sigma factor RpoS. In the human pathogen Pseudomonas aeruginosa , a complex quorum-sensing circuitry, linked to RpoS expression, is required for cell density-dependent production of many secreted virulence factors, including LasB elastase. Quorum sensing relies on the activation of specific transcriptional regulators (LasR and RhlR) by their corresponding autoinducers (3-oxo-C 12 -homoserine lactone [HSL] and C 4 -HSL), which function as intercellular signals. We found that overexpression of relA activated the expression of rpoS in P. aeruginosa and led to premature, cell density-independent LasB elastase production. We therefore investigated the effects of the stringent response on quorum sensing. Both lasR and rhlR gene expression and autoinducer synthesis were prematurely activated during the stringent response induced by overexpression of relA . Premature expression of lasR and rhlR was also observed when relA was overexpressed in a PAO1 rpoS mutant. The stringent response induced by the amino acid analogue serine hydroxamate (SHX) also led to premature production of the 3-oxo-C 12 -HSL autoinducer. This response to SHX was absent in a PAO1 relA mutant. These findings suggest that the stringent response can activate the two quorum-sensing systems of P. aeruginosa independently of cell density.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c0ad5c9662d72a5ac042abcb2cf2515b
https://archive-ouverte.unige.ch/unige:7625 -
8مورد إلكتروني
مستخلص: The RNA polymerase-binding protein DksA is a cofactor required for guanosine tetraphosphate (ppGpp)-responsive control of transcription from sigma70 promoters. Here we present evidence: (i) that both DksA and ppGpp are required for in vivo sigma54 transcription even though they do not have any major direct effects on sigma54 transcription in reconstituted in vitro transcription and sigma-factor competition assays, (ii) that previously defined mutations rendering the housekeeping sigma70 less effective at competing with sigma54 for limiting amounts of core RNA polymerase similarly suppress the requirement for DksA and ppGpp in vivo and (iii) that the extent to which ppGpp and DksA affect transcription from sigma54 promoters in vivo reflects the innate affinity of the promoters for sigma54-RNA polymerase holoenzyme in vitro. Based on these findings, we propose a passive model for ppGpp/DksA regulation of sigma54-dependent transcription that depends on the potent negative effects of these regulatory molecules on transcription from powerful stringently regulated sigma70 promoters.
مصطلحات الفهرس: DNA-Directed RNA Polymerases/genetics/*metabolism, Escherichia coli/genetics/*metabolism, Escherichia coli Proteins/genetics/*metabolism, Gene Expression Regulation; Bacterial, Guanosine Tetraphosphate/*metabolism, Mutation, Promoter Regions (Genetics), RNA Polymerase Sigma 54/genetics/*metabolism, Sigma Factor/genetics/metabolism, Transcription; Genetic, Article in journal, info:eu-repo/semantics/article, text
URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-16715
Molecular Microbiology, 0950-382X, 2006, 60:3, s. 749-764 -
9مورد إلكتروني
مستخلص: The RNA polymerase-binding protein DksA is a cofactor required for guanosine tetraphosphate (ppGpp)-responsive control of transcription from sigma70 promoters. Here we present evidence: (i) that both DksA and ppGpp are required for in vivo sigma54 transcription even though they do not have any major direct effects on sigma54 transcription in reconstituted in vitro transcription and sigma-factor competition assays, (ii) that previously defined mutations rendering the housekeeping sigma70 less effective at competing with sigma54 for limiting amounts of core RNA polymerase similarly suppress the requirement for DksA and ppGpp in vivo and (iii) that the extent to which ppGpp and DksA affect transcription from sigma54 promoters in vivo reflects the innate affinity of the promoters for sigma54-RNA polymerase holoenzyme in vitro. Based on these findings, we propose a passive model for ppGpp/DksA regulation of sigma54-dependent transcription that depends on the potent negative effects of these regulatory molecules on transcription from powerful stringently regulated sigma70 promoters.
مصطلحات الفهرس: DNA-Directed RNA Polymerases/genetics/*metabolism, Escherichia coli/genetics/*metabolism, Escherichia coli Proteins/genetics/*metabolism, Gene Expression Regulation; Bacterial, Guanosine Tetraphosphate/*metabolism, Mutation, Promoter Regions (Genetics), RNA Polymerase Sigma 54/genetics/*metabolism, Sigma Factor/genetics/metabolism, Transcription; Genetic, Article in journal, info:eu-repo/semantics/article, text
URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-16715
Molecular Microbiology, 0950-382X, 2006, 60:3, s. 749-764 -
10مورد إلكتروني
مستخلص: The RNA polymerase-binding protein DksA is a cofactor required for guanosine tetraphosphate (ppGpp)-responsive control of transcription from sigma70 promoters. Here we present evidence: (i) that both DksA and ppGpp are required for in vivo sigma54 transcription even though they do not have any major direct effects on sigma54 transcription in reconstituted in vitro transcription and sigma-factor competition assays, (ii) that previously defined mutations rendering the housekeeping sigma70 less effective at competing with sigma54 for limiting amounts of core RNA polymerase similarly suppress the requirement for DksA and ppGpp in vivo and (iii) that the extent to which ppGpp and DksA affect transcription from sigma54 promoters in vivo reflects the innate affinity of the promoters for sigma54-RNA polymerase holoenzyme in vitro. Based on these findings, we propose a passive model for ppGpp/DksA regulation of sigma54-dependent transcription that depends on the potent negative effects of these regulatory molecules on transcription from powerful stringently regulated sigma70 promoters.
مصطلحات الفهرس: DNA-Directed RNA Polymerases/genetics/*metabolism, Escherichia coli/genetics/*metabolism, Escherichia coli Proteins/genetics/*metabolism, Gene Expression Regulation; Bacterial, Guanosine Tetraphosphate/*metabolism, Mutation, Promoter Regions (Genetics), RNA Polymerase Sigma 54/genetics/*metabolism, Sigma Factor/genetics/metabolism, Transcription; Genetic, Article in journal, info:eu-repo/semantics/article, text
URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-16715
Molecular Microbiology, 0950-382X, 2006, 60:3, s. 749-764
