33 results on '"Pountain, Andrew"'
Search Results
2. Author response: Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress
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Podkowik, Magdalena, primary, Perault, Andrew, additional, Putzel, Gregory, additional, Pountain, Andrew, additional, Kim, Jisun, additional, DuMont, Ashley, additional, Zwack, Erin, additional, Ulrich, Robert, additional, Kargounis, Theodora, additional, Zhou, Chunyi, additional, Haag, Andreas, additional, Shenderovich, Julia, additional, Wasserman, Gregory, additional, Kwon, Junbeom, additional, Chen, John, additional, Richardson, Anthony Robert, additional, Weiser, Jeff, additional, Nowosad, Carla, additional, Lun, Desmond, additional, Parker, Dane, additional, Pironti, Alejandro, additional, Zhao, Xilin, additional, Drlica, Karl, additional, Yanai, Itai, additional, Torres, Victor J, additional, and Shopsin, Bo, additional
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- 2024
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3. Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress
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Podkowik, Magdalena, primary, Perault, Andrew I., additional, Putzel, Gregory, additional, Pountain, Andrew, additional, Kim, Jisun, additional, Dumont, Ashley, additional, Zwack, Erin, additional, Ulrich, Robert J., additional, Karagounis, Theodora K., additional, Zhou, Chunyi, additional, Haag, Andreas F., additional, Shenderovich, Julia, additional, Wasserman, Gregory A., additional, Kwon, Junbeom, additional, Chen, John, additional, Richardson, Anthony R., additional, Weiser, Jeffrey N., additional, Nowosad, Carla R., additional, Lun, Desmond S., additional, Parker, Dane, additional, Pironti, Alejandro, additional, Zhao, Xilin, additional, Drlica, Karl, additional, Yanai, Itai, additional, Torres, Victor J., additional, and Shopsin, Bo, additional
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- 2024
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4. Genetic and metabolic mechanisms of amphotericin B resistance in Leishmania parasites
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Pountain, Andrew William
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616.9 ,QR Microbiology - Abstract
Pathogenic protozoa of the genus Leishmania pose a significant burden on global health. Control relies on a limited range of chemotherapeutic options, with amphotericin B of increasing importance. Understanding how resistance may emerge to this drug is therefore of some concern. As amphotericin B acts through its affinity for leishmanial sterols, altered sterol composition has been described. However, little is known about the genetic basis of these changes. In this thesis, selection and characterisation of four novel amphotericin B-resistant L. mexicana lines are described. Changes to parasite drug sensitivity and fitness were profiled, as well as alterations in metabolism. This revealed heterogeneity between lines, suggesting that many changes arise stochastically during selection of resistance. In one line, no fitness costs to infectivity and replication in primary macrophages were found. Hypersensitivity to the drug pentamidine, however, was a consistent phenotype. All parasites demonstrated altered sterol composition. Genetic and transcriptomic profiling revealed associated changes in sterol biosynthesis genes, with mutation in sterol C5-desaturase observed in one line and loss of sterol C24-methyltransferase expression apparent in the other three. Broader analysis revealed extensive and apparently stochastic transcriptome remodelling, associated with chromosomal copy number changes. Deletion of the miltefosine transporter was found in one line, associated with miltefosine cross-resistance. Through reintroduction of candidate genes into resistant lines, a role for these changes was demonstrated in both amphotericin B resistance and pentamidine hypersensitivity. Reintroduction of sterol biosynthesis genes, but not the miltefosine transporter, was associated with at least partial restoration of wild-type sterol composition. Finally, changes to the sterol C24-methyltransferase locus were investigated, revealing that structural variations are the basis of expression changes, possibly mediated by repetitive sequences at this locus. These data demonstrate multiple routes to drug resistance, and suggest that at least some of these routes allow retention of parasite infectivity. Evidence of structural instability at the locus of sterol C24-methyltransferase, associated with altered sterol composition and drug resistance, is of particular concern.
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- 2018
5. Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress.
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Podkowik, Magdalena, Perault, Andrew I., Putzel, Gregory, Pountain, Andrew, Jisun Kim, DuMont, Ashley L., Zwack, Erin E., Ulrich, Robert J., Karagounis, Theodora K., Chunyi Zhou, Haag, Andreas F., Shenderovich, Julia, Wasserman, Gregory A., Junbeom Kwon, John Chen, Richardson, Anthony R., Weiser, Jeffrey N., Nowosad, Carla R., Lun, Desmond S., and Parker, Dane
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- 2024
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6. Candida auris —macrophage cellular interactions and transcriptional response
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Miramón, Pedro, primary, Pountain, Andrew W., additional, and Lorenz, Michael C., additional
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- 2023
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7. Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress
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Podkowik, Magdalena, primary, Perault, Andrew I., additional, Putzel, Gregory, additional, Pountain, Andrew, additional, Kim, Jisun, additional, Dumont, Ashley, additional, Zwack, Erin, additional, Ulrich, Robert J., additional, Karagounis, Theodora K., additional, Zhou, Chunyi, additional, Haag, Andreas F., additional, Shenderovich, Julia, additional, Wasserman, Gregory A., additional, Kwon, Junbeom, additional, Chen, John, additional, Richardson, Anthony R., additional, Weiser, Jeffrey N., additional, Nowosad, Carla R., additional, Lun, Desmond S., additional, Parker, Dane, additional, Pironti, Alejandro, additional, Zhao, Xilin, additional, Drlica, Karl, additional, Yanai, Itai, additional, Torres, Victor J., additional, and Shopsin, Bo, additional
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- 2023
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8. Quorum-sensingagrsystem ofStaphylococcus aureusprimes gene expression for protection from lethal oxidative stress
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Podkowik, Magdalena, primary, Perault, Andrew I., additional, Putzel, Gregory, additional, Pountain, Andrew, additional, Kim, Jisun, additional, Dumont, Ashley, additional, Zwack, Erin, additional, Ulrich, Robert J., additional, Karagounis, Theodora K., additional, Zhou, Chunyi, additional, Haag, Andreas F., additional, Shenderovich, Julia, additional, Wasserman, Gregory A., additional, Kwon, Junbeom, additional, Chen, John, additional, Richardson, Anthony R., additional, Weiser, Jeffrey N., additional, Nowosad, Carla R., additional, Lun, Desmond S., additional, Parker, Dane, additional, Pironti, Alejandro, additional, Zhao, Xilin, additional, Drlica, Karl, additional, Yanai, Itai, additional, Torres, Victor J., additional, and Shopsin, Bo, additional
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- 2023
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9. Transcription-replication interactions reveal principles of bacterial genome regulation
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Yanai, Itai, primary, Pountain, Andrew, additional, Jiang, Peien, additional, Yao, Tianyou, additional, Homaee, Ehsan, additional, Guan, Yichao, additional, Podkowik, Magdalena, additional, Shopsin, Bo, additional, Torres, Victor, additional, and Golding, Ido, additional
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- 2023
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10. Transcription-replication interactions reveal principles of bacterial genome regulation
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Pountain, Andrew W., primary, Jiang, Peien, additional, Yao, Tianyou, additional, Homaee, Ehsan, additional, Guan, Yichao, additional, Podkowik, Magdalena, additional, Shopsin, Bo, additional, Torres, Victor J., additional, Golding, Ido, additional, and Yanai, Itai, additional
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- 2022
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11. The tempo and mode of gene regulatory programs during bacterial infection
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Avital, Gal, primary, Kuperwaser, Felicia, additional, Pountain, Andrew W., additional, Lacey, Keenan A., additional, Zwack, Erin E., additional, Podkowik, Magdalena, additional, Shopsin, Bo, additional, Torres, Victor J., additional, and Yanai, Itai, additional
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- 2022
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12. Amphotericin B resistance in Leishmania mexicana: Alterations to sterol metabolism and oxidative stress response
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Alpizar-Sosa, Edubiel A., primary, Ithnin, Nur Raihana Binti, additional, Wei, Wenbin, additional, Pountain, Andrew W., additional, Weidt, Stefan K., additional, Donachie, Anne M., additional, Ritchie, Ryan, additional, Dickie, Emily A., additional, Burchmore, Richard J. S., additional, Denny, Paul W., additional, and Barrett, Michael P., additional
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- 2022
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13. Interactions of Both Pathogenic and Nonpathogenic CUG Clade Candida Species with Macrophages Share a Conserved Transcriptional Landscape
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Pountain, Andrew W., primary, Collette, John R., additional, Farrell, William M., additional, and Lorenz, Michael C., additional
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- 2021
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14. Amphotericin B resistance in Leishmania mexicana: Alterations to sterol metabolism, lipid transport and oxidative stress response
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Alpizar-Sosa, Edubiel A., primary, Binti Ithnin, Nur Raihana, additional, Wei, Wenbin, additional, Pountain, Andrew W., additional, Weidt, Stefan K., additional, Donachie, Anne M., additional, Ritchie, Ryan, additional, Dickie, Emily A., additional, Burchmore, Richard J. S., additional, Denny, Paul W., additional, and Barrett, Michael P., additional
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- 2021
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15. Untargeted metabolomics to understand the basis of phenotypic differences in amphotericin B-resistant
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Pountain, Andrew W. and Barrett, Michael P.
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parasitic diseases - Abstract
Background: Protozoan Leishmania parasites are responsible for a range of clinical infections that represent a substantial challenge for global health. Amphotericin B (AmB) is increasingly used to treat Leishmania infection, so understanding the potential for resistance to this drug is an important priority. Previously we described four independently-derived AmB-resistant L. mexicana lines that exhibited resistance-associated genetic lesions resulting in altered sterol content. However, substantial phenotypic variation between these lines, including differences in virulence attributes, were not fully explained by these changes.\ud Methods: To identify alterations in cellular metabolism potentially related to phenotypic differences between wild-type and AmB-resistant lines, we extracted metabolites and performed untargeted metabolomics by liquid chromatography-mass spectrometry.\ud Results: We observed substantial differences in metabolite abundance between lines, arising in an apparently stochastic manner. Concerted remodeling of central carbon metabolism was not observed; however, in three lines, decreased abundance of several oligohexoses was observed. Given that the oligomannose mannogen is an important virulence factor in Leishmania, this could relate to loss of virulence in these lines. Increased abundance of the reduced forms of the oxidative stress-protective thiols trypanothione and glutathione was also observed in multiple lines.\ud Conclusions: This dataset will provide a useful resource for understanding the molecular basis of drug resistance in Leishmania, and suggests a role for metabolic changes separate from the primary mechanism of drug resistance in determining the phenotypic profile of parasite lines subjected to experimental selection of resistance.
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- 2019
16. Veterinary trypanocidal benzoxaboroles are peptidase-activated prodrugs
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Giordani, Federica, primary, Paape, Daniel, additional, Vincent, Isabel M., additional, Pountain, Andrew W., additional, Fernández-Cortés, Fernando, additional, Rico, Eva, additional, Zhang, Ning, additional, Morrison, Liam J., additional, Freund, Yvonne, additional, Witty, Michael J., additional, Peter, Rosemary, additional, Edwards, Darren Y., additional, Wilkes, Jonathan M., additional, van der Hooft, Justin J. J., additional, Regnault, Clément, additional, Read, Kevin D., additional, Horn, David, additional, Field, Mark C., additional, and Barrett, Michael P., additional
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- 2020
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17. The Paralogous Transcription Factors Stp1 and Stp2 of Candida albicans Have Distinct Functions in Nutrient Acquisition and Host Interaction
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Miramón, Pedro, primary, Pountain, Andrew W., additional, van Hoof, Ambro, additional, and Lorenz, Michael C., additional
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- 2020
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18. Iminosugars counteract the downregulation of the interferon γ receptor by dengue virus
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Miller, Joanna L., primary, Hill, Michelle L., additional, Brun, Juliane, additional, Pountain, Andrew, additional, Sayce, Andrew C., additional, and Zitzmann, Nicole, additional
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- 2019
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19. Genomic instability at the locus of sterol C24-methyltransferase promotes amphotericin B resistance in Leishmania parasites
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Pountain, Andrew W., Weidt, Stefan K., Regnault, Clément, Bates, Paul A., Donachie, Anne M., Dickens, Nicholas J., and Barrett, Michael P.
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Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
Amphotericin B is an increasingly important tool in efforts to reduce the global disease burden posed by Leishmania parasites. With few other chemotherapeutic options available for the treatment of leishmaniasis, the potential for emergent resistance to this drug is a considerable threat. Here we characterised four novel amphotericin B-resistant Leishmania mexicana lines. All lines exhibited altered sterol biosynthesis, and hypersensitivity to pentamidine. Whole genome sequencing demonstrated resistance-associated mutation of the sterol biosynthesis gene sterol C5-desaturase in one line. However, in three out of four lines, RNA-seq revealed loss of expression of sterol C24-methyltransferase (SMT) responsible for drug resistance and altered sterol biosynthesis. Additional loss of the miltefosine transporter was associated with one of those lines. SMT is encoded by two tandem gene copies, which we found to have very different expression levels. In all cases, reduced overall expression was associated with loss of the 3' untranslated region of the dominant gene copy, resulting from structural variations at this locus. Local regions of sequence homology, between the gene copies themselves, and also due to the presence of SIDER1 retrotransposon elements that promote multi-gene amplification, correlate to these structural variations. Moreover, in at least one case loss of SMT expression was not associated with loss of virulence in primary macrophages or in vivo. Whilst such repeat sequence-mediated instability is known in Leishmania genomes, its presence associated with resistance to a major antileishmanial drug, with no evidence of associated fitness costs, is a significant concern.
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- 2019
20. Deletion of transketolase triggers a stringent metabolic response in promastigotes and loss of virulence in amastigotes of Leishmania mexicana
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KOVÁ, Julie, 1¤A, Andrew, DÉRIC BRINGAUD, Fré, KOVÁŘOVÁ, Julie, POUNTAIN, Andrew, WILDRIDGE, David, WEIDT, Stefan, BRINGAUD, Frédéric, BURCHMORE, Richard, ACHCAR, Fiona, BARRETT, Michael, University of Glasgow, Centre de résonance magnétique des systèmes biologiques (CRMSB), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Institut Jacques Monod (IJM (UMR_7592)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux, CNRS, ANR-11-LABX-0024,ParaFrap,Alliance française contre les maladies parasitaires(2011), European Project: 290080,EC:FP7:PEOPLE,FP7-PEOPLE-2011-ITN,PARAMET(2012), Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB), Résonance magnétique des systèmes biologiques (RMSB), and Université Bordeaux Segalen - Bordeaux 2-Centre National de la Recherche Scientifique (CNRS)
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[SDV.MP.PAR]Life Sciences [q-bio]/Microbiology and Parasitology/Parasitology - Abstract
International audience; Transketolase (TKT) is part of the non-oxidative branch of the pentose phosphate pathway (PPP). Here we describe the impact of removing this enzyme from the pathogenic protozoan Leishmania mexicana. Whereas the deletion had no obvious effect on cultured promastigote forms of the parasite, the Δtkt cells were not virulent in mice. Δtkt promastigotes were more susceptible to oxidative stress and various leishmanicidal drugs than wild-type, and metabolomics analysis revealed profound changes to metabolism in these cells. In addition to changes consistent with those directly related to the role of TKT in the PPP, central carbon metabolism was substantially decreased, the cells consumed significantly less glucose, flux through glycolysis diminished, and production of the main end products of metabolism was decreased. Only minor changes in RNA abundance from genes encoding enzymes in central carbon metabolism, however, were detected although fructose-1,6-bisphosphate aldolase activity was decreased twofold in the knockout cell line. We also showed that the dual localisation of TKT between cytosol and glycosomes is determined by the C-terminus of the enzyme and by engineering different variants of the enzyme we could alter its sub-cellular localisation. However, no effect on the overall flux of glucose was noted irrespective of whether the enzyme was found uniquely in either compartment, or in both.
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- 2018
21. Metabolomic profiling of macrophages determines the discrete metabolomic signature and metabolomic interactome triggered by polarising immune stimuli
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Rattigan, Kevin M., Pountain, Andrew W., Regnault, Clement, Achcar, Fiona, Vincent, Isabel M., Goodyear, Carl S., and Barrett, Michael P.
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Metabolic Processes ,Lipopolysaccharides ,Ovalbumin ,Immune Cells ,Immunology ,Citric Acid Cycle ,Immunoglobulins ,lcsh:Medicine ,Pathology and Laboratory Medicine ,Biochemistry ,White Blood Cells ,Interferon-gamma ,Signs and Symptoms ,Animal Cells ,Diagnostic Medicine ,Medicine and Health Sciences ,Metabolites ,Animals ,Metabolomics ,lcsh:Science ,Immune Response ,Cells, Cultured ,Inflammation ,Blood Cells ,Organic Compounds ,Macrophages ,Organic Chemistry ,lcsh:R ,Chemical Compounds ,Biology and Life Sciences ,Cell Biology ,Amino Acid Metabolism ,Mice, Inbred C57BL ,Chemistry ,Metabolism ,Pyrimidines ,Physical Sciences ,Purine Metabolism ,Metabolome ,lcsh:Q ,Metabolic Pathways ,Cellular Types ,Research Article - Abstract
Priming and activating immune stimuli have profound effects on macrophages, however, studies generally evaluate stimuli in isolation rather than in combination. In this study we have investigated the effects of pro-inflammatory and anti-inflammatory stimuli either alone or in combination on macrophage metabolism. These stimuli include host factors such as IFNγ and ovalbumin-immunoglobulin immune complexes, or pathogen factors such as LPS. Untargeted LC-MS based metabolomics provided an in-depth profile of the macrophage metabolome, and revealed specific changes in metabolite abundance upon either individual stimuli or combined stimuli. Here, by factoring in an interaction term in the linear model, we define the metabolome interactome. This approach allowed us to determine whether stimuli interact in a synergistic or antagonistic manner. In conclusion this study demonstrates a robust approach to interrogate immune-metabolism, especially systems that model host-pathogen interactions.
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- 2018
22. Deletion of transketolase triggers a stringent metabolic response in promastigotes and loss of virulence in amastigotes of Leishmania mexicana
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Kovářová, Julie, Pountain, Andrew W., Wildridge, David, Weidt, Stefan, Bringaud, Frédéric, Burchmore, Richard J. S., Achcar, Fiona, Barrett, Michael P., University of Glasgow, Centre de résonance magnétique des systèmes biologiques (CRMSB), and Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)
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Life Cycles ,Enzyme Metabolism ,Leishmania mexicana ,Protozoan Proteins ,Protozoology ,Biochemistry ,Monocytes ,Mice ,Glucose Metabolism ,Drug Metabolism ,Medicine and Health Sciences ,Biology (General) ,Enzyme Chemistry ,Sequence Deletion ,Mice, Inbred BALB C ,Virulence ,Organic Compounds ,Monosaccharides ,Chemistry ,Physical Sciences ,Metabolome ,Carbohydrate Metabolism ,Protozoan Life Cycles ,Transketolase ,Glycolysis ,Research Article ,Cell Physiology ,QH301-705.5 ,Carbohydrates ,Leishmaniasis, Cutaneous ,Microbiology ,Parasitic Diseases ,Metabolomics ,Animals ,Pharmacokinetics ,[SDV.MP.PAR]Life Sciences [q-bio]/Microbiology and Parasitology/Parasitology ,Pharmacology ,Life Cycle Stages ,Promastigotes ,Organic Chemistry ,Chemical Compounds ,Biology and Life Sciences ,Cell Biology ,RC581-607 ,Cell Metabolism ,Oxidative Stress ,Metabolism ,Glucose ,Enzymology ,Immunologic diseases. Allergy ,Developmental Biology - Abstract
Transketolase (TKT) is part of the non-oxidative branch of the pentose phosphate pathway (PPP). Here we describe the impact of removing this enzyme from the pathogenic protozoan Leishmania mexicana. Whereas the deletion had no obvious effect on cultured promastigote forms of the parasite, the Δtkt cells were not virulent in mice. Δtkt promastigotes were more susceptible to oxidative stress and various leishmanicidal drugs than wild-type, and metabolomics analysis revealed profound changes to metabolism in these cells. In addition to changes consistent with those directly related to the role of TKT in the PPP, central carbon metabolism was substantially decreased, the cells consumed significantly less glucose, flux through glycolysis diminished, and production of the main end products of metabolism was decreased. Only minor changes in RNA abundance from genes encoding enzymes in central carbon metabolism, however, were detected although fructose-1,6-bisphosphate aldolase activity was decreased two-fold in the knock-out cell line. We also showed that the dual localisation of TKT between cytosol and glycosomes is determined by the C-terminus of the enzyme and by engineering different variants of the enzyme we could alter its sub-cellular localisation. However, no effect on the overall flux of glucose was noted irrespective of whether the enzyme was found uniquely in either compartment, or in both., Author summary Leishmania parasites endanger over 1 billion people worldwide, infecting 300,000 people and causing 20,000 deaths annually. In this study, we scrutinized metabolism in Leishmania mexicana after deletion of the gene encoding transketolase (TKT), an enzyme involved in sugar metabolism via the pentose phosphate pathway which plays key roles in creating ribose 5-phosphate for nucleotide synthesis and also defence against oxidative stress. The insect stage of the parasite, grown in culture medium, did not suffer from any obvious growth defect after the gene was deleted. However, its metabolism changed dramatically, with metabolomics indicating profound changes to flux through the pentose phosphate pathway: decreased glucose consumption, and generally enhanced efficiency in using metabolic substrates with reduced secretion of partially oxidised end products of metabolism. This ‘stringent’ metabolism is reminiscent of the mammalian stage parasites. The cells were also more sensitive to oxidative stress inducing agents and leishmanicidal drugs. Crucially, mice inoculated with the TKT knock-out parasites did not develop an infection pointing to the enzyme playing a key role in allowing the parasites to remain viable in the host, indicating that TKT may be considered a useful target for development of new drugs against leishmaniasis.
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- 2018
23. Drug resistance and treatment failure in leishmaniasis: A 21st century challenge
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Ponte-Sucre, Alicia, Gamarro, Francisco, Dujardin, Jean-Claude, Barrett, Michael P., López-Vélez, Rogelio, García-Hernández, Raquel, Pountain, Andrew W., and Mwenechanya, Roy
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Reevaluation of treatment guidelines for Old and New World leishmaniasis is urgently needed on a global basis because treatment failure is an increasing problem. Drug resistance is a fundamental determinant of treatment failure, although other factors also contribute to this phenomenon, including the global HIV/AIDS epidemic with its accompanying impact on the immune system. Pentavalent antimonials have been used successfully worldwide for the treatment of leishmaniasis since the first half of the 20th century, but the last 10 to 20 years have witnessed an increase in clinical resistance, e.g., in North Bihar in India. In this review, we discuss the meaning of “resistance” related to leishmaniasis and discuss its molecular epidemiology, particularly for Leishmania donovani that causes visceral leishmaniasis. We also discuss how resistance can affect drug combination therapies. Molecular mechanisms known to contribute to resistance to antimonials, amphotericin B, and miltefosine are also outlined.
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- 2017
24. Sterol 14?-demethylase mutation leads to amphotericin B resistance in Leishmania mexicana
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Mwenechanya, Roy, Kovarova, Julie, Dickens, Nicholas J., Mudaliar, Manikhandan, Herzyk, Pawel, Vicent, Isabel M., Weidt, Stefan K., Burgess, Karl E., Burchmore, Richard J.S., Pountain, Andrew W., Smith, Terry K., Creek, Darren J., Kim, Dong-Hyun, Lepesheva, Galina I., and Barrett, Michael P.
- Abstract
Amphotericin B has emerged as the therapy of choice for use against the leishmaniases. Administration of the drug in its liposomal formulation as a single injection is being promoted in a campaign to bring the leishmaniases under control. Understanding the risks and mechanisms of resistance is therefore of great importance. Here we select amphotericin B-resistant Leishmania mexicana parasites with relative ease. Metabolomic analysis demonstrated that ergosterol, the sterol known to bind the drug, is prevalent in wild-type cells, but diminished in the resistant line, where alternative sterols become prevalent. This indicates that the resistance phenotype is related to loss of drug binding. Comparing sequences of the parasites’ genomes revealed a plethora of single nucleotide polymorphisms that distinguish wild-type and resistant cells, but only one of these was found to be homozygous and associated with a gene encoding an enzyme in the sterol biosynthetic pathway, sterol 14α-demethylase (CYP51). The mutation, N176I, is found outside of the enzyme’s active site, consistent with the fact that the resistant line continues to produce the enzyme’s product. Expression of wild-type sterol 14α-demethylase in the resistant cells caused reversion to drug sensitivity and a restoration of ergosterol synthesis, showing that the mutation is indeed responsible for resistance. The amphotericin B resistant parasites become hypersensitive to pentamidine and also agents that induce oxidative stress. This work reveals the power of combining polyomics approaches, to discover the mechanism underlying drug resistance as well as offering novel insights into the selection of resistance to amphotericin B itself.
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- 2017
25. Sterol 14α-demethylase mutation leads to amphotericin B resistance in Leishmania mexicana
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Mwenechanya, Roy, primary, Kovářová, Julie, additional, Dickens, Nicholas J., additional, Mudaliar, Manikhandan, additional, Herzyk, Pawel, additional, Vincent, Isabel M., additional, Weidt, Stefan K., additional, Burgess, Karl E., additional, Burchmore, Richard J. S., additional, Pountain, Andrew W., additional, Smith, Terry K., additional, Creek, Darren J., additional, Kim, Dong-Hyun, additional, Lepesheva, Galina I., additional, and Barrett, Michael P., additional
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- 2017
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26. Population genomics reveals the origin and asexual evolution of human infective trypanosomes
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Weir, William, primary, Capewell, Paul, additional, Foth, Bernardo, additional, Clucas, Caroline, additional, Pountain, Andrew, additional, Steketee, Pieter, additional, Veitch, Nicola, additional, Koffi, Mathurin, additional, De Meeûs, Thierry, additional, Kaboré, Jacques, additional, Camara, Mamadou, additional, Cooper, Anneli, additional, Tait, Andy, additional, Jamonneau, Vincent, additional, Bucheton, Bruno, additional, Berriman, Matt, additional, and MacLeod, Annette, additional
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- 2016
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27. Author response: Population genomics reveals the origin and asexual evolution of human infective trypanosomes
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Weir, William, primary, Capewell, Paul, additional, Foth, Bernardo, additional, Clucas, Caroline, additional, Pountain, Andrew, additional, Steketee, Pieter, additional, Veitch, Nicola, additional, Koffi, Mathurin, additional, De Meeûs, Thierry, additional, Kaboré, Jacques, additional, Camara, Mamadou, additional, Cooper, Anneli, additional, Tait, Andy, additional, Jamonneau, Vincent, additional, Bucheton, Bruno, additional, Berriman, Matt, additional, and MacLeod, Annette, additional
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- 2015
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28. The Paralogous Transcription Factors Stp1 and Stp2 of Candida albicansHave Distinct Functions in Nutrient Acquisition and Host Interaction
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Miramón, Pedro, Pountain, Andrew W., van Hoof, Ambro, and Lorenz, Michael C.
- Abstract
Nutrient acquisition is a central challenge for all organisms. For the fungal pathogen Candida albicans, utilization of amino acids has been shown to be critical for survival, immune evasion, and escape, while the importance of catabolism of host-derived proteins and peptides in vivois less well understood. Stp1 and Stp2 are paralogous transcription factors (TFs) regulated by the Ssy1-Ptr3-Ssy5 (SPS) amino acid sensing system and have been proposed to have distinct, if uncertain, roles in protein and amino acid utilization.
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- 2020
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29. Drug resistance and treatment failure in leishmaniasis: A 21st century challenge
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Alicia Ponte-Sucre, Francisco Gamarro, Jean-Claude Dujardin, Raquel García-Hernández, Andrew W. Pountain, Rogelio López-Vélez, Michael P. Barrett, Roy Mwenechanya, Barbara Papadopoulou, Canadian Institutes of Health Research, Junta de Andalucía, Wellcome Trust, Alexander von Humboldt Foundation, Ministerio de Economía y Competitividad (España), Pountain, Andrew W., and Pountain, Andrew W.[0000-0001-9651-5145]
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Antimony ,0301 basic medicine ,Leishmania Donovani ,ABC-TRANSPORTER MRPA ,Epidemiology ,Meglumine antimoniate ,Drug Resistance ,Review ,MEGLUMINE ANTIMONIATE ,Drug resistance ,Antimony-resistant ,Zoonoses ,Medicine and Health Sciences ,Treatment Failure ,Leishmaniasis ,Protozoans ,Leishmania ,Molecular Epidemiology ,biology ,Pharmaceutics ,lcsh:Public aspects of medicine ,Eukaryota ,3. Good health ,Chemistry ,PROTOZOAN PARASITE LEISHMANIA ,Infectious Diseases ,Physical Sciences ,Leishmaniasis, Visceral ,Drug Therapy, Combination ,Neglected Tropical Diseases ,Chemical Elements ,medicine.drug ,medicine.medical_specialty ,lcsh:Arctic medicine. Tropical medicine ,lcsh:RC955-962 ,Sodium stibogluconate ,Phosphorylcholine ,education ,Antiprotozoal Agents ,Leishmania donovani ,Leishmaniasis, Cutaneous ,Microbiology ,SODIUM STIBOGLUCONATE ,03 medical and health sciences ,Drug Therapy ,Cutaneous leishmaniasis ,Microbial Control ,Amphotericin B ,Parasitic Diseases ,medicine ,Humans ,Intensive care medicine ,Biology ,Pharmacology ,Miltefosine ,Protozoan Infections ,MILTEFOSINE RESISTANCE ,business.industry ,Organisms ,Public Health, Environmental and Occupational Health ,Biology and Life Sciences ,lcsh:RA1-1270 ,Tropical Diseases ,medicine.disease ,biology.organism_classification ,Parasitic Protozoans ,DONOVANI PROMASTIGOTES ,030104 developmental biology ,Visceral leishmaniasis ,VISCERAL LEISHMANIASIS ,Antimicrobial Resistance ,Human medicine ,AMPHOTERICIN-B RESISTANCE ,business - Abstract
Reevaluation of treatment guidelines for Old and New World leishmaniasis is urgently needed on a global basis because treatment failure is an increasing problem. Drug resistance is a fundamental determinant of treatment failure, although other factors also contribute to this phenomenon, including the global HIV/AIDS epidemic with its accompanying impact on the immune system. Pentavalent antimonials have been used successfully worldwide for the treatment of leishmaniasis since the first half of the 20th century, but the last 10 to 20 years have witnessed an increase in clinical resistance, e.g., in North Bihar in India. In this review, we discuss the meaning of “resistance” related to leishmaniasis and discuss its molecular epidemiology, particularly for Leishmania donovani that causes visceral leishmaniasis. We also discuss how resistance can affect drug combination therapies. Molecular mechanisms known to contribute to resistance to antimonials, amphotericin B, and miltefosine are also outlined., Research reported in this publication was supported by the Canadian Institutes of Health Research operating grant MOP-12182 awarded to BP; the Spanish Grant Proyecto de Excelencia, Junta de Andalucía Ref. CTS-7282 awarded to FG; the Spanish Grant SAF2015-68042-R awarded to FG; the Wellcome Trust (104111/Z/14/Z) awarded to MPB; and the Alexander von Humboldt Foundation, Germany awarded to APS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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- 2017
30. Quorum-sensing agr system of Staphylococcus aureus primes gene expression for protection from lethal oxidative stress.
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Podkowik M, Perault AI, Putzel G, Pountain A, Kim J, Dumont A, Zwack E, Ulrich RJ, Karagounis TK, Zhou C, Haag AF, Shenderovich J, Wasserman GA, Kwon J, Chen J, Richardson AR, Weiser JN, Nowosad CR, Lun DS, Parker D, Pironti A, Zhao X, Drlica K, Yanai I, Torres VJ, and Shopsin B
- Abstract
The agr quorum-sensing system links Staphylococcus aureus metabolism to virulence, in part by increasing bacterial survival during exposure to lethal concentrations of H
2 O2 , a crucial host defense against S. aureus . We now report that protection by agr surprisingly extends beyond post-exponential growth to the exit from stationary phase when the agr system is no longer turned on. Thus, agr can be considered a constitutive protective factor. Deletion of agr increased both respiration and fermentation but decreased ATP levels and growth, suggesting that Δ agr cells assume a hyperactive metabolic state in response to reduced metabolic efficiency. As expected from increased respiratory gene expression, reactive oxygen species (ROS) accumulated more in the agr mutant than in wild-type cells, thereby explaining elevated susceptibility of Δ agr strains to lethal H2 O2 doses. Increased survival of wild-type agr cells during H2 O2 exposure required sodA , which detoxifies superoxide. Additionally, pretreatment of S. aureus with respiration-reducing menadione protected Δ agr cells from killing by H2 O2 . Thus, genetic deletion and pharmacologic experiments indicate that agr helps control endogenous ROS, thereby providing resilience against exogenous ROS. The long-lived "memory" of agr -mediated protection, which is uncoupled from agr activation kinetics, increased hematogenous dissemination to certain tissues during sepsis in ROS-producing, wild-type mice but not ROS-deficient (Nox2-/- ) mice. These results demonstrate the importance of protection that anticipates impending ROS-mediated immune attack. The ubiquity of quorum sensing suggests that it protects many bacterial species from oxidative damage., Competing Interests: Potential competing interests. B.S. has consulted for Basilea Pharmaceutica. V.J.T. has received honoraria from Pfizer and MedImmune, and is an inventor on patents and patent applications filed by New York University, which are currently under commercial license to Janssen Biotech Inc. Janssen Biotech Inc. provides research funding and other payments associated with a licensing agreement. All other authors: no competing interests declared.- Published
- 2024
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31. Transcription-replication interactions reveal principles of bacterial genome regulation.
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Pountain AW, Jiang P, Yao T, Homaee E, Guan Y, Podkowik M, Shopsin B, Torres VJ, Golding I, and Yanai I
- Abstract
Organisms determine the transcription rates of thousands of genes through a few modes of regulation that recur across the genome
1 . These modes interact with a changing cellular environment to yield highly dynamic expression patterns2 . In bacteria, the relationship between a gene's regulatory architecture and its expression is well understood for individual model gene circuits3,4 . However, a broader perspective of these dynamics at the genome-scale is lacking, in part because bacterial transcriptomics have hitherto captured only a static snapshot of expression averaged across millions of cells5 . As a result, the full diversity of gene expression dynamics and their relation to regulatory architecture remains unknown. Here we present a novel genome-wide classification of regulatory modes based on each gene's transcriptional response to its own replication, which we term the Transcription-Replication Interaction Profile (TRIP). We found that the response to the universal perturbation of chromosomal replication integrates biological regulatory factors with biophysical molecular events on the chromosome to reveal a gene's local regulatory context. While the TRIPs of many genes conform to a gene dosage-dependent pattern, others diverge in distinct ways, including altered timing or amplitude of expression, and this is shaped by factors such as intra-operon position, repression state, or presence on mobile genetic elements. Our transcriptome analysis also simultaneously captures global properties, such as the rates of replication and transcription, as well as the nestedness of replication patterns. This work challenges previous notions of the drivers of expression heterogeneity within a population of cells, and unearths a previously unseen world of gene transcription dynamics., Competing Interests: Competing interests: The authors declare no competing interests.- Published
- 2023
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32. Genomic instability at the locus of sterol C24-methyltransferase promotes amphotericin B resistance in Leishmania parasites.
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Pountain AW, Weidt SK, Regnault C, Bates PA, Donachie AM, Dickens NJ, and Barrett MP
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- Animals, Antiprotozoal Agents pharmacology, Drug Resistance, Gene Expression Regulation, Enzymologic, Humans, Methyltransferases metabolism, Amphotericin B pharmacology, Genomic Instability, Leishmania mexicana drug effects, Leishmania mexicana genetics, Methyltransferases genetics
- Abstract
Amphotericin B is an increasingly important tool in efforts to reduce the global disease burden posed by Leishmania parasites. With few other chemotherapeutic options available for the treatment of leishmaniasis, the potential for emergent resistance to this drug is a considerable threat. Here we characterised four novel amphotericin B-resistant Leishmania mexicana lines. All lines exhibited altered sterol biosynthesis, and hypersensitivity to pentamidine. Whole genome sequencing demonstrated resistance-associated mutation of the sterol biosynthesis gene sterol C5-desaturase in one line. However, in three out of four lines, RNA-seq revealed loss of expression of sterol C24-methyltransferase (SMT) responsible for drug resistance and altered sterol biosynthesis. Additional loss of the miltefosine transporter was associated with one of those lines. SMT is encoded by two tandem gene copies, which we found to have very different expression levels. In all cases, reduced overall expression was associated with loss of the 3' untranslated region of the dominant gene copy, resulting from structural variations at this locus. Local regions of sequence homology, between the gene copies themselves, and also due to the presence of SIDER1 retrotransposon elements that promote multi-gene amplification, correlate to these structural variations. Moreover, in at least one case loss of SMT expression was not associated with loss of virulence in primary macrophages or in vivo. Whilst such repeat sequence-mediated instability is known in Leishmania genomes, its presence associated with resistance to a major antileishmanial drug, with no evidence of associated fitness costs, is a significant concern., Competing Interests: The authors have declared that no competing interests exist.
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- 2019
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33. Drug resistance and treatment failure in leishmaniasis: A 21st century challenge.
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Ponte-Sucre A, Gamarro F, Dujardin JC, Barrett MP, López-Vélez R, García-Hernández R, Pountain AW, Mwenechanya R, and Papadopoulou B
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- Amphotericin B pharmacology, Amphotericin B therapeutic use, Antiprotozoal Agents pharmacology, Antiprotozoal Agents therapeutic use, Drug Therapy, Combination, Humans, Leishmania genetics, Leishmania donovani drug effects, Leishmania donovani pathogenicity, Leishmaniasis immunology, Leishmaniasis parasitology, Leishmaniasis, Cutaneous drug therapy, Leishmaniasis, Visceral drug therapy, Leishmaniasis, Visceral parasitology, Molecular Epidemiology, Phosphorylcholine analogs & derivatives, Phosphorylcholine pharmacology, Phosphorylcholine therapeutic use, Treatment Failure, Drug Resistance, Leishmania drug effects, Leishmania pathogenicity, Leishmaniasis drug therapy
- Abstract
Reevaluation of treatment guidelines for Old and New World leishmaniasis is urgently needed on a global basis because treatment failure is an increasing problem. Drug resistance is a fundamental determinant of treatment failure, although other factors also contribute to this phenomenon, including the global HIV/AIDS epidemic with its accompanying impact on the immune system. Pentavalent antimonials have been used successfully worldwide for the treatment of leishmaniasis since the first half of the 20th century, but the last 10 to 20 years have witnessed an increase in clinical resistance, e.g., in North Bihar in India. In this review, we discuss the meaning of "resistance" related to leishmaniasis and discuss its molecular epidemiology, particularly for Leishmania donovani that causes visceral leishmaniasis. We also discuss how resistance can affect drug combination therapies. Molecular mechanisms known to contribute to resistance to antimonials, amphotericin B, and miltefosine are also outlined.
- Published
- 2017
- Full Text
- View/download PDF
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