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BMC Microbiology Jun 2021The global rise in the incidence of non-tuberculosis mycobacterial infections is of increasing concern due their high levels of intrinsic antibiotic resistance. Although...
BACKGROUND
The global rise in the incidence of non-tuberculosis mycobacterial infections is of increasing concern due their high levels of intrinsic antibiotic resistance. Although integrated viral genomes, called prophage, are linked to increased antibiotic resistance in some bacterial species, we know little of their role in mycobacterial drug resistance.
RESULTS
We present here for the first time, evidence of increased antibiotic resistance and expression of intrinsic antibiotic resistance genes in a strain of Mycobacterium chelonae carrying prophage. Strains carrying the prophage McProf demonstrated increased resistance to amikacin. Resistance in these strains was further enhanced by exposure to sub-inhibitory concentrations of the antibiotic, acivicin, or by the presence of a second prophage, BPs. Increased expression of the virulence gene, whiB7, was observed in strains carrying both prophages, BPs and McProf, relative to strains carrying a single prophage or no prophages.
CONCLUSIONS
This study provides evidence that prophage alter expression of important mycobacterial intrinsic antibiotic resistance genes and additionally offers insight into the role prophage may play in mycobacterial adaptation to stress.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Drug Resistance, Bacterial; Mycobacterium chelonae; Prophages; Virulence Factors
PubMed: 34107872
DOI: 10.1186/s12866-021-02224-z -
Cellular Microbiology Mar 2019Helicobacter saguini is a novel enterohepatic Helicobacter species isolated from captive cotton top tamarins with chronic colitis and colon cancer. Monoassociated...
BACKGROUND
Helicobacter saguini is a novel enterohepatic Helicobacter species isolated from captive cotton top tamarins with chronic colitis and colon cancer. Monoassociated H. saguini infection in gnotobiotic IL-10 mice causes typhlocolitis and dysplasia; however, the virulent mechanisms of this species are unknown. Gamma-glutamyltranspeptidase (GGT) is an enzymatic virulence factor expressed by pathogenic Helicobacter and Campylobacter species that inhibits host cellular proliferation and promotes inflammatory-mediated gastrointestinal pathology. The aim of this study was to determine if H. saguini expresses an enzymatically active GGT homologue with virulence properties.
EXPERIMENTAL PROCEDURES
Two putative GGT paralogs (HSGGT1 and HSGGT2) identified in the H. saguini genome were bioinformatically analysed to predict enzymatic functionality and virulence potential. An isogenic knockout mutant strain and purified recombinant protein of HSGGT1 were created to study enzymatic activity and virulence properties by in vitro biochemical and cell culture experiments.
RESULTS
Bioinformatic analysis predicted that HSGGT1 has enzymatic functionality and is most similar to the virulent homologue expressed by Helicobacter bilis, whereas HSGGT2 contains putatively inactivating mutations. An isogenic knockout mutant strain and recombinant HSGGT1 protein were successfully created and demonstrated that H. saguini has GGT enzymatic activity. Recombinant HSGGT1 protein and sonicate from wild-type but not mutant H. saguini inhibited gastrointestinal epithelial and lymphocyte cell proliferation without evidence of cell death. The antiproliferative effect by H. saguini sonicate or recombinant HSGGT1 protein could be significantly prevented with glutamine supplementation or the GGT-selective inhibitor acivicin. Recombinant HSGGT1 protein also induced proinflammatory gene expression in colon epithelial cells.
CONCLUSIONS
This study shows that H. saguini may express GGT as a potential virulence factor and supports further in vitro and in vitro studies into how GGT expression by enterohepatic Helicobacter species influences the pathogenesis of gastrointestinal inflammatory diseases.
Topics: Animals; Cell Survival; Chronic Disease; Colitis; Computational Biology; Epithelial Cells; Gene Expression; Gene Knockout Techniques; Helicobacter; Interleukin-10; Mice, Knockout; Recombinant Proteins; Saguinus; Virulence Factors; gamma-Glutamyltransferase
PubMed: 30365223
DOI: 10.1111/cmi.12968 -
Experimental Eye Research Jan 2018In this study, we have investigated whether the lens was capable of exporting the antioxidant glutathione. Pairs of rat lenses were cultured in isosmotic artificial...
In this study, we have investigated whether the lens was capable of exporting the antioxidant glutathione. Pairs of rat lenses were cultured in isosmotic artificial aqueous humour for one, two, three, or six hours in low oxygen conditions (90% N, 5% CO, 5% O), and reduced glutathione (GSH) and oxidised glutathione (GSSG) levels measured in the media and lenses. We show that the rat lens is capable of releasing ∼5 nmol GSH for each time point suggesting that GSH release is regulated since it does not appreciably increase over time. We also demonstrated that the predominant form of glutathione released was the reduced form. We next cultured lenses in the absence or presence of acivicin, a γ-glutamyl transpeptidase (GGT) inhibitor, and found that GSH levels were significantly increased (p < 0.001) in the presence of this inhibitor, which indicated that GSH released by the lens undergoes degradation into its constituent amino acids. GSH release was significantly decreased (p < 0.001) in the presence of 100 μM MK571, a multidrug resistance-associated protein (Mrp) inhibitor, suggesting that Mrp transporters mediate GSH efflux from the lens. Culturing lenses in low (10 μM) or high (70 μM) concentrations of HO for one hour significantly increased total glutathione levels (p < 0.05) relative to controls, due to the increased release of GSSG. Our results show that in response to oxidative stress, the rat lens is able to release GSH or GSSG, thereby serving to maintain lens redox state or potentially influence the redox state of nearby tissues.
Topics: Animals; Aqueous Humor; Glutathione; Hydrogen Peroxide; L-Lactate Dehydrogenase; Lens, Crystalline; Models, Animal; Oxidative Stress; Rats; Rats, Wistar
PubMed: 29032155
DOI: 10.1016/j.exer.2017.10.010 -
Current Drug Discovery Technologies 2023Green strategy involves the design, synthesis, processing, and use of chemical substances by eliminating the generation of chemical hazards. This approach focuses on...
BACKGROUND
Green strategy involves the design, synthesis, processing, and use of chemical substances by eliminating the generation of chemical hazards. This approach focuses on atom economy, use of safer solvents or chemicals, consumption of energy, and decomposition of the chemical substances to non-toxic materials which are eco-friendly.
OBJECTIVE
So, the microwave irradiated heating method is considered a green and sustainable technique for the development of novel heterocyclic scaffold-like isoxazole derivatives via chalcones. Isoxazole derivatives play a vital role due to their diverse pharmacological activities such as antibiotic (Sulfamethoxazole, Cloxacillin, Flucloxacillin, Cycloserine), anti-fungal (Drazoxolon), Antirheumatic (Leflunomide), antidepressant (Isocarboxazid), antineoplastic (Acivicin), anticonvulsant (Zonisamide), antipsychotic (Risperidone) and anti-inflammatory drugs (Valdecoxib), etc. Methods: The isoxazole derivatives were synthesized with the help of microwave irradiation that follows green chemistry protocol.
RESULTS
The titled compounds were subjected to antiepileptic evaluation to determine their therapeutic potential.
CONCLUSION
The use of microwave radiation enhances the rate of the reaction which leads to high selectivity with improved product yields in comparison with the traditional heating methods. The tested compounds exhibited promising antiepileptic activity as compared to the standard drug (Phenytoin).
Topics: Anticonvulsants; Isoxazoles; Chalcones; Anti-Bacterial Agents; Solvents
PubMed: 36790007
DOI: 10.2174/1570163820666230215125043 -
The Biochemical Journal Oct 2014Amino acid transporters are crucial for parasite survival since the cellular metabolism of parasitic protozoa depends on the up-take of exogenous amino acids. Amino acid...
Amino acid transporters are crucial for parasite survival since the cellular metabolism of parasitic protozoa depends on the up-take of exogenous amino acids. Amino acid transporters are also of high pharmacological relevance because they may mediate uptake of toxic amino acid analogues. In the present study we show that the eflornithine transporter AAT6 from Trypanosoma brucei (TbAAT6) mediates growth on neutral amino acids when expressed in Saccharomyces cerevisiae mutants. The transport was electrogenic and further analysed in Xenopus laevis oocytes. Neutral amino acids, proline analogues, eflornithine and acivicin induced inward currents. For proline, glycine and tryptophan the apparent affinities and maximal transport rates increased with more negative membrane potentials. Proline-induced currents were dependent on pH, but not on sodium. Although proline represents the primary energy source of T. brucei in the tsetse fly, down-regulation of TbAAT6-expression by RNAi showed that in culture TbAAT6 is not essential for growth of procyclic form trypanosomes in the presence of glucose or proline as energy source. TbAAT6-RNAi lines of both bloodstream and procyclic form trypanosomes showed reduced susceptibility to eflornithine, whereas the sensitivity to acivicin remained unchanged, indicating that acivicin enters the cell by more than one transporter.
Topics: Amino Acid Transport Systems, Neutral; Amino Acids; Animals; Biological Transport, Active; Down-Regulation; Drug Resistance; Eflornithine; Enzyme Inhibitors; Hydrogen-Ion Concentration; Isoxazoles; Membrane Potentials; Protozoan Proteins; Trypanocidal Agents; Trypanosoma brucei brucei; Xenopus
PubMed: 24988048
DOI: 10.1042/BJ20140719 -
Molecules (Basel, Switzerland) Apr 2020is the aetiologic agent of Chagas disease, which affects people in the Americas and worldwide. The parasite has a complex life cycle that alternates among mammalian...
is the aetiologic agent of Chagas disease, which affects people in the Americas and worldwide. The parasite has a complex life cycle that alternates among mammalian hosts and insect vectors. During its life cycle, passes through different environments and faces nutrient shortages. It has been established that amino acids, such as proline, histidine, alanine, and glutamate, are crucial to survival. Recently, we described that can biosynthesize glutamine from glutamate and/or obtain it from the extracellular environment, and the role of glutamine in energetic metabolism and metacyclogenesis was demonstrated. In this study, we analysed the effect of glutamine analogues on the parasite life cycle. Here, we show that glutamine analogues impair cell proliferation, the developmental cycle during the infection of mammalian host cells and metacyclogenesis. Taken together, these results show that glutamine is an important metabolite for survival and suggest that glutamine analogues can be used as scaffolds for the development of new trypanocidal drugs. These data also reinforce the supposition that glutamine metabolism is an unexplored possible therapeutic target.
Topics: Animals; Azaserine; CHO Cells; Cell Cycle; Cell Proliferation; Cricetulus; Energy Metabolism; Glutamic Acid; Glutamine; Isoxazoles; Life Cycle Stages; Molecular Structure; Trypanocidal Agents; Trypanosoma cruzi
PubMed: 32252252
DOI: 10.3390/molecules25071628 -
Biosensors & Bioelectronics Jul 2016The first near-infrared fluorescent probe with excellent water-solubility for γ-glutamyl transpeptidase (GGT) has been developed by combining glutathione (GSH) as a...
The first near-infrared fluorescent probe with excellent water-solubility for γ-glutamyl transpeptidase (GGT) has been developed by combining glutathione (GSH) as a recognition unit with a near-infrared hemicyanine fluorophore through an acrylyl linker. The probe exhibits a highly selective and sensitive fluorescent off-on response to GGT with a detection limit of 0.50U/L, and the response mechanism is based on the enzyme-catalyzed cleavage of the γ-glutamyl bond of GSH, followed by the spontaneous intramolecular cyclization and the release of the fluorophore. Notably, the probe has been used to image GGT in zebrafish and evaluate the inhibition ability of three common inhibitors of GGT both in vitro and in vivo, revealing that their inhibition efficiencies are acivicin >6-diazo-5-oxo-L-norleucine >L-serine-borate complex, and their corresponding IC50 values are 0.11±0.01mM, 0.34±0.04mM and 2.06±0.24mM, respectively. The proposed probe is simple, and may have great potential for screening GGT inhibitors.
Topics: Animals; Enzyme Assays; Enzyme Inhibitors; Fluorescent Dyes; Humans; Infrared Rays; Optical Imaging; Solubility; Spectrometry, Fluorescence; Water; Zebrafish; Zebrafish Proteins; gamma-Glutamyltransferase
PubMed: 26995285
DOI: 10.1016/j.bios.2016.03.021 -
ChemMedChem Apr 2017The natural product acivicin inhibits the glutaminase activity of cytidine triphosphate (CTP) synthetase and is a potent lead compound for drug discovery in the area of...
The natural product acivicin inhibits the glutaminase activity of cytidine triphosphate (CTP) synthetase and is a potent lead compound for drug discovery in the area of neglected tropical diseases, specifically trypanosomaisis. A 2.1-Å-resolution crystal structure of the acivicin adduct with the glutaminase domain from Trypanosoma brucei CTP synthetase has been deposited in the RCSB Protein Data Bank (PDB) and provides a template for structure-based approaches to design new inhibitors. However, our assessment of that data identified deficiencies in the model. We now report an improved and corrected inhibitor structure with changes to the chirality at one position, the orientation and covalent structure of the isoxazoline moiety, and the location of a chloride ion in an oxyanion binding site that is exploited during catalysis. The model is now in agreement with established chemical principles and allows an accurate description of molecular recognition of the ligand and the mode of binding in a potentially valuable drug target.
Topics: Bacillus subtilis; Carbon-Nitrogen Ligases; Catalytic Domain; Glutaminase; Helicobacter pylori; Hydrogen Bonding; Isoxazoles; Ligands; Trypanocidal Agents; Trypanosoma brucei brucei; gamma-Glutamyltransferase
PubMed: 28333400
DOI: 10.1002/cmdc.201700118 -
Chemical Science Dec 2014Acivicin is a natural product with diverse biological activities. Several decades ago its clinical application in cancer treatment was explored but failed due to...
Target discovery of acivicin in cancer cells elucidates its mechanism of growth inhibition†Electronic supplementary information (ESI) available: Synthesis, cloning, protein expression, purification and biochemical assays. See DOI: 10.1039/c4sc02339k.
Acivicin is a natural product with diverse biological activities. Several decades ago its clinical application in cancer treatment was explored but failed due to unacceptable toxicity. The causes behind the desired and undesired biological effects have never been elucidated and only limited information about acivicin-specific targets is available. In order to elucidate the target spectrum of acivicin in more detail we prepared functionalized derivatives and applied them for activity based proteomic profiling (ABPP) in intact cancer cells. Target deconvolution by quantitative mass spectrometry (MS) revealed a preference for specific aldehyde dehydrogenases. Further in depth target validation confirmed that acivicin inhibits ALDH4A1 activity by binding to the catalytic site. In accordance with this, downregulation of ALDH4A1 by siRNA resulted in a severe inhibition of cell growth and might thus provide an explanation for the cytotoxic effects of acivicin.
PubMed: 25580214
DOI: 10.1039/c4sc02339k -
The Protein Journal Feb 2017Gamma glutamyl transpeptidase, (GGT) is a ubiquitous protein which plays a central role in glutathione metabolism and has myriad clinical implications. It has been shown...
Gamma glutamyl transpeptidase, (GGT) is a ubiquitous protein which plays a central role in glutathione metabolism and has myriad clinical implications. It has been shown to be a virulence factor for pathogenic bacteria, inhibition of which results in reduced colonization potential. However, existing inhibitors are effective but toxic and therefore search is on for novel inhibitors, which makes it imperative to understand the interactions of various inhibitors with the protein in substantial detail. High resolution structures of protein bound to different inhibitors can serve this purpose. Gamma glutamyl transpeptidase from Bacillus licheniformis is one of the model systems that have been used to understand the structure-function correlation of the protein. The structures of the native protein (PDB code 4OTT), of its complex with glutamate (PDB code 4OTU) and that of its precursor mimic (PDB code 4Y23) are available, although at moderate/low resolution. In the present study, we are reporting the preliminary analysis of, high resolution X-ray diffraction data collected for the co-crystals of B. licheniformis, Gamma glutamyl transpeptidase, with its inhibitor, Acivicin. Crystals belong to the orthorhombic space group P222 and diffract X-ray to 1.45 Å resolution. This is the highest resolution data reported for all GGT structures available till now. The use of SUMO fused expression system enhanced yield of the target protein in the soluble fraction, facilitating recovery of protein with high purity. The preliminary analysis of this data set shows clear density for the inhibitor, acivicin, in the protein active site.
Topics: Bacillus licheniformis; Gene Expression; Isoxazoles; Recombinant Fusion Proteins; SUMO-1 Protein; X-Ray Diffraction; gamma-Glutamyltransferase
PubMed: 28120227
DOI: 10.1007/s10930-017-9693-2