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  • 1
    Language: English
    In: The Journal of biological chemistry, 27 May 2016, Vol.291(22), pp.11477-90
    Description: Allicin (diallyl thiosulfinate) from garlic is a highly potent natural antimicrobial substance. It inhibits growth of a variety of microorganisms, among them antibiotic-resistant strains. However, the precise mode of action of allicin is unknown. Here, we show that growth inhibition of Escherichia coli during allicin exposure coincides with a depletion of the glutathione pool and S-allylmercapto modification of proteins, resulting in overall decreased total sulfhydryl levels. This is accompanied by the induction of the oxidative and heat stress response. We identified and quantified the allicin-induced modification S-allylmercaptocysteine for a set of cytoplasmic proteins by using a combination of label-free mass spectrometry and differential isotope-coded affinity tag labeling of reduced and oxidized thiol residues. Activity of isocitrate lyase AceA, an S-allylmercapto-modified candidate protein, is largely inhibited by allicin treatment in vivo Allicin-induced protein modifications trigger protein aggregation, which largely stabilizes RpoH and thereby induces the heat stress response. At sublethal concentrations, the heat stress response is crucial to overcome allicin stress. Our results indicate that the mode of action of allicin is a combination of a decrease of glutathione levels, unfolding stress, and inactivation of crucial metabolic enzymes through S-allylmercapto modification of cysteines.
    Keywords: Escherichia Coli (E. Coli) ; S-Allylmercapto Modification ; Allicin ; Antibiotic Action ; Bacteria ; Disulfide ; Garlic (Allium Sativum) ; Redox Proteomics ; Thiol ; Escherichia Coli -- Drug Effects ; Escherichia Coli Proteins -- Metabolism ; Plant Extracts -- Pharmacology ; Sulfhydryl Compounds -- Metabolism ; Sulfinic Acids -- Pharmacology
    ISSN: 00219258
    E-ISSN: 1083-351X
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  • 2
    Language: English
    In: Applied Microbiology and Biotechnology, 2014, Vol.98(14), pp.6205-6213
    Description: Plasma is ionized gas, which is found in various forms in nature and can also be generated artificially. A variety of cold atmospheric-pressure plasmas are currently being investigated for their clinical utility, and first studies reporting on the treatment of patients showed that plasma treatment may support the wound healing process. One of the benefits of plasma treatment is the effective inactivation of bacteria including tenacious pathogens such as Pseudomonas aeruginosa or multiresistant Staphylococcus aureus (MRSA). Neither the molecular mechanisms promoting wound healing nor those underlying bacterial inactivation are fully understood yet. The review has a focus on plasma jets, a particular type of cold atmospheric-pressure plasma sources featuring an indirect treatment whereby the treated substrates do not come into contact with the plasma directly but are exposed to the plasma-emitted reactive species and photons. Such plasma jets are being employed as tools in basic research regarding the effects of plasmas on biological samples. This review provides a brief overview on the recent clinical investigations into the benefits of cold atmospheric-pressure plasmas. It then describes our current understanding of the mechanisms leading to bacterial inactivation and inactivation of biomacromolecules gained by employing plasma jets.
    Keywords: Cold atmospheric-pressure plasma ; Plasma jet ; Dielectric barrier discharge ; Clinical application ; Bacterial inactivation ; Biomacromolecules
    ISSN: 0175-7598
    E-ISSN: 1432-0614
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  • 3
    Language: English
    In: Journal of Physics D: Applied Physics, 2014, Vol.47(8), p.085402 (9pp)
    Description: Plasma sterilization is a promising alternative to commonly used sterilization techniques, because the conventional methods suffer from certain limitations, e.g. incompatibility with heat-sensitive materials, or use of toxic agents. However, plasma-based sterilization mechanisms are not fully understood yet. A low-pressure very high frequency capacitively coupled plasma is used to investigate the impact of a hydrogen discharge on the protein glyceraldehyde 3-phosphate dehydrogenase (GapDH). GapDH is an enzyme of glycolysis. As a part of the central metabolism, it occurs in nearly all organisms from bacteria to humans. The plasma is investigated with absolutely calibrated optical emission spectroscopy in order to identify and to quantify plasma components that can contribute to enzyme inactivation. The contribution of UV photons and heat to GapDH inactivation is investigated separately, and neither seems to be a major factor. In order to investigate the mechanisms of GapDH inactivation by the hydrogen discharge, samples are investigated for etching, induction of amino acid backbone breaks, and chemical modifications. While neither etching nor strand breaks are observed, chemical modifications occur at different amino acid residues of GapDH. Deamidations of asparagines as well as methionine and cysteine oxidations are detected after VHF-CCP treatment. In particular, oxidation of the cysteine in the active centre is known to lead to GapDH inactivation.
    Keywords: Inactivation ; Bacteria ; Amino Acids ; Photons ; Enzymes ; Plasma (Physics) ; Etching ; Sterilization ; Applied Physics (General) (So) ; Physics (General) (Ah) ; Optical Emission Spectroscopy ; Macromolecules ; Mass Spectrometry ; Plasma Sterilization;
    ISSN: 0022-3727
    E-ISSN: 1361-6463
    Source: IOPscience (IOP Publishing)
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  • 4
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 08 April 2014, Vol.111(14), pp.E1409-18
    Description: Short antimicrobial peptides rich in arginine (R) and tryptophan (W) interact with membranes. To learn how this interaction leads to bacterial death, we characterized the effects of the minimal pharmacophore RWRWRW-NH2. A ruthenium-substituted derivative of this peptide localized to the membrane in vivo, and the peptide also integrated readily into mixed phospholipid bilayers that resemble Gram-positive membranes. Proteome and Western blot analyses showed that integration of the peptide caused delocalization of peripheral membrane proteins essential for respiration and cell-wall biosynthesis, limiting cellular energy and undermining cell-wall integrity. This delocalization phenomenon also was observed with the cyclic peptide gramicidin S, indicating the generality of the mechanism. Exogenous glutamate increases tolerance to the peptide, indicating that osmotic destabilization also contributes to antibacterial efficacy. Bacillus subtilis responds to peptide stress by releasing osmoprotective amino acids, in part via mechanosensitive channels. This response is triggered by membrane-targeting bacteriolytic peptides of different structural classes as well as by hypoosmotic conditions.
    Keywords: Hypoosmotic Stress Response ; Mechanism of Action ; Metallocenes ; Respiratory Chain ; Antimicrobial Cationic Peptides -- Metabolism ; Membrane Proteins -- Metabolism
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 5
    Language: English
    In: Journal of Physics D: Applied Physics, 2015, Vol.48(44), p.444001 (12pp)
    Description: A microscale atmospheric-pressure plasma jet is a remote plasma jet, where plasma-generated reactive particles and photons are involved in substrate treatment. Here, we summarize our efforts to develop and characterize a particle- or photon-selective set of otherwise identical jets. In that way, the reactive species or photons can be used separately or in combination to study their isolated or combined effects to test whether the effects are additive or synergistic. The final version of the set of three jets—particle-jet, photon-jet and combined jet—is introduced. This final set realizes the highest reproducibility of the photon and particle fluxes, avoids turbulent gas flow, and the fluxes of the selected plasma-emitted components are almost identical in the case of all jets, while the other component is effectively blocked, which was verified by optical emission spectroscopy and mass spectrometry. Schlieren-imaging and a fluid dynamics simulation show the stability of the gas flow. The performance of these selective jets is demonstrated with the example of the treatment of E. coli bacteria with the different components emitted by a He-only, a He/N 2 and a He/O 2 plasma. Additionally, measurements of the vacuum UV photon spectra down to the wavelength of 50 nm can be made with the photon-jet and the relative comparison of spectral intensities among different gas mixtures is reported here. The results will show that the vacuum UV photons can lead to the inactivation of the E.coli bacteria.
    Keywords: Bacteria ; Photons ; Fluid Dynamics ; Plasma (Physics) ; Spectra ; Particles (of Physics) ; Gas Flow ; Fluxes ; Applied Physics (General) (So) ; Physics (General) (Ah);
    ISSN: 0022-3727
    E-ISSN: 1361-6463
    Source: IOPscience (IOP Publishing)
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  • 6
    In: European Journal of Inorganic Chemistry, 13 July 2018, Vol.2018(26), pp.3104-3112
    Description: Organometallic N‐heterocyclic carbene (NHC) complexes with intercalating bis‐naphthalimide ligands were prepared and evaluated biologically. Cytotoxic effects against tumor cells or bacteria were strongly ligand dependent with minor influence of the metal (Ag, Ru, Rh, Au) centers. Complex with a rhodium(I) NHC moiety was studied in more detail for its DNA interacting properties in comparison to the metal free ligand. These studies showed a good DNA binding pattern with some preference for the telomeric quadruplex structure Telo. Complex was also shown to trigger additional coordinative binding to the DNA and therefore represents an useful tool compound with a mixed intercalative/coordinative DNA binding mode. Organometallic N‐heterocyclic carbene (NHC) complexes with intercalating bis‐naphthalimide ligands were studied as cytotoxic and antimicrobial agents. The DNA interaction of a selected example was study in detailed and confirmed a mixed intercalative‐coordinative mode of DNA interaction.
    Keywords: Antitumor Agents ; Carbenes ; Copper ; Gold ; Silver ; Rhodium ; Ruthenium
    ISSN: 1434-1948
    E-ISSN: 1099-0682
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  • 7
    Language: English
    In: Current protocols in microbiology, August 2012, Vol.Chapter 1, pp.Unit1F.2
    Description: The global analysis of changes in the protein composition of bacterial cells in response to treatment with antibiotic agents grants insights into the physiological response of cells to inhibition of vital cellular functions. This unit gives an overview of how global proteomic studies can impact antibacterial drug discovery by identifying or validating compound mechanism of action and by increasing the confidence in the value of genes with unknown function as potential new targets. It describes the design and function of a reference compendium of proteomic responses to inhibition of vital cellular functions through antibacterial agents or genetic down-regulation of potential target genes. An overview of the workflow for two-dimensional gel electrophoresis-based experiments is also presented.
    Keywords: Drug Discovery ; Anti-Bacterial Agents -- Pharmacology ; Bacteria -- Chemistry ; Electrophoresis, Gel, Two-Dimensional -- Methods ; Proteomics -- Methods
    ISSN: 19348525
    E-ISSN: 1934-8533
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 8
    In: Journal of Bacteriology, Jan, 2002, Vol.184(1-2), p.459(9)
    Description: Results reveal that in Bacillus subtilis the sigma(sup)B -dependent stress response is induced in the presence of rifampin. Data suggest that the sigma(sup)B response overcomes the rifampin-induced growth arrest by the activity of the RsbP energy-signaling phosphatase of the sigma(sup)B signal transduction network.
    Keywords: Rifampin -- Physiological Aspects ; Microbial Drug Resistance -- Physiological Aspects ; Cellular Signal Transduction -- Physiological Aspects ; Bacterial Growth -- Physiological Aspects
    ISSN: 0021-9193
    Source: Cengage Learning, Inc.
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  • 9
    In: The Journal of Bacteriology, 2002, Vol. 184(2), p.459
    Description: Low concentrations of the RNA polymerase inhibitor rifampin added to an exponentially growing culture of Bacillus subtilis led to an instant inhibition of growth. Survival experiments revealed that during the growth arrest the cells became tolerant to the antibiotic and the culture was able to resume growth some time after rifampin treatment. L-[ super(35)S]methionine pulse- labeled protein extracts were separated by two-dimensional polyacrylamide gel electrophoresis to investigate the change in the protein synthesis pattern in response to rifampin. The capital sigma super(B)-dependent general stress proteins were found to be induced after treatment with the antibiotic. Part of the oxidative stress signature was induced as indicated by the catalase KatA and MrgA. The target protein of rifampin, the s subunit (RpoB) of the DNA-dependent RNA polymerase, and the flagellin protein Hag belonging to the capital sigma super(D) regulon were also induced. The rifampin-triggered growth arrest was extended in a sigB mutant in comparison to the wild-type strain, and the higher the concentration, the more pronounced this effect was. Activity of the RsbP energy-signaling phosphatase in the capital sigma super(B) signal transduction network was also important for this protection against rifampin, but the RsbU environmental signaling phosphatase was not required. The sigB mutant strain was less capable of growing on rifampin-containing agar plates. When plated from a culture that had already reached stationary phase without previous exposure to the antibiotic during growth, the survival rate of the wild type exceeded that of the sigB mutant by a factor of 100. We conclude that the general stress response of B. subtilis is induced by rifampin depending on RsbP activity and that loss of SigB function causes increased sensitivity to the antibiotic.
    Keywords: Bacillus Subtilis ; Bacillus Subtilis ; Stress ; Rifampin ; Antibiotic Resistance ; Stress ; Rifampin ; Antibiotic Resistance ; Sigb Gene ; Sigb Gene ; Antibiotic Resistance ; Microbial Resistance ; Sigb Gene;
    ISSN: 0021-9193
    ISSN: 00219193
    E-ISSN: 10985530
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  • 10
    Language: English
    In: mBio, 01 November 2018, Vol.9(6), p.e02100-18
    Description: The alphaproteobacterium Agrobacterium tumefaciens is able to infect various eudicots causing crown gall tumor formation. Based on its unique ability of interkingdom gene transfer, Agrobacterium serves as a crucial biotechnological tool for genetic manipulation of plant cells. The presence of hundreds of putative sRNAs in this organism suggests a considerable impact of riboregulation on A. tumefaciens physiology. Here, we characterized the biological function of the sRNA PmaR that controls various processes crucial for growth, motility, and virulence. Among the genes directly targeted by PmaR is ampC coding for a beta-lactamase that confers ampicillin resistance, suggesting that the sRNA is crucial for fitness in the competitive microbial composition of the rhizosphere.Small regulatory RNAs play an important role in the adaptation to changing conditions. Here, we describe a differentially expressed small regulatory RNA (sRNA) that affects various cellular processes in the plant pathogen Agrobacterium tumefaciens. Using a combination of bioinformatic predictions and comparative proteomics, we identified nine targets, most of which are positively regulated by the sRNA. According to these targets, we named the sRNA PmaR for peptidoglycan biosynthesis, motility, and ampicillin resistance regulator. Agrobacterium spp. are long known to be naturally resistant to high ampicillin concentrations, and we can now explain this phenotype by the positive PmaR-mediated regulation of the beta-lactamase gene ampC. Structure probing revealed a spoon-like structure of the sRNA, with a single-stranded loop that is engaged in target interaction in vivo and in vitro. Several riboregulators have been implicated in antibiotic resistance mechanisms, such as uptake and efflux transporters, but PmaR represents the first example of an sRNA that directly controls the expression of an antibiotic resistance gene.
    Keywords: Antibiotic Resistance ; Gene Regulation ; Plant-Microbe Interaction ; Posttranscriptional Control ; Regulatory RNA ; Biology
    ISSN: 21612129
    E-ISSN: 2150-7511
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