Browsing by Author "Turner, Raymond J."
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- ItemOpen AccessA mucosal surface model of pseudomonas aeruginosa infections(2012) Nelson, Lisa K.; Ceri, Howard; Turner, Raymond J.In the human body, mucosal sites such as the lungs, eyes, gastrointestinal tract and urinary tract are often the target of bacterial infections. One of the most notorious bacterial species known to infect mucosal surfaces is the opportunistic pathogen Pseudomonas aeruginosa. As such, there has been much research devoted to studying the mechanisms by which P. aeruginosa infects these surfaces, particularly how it causes chronic infections as these infections are problematic and difficult to eradicate. However, because P. aeruginosa is an opportunistic pathogen - in that it typically causes infection of mucosa! sites when they are compromised by disease, injury, or implanted medical devices - it has proved difficult to model infections by these bacteria. Consequently, in this work, we hypothesized that we could develop a novel model using the rat prostate for studying acute and chronic P. aeruginosa infections at mucosal surfaces. Unlike current mammalian models of chronic infections, this model has an advantage: chronic infections can easily form at the prostate mucosal surface without foreign body assistance. Therefore, using this model, we were able to study how chronic P. aeruginosa infections were influenced by processes that occur within the biofilm - a mode of adherent bacterial growth that is resistant to clearance. We found that signalling via quorum sensing was required to maintain a chronic infection, but this was likely due to its role in biofilm function rather than formation. We also showed, for the first time, that generation of variants associated with biofilm growth occurred in vivo using similar genetic pathways previously identified in vitro. Furthermore, we ascertained that the generation of variants could be critical for maintaining an infection, and that a heterogeneous population of variants was produced during mucosal surface infections. Finally, we expanded on the utility of our model and showed that diversity via multi-isolate infections affected chronic P. aeruginosa virulence. Thus, altogether, using our novel prostate model we were able to determine that signalling and diversity generation were important for chronic P. aeruginosa infections at mucosa! surfaces. These findings should have important implications for the development of better therapeutics against P. aeruginosa.
- ItemOpen AccessAn exploration of microbial response to stressors with Prof. Claudio C. Vásquez Guzmán(2022-08-06) Seeger, Michael; Turner, Raymond J.; González, Mauricio
- ItemOpen AccessBiofilm physiology and cyclic-di-gmp in escherichia coli(2012) Stan, Michelle A.; Turner, Raymond J.; Ceri, Howard
- ItemOpen AccessBiophysical investigations into the Escherichia coli small multidrug efflux protein EmrE and its binding to ligand(2005) Sikora, Curtis Wayne; Turner, Raymond J.
- ItemOpen AccessCharacterization and development of tryptophan photochemistry with halogenated hydrocarbons for protein chemistry applications(2007) Ladner, Carol Lynn; Turner, Raymond J.; Edwards, Robert A.
- ItemOpen AccessCharacterization of site-directed mutants of the Haemophilus influenzae ferric-ion binding protein A(2002) Shouldice, Stephen R.; Turner, Raymond J.
- ItemOpen AccessCharacterization of the twin-arginine leader binding protein, DmsD(2005) Papish, Andriyka Lydia Maria; Turner, Raymond J.
- ItemOpen AccessChemical, Physiological and Metabolic Interactions between Pseudomonas, Metals and Environmental Nutrients(2017) Booth, Sean C.; Turner, Raymond J.; Weljie, Aalim; Gieg, Lisa; Turner, Raymond J.; Eltis, Lindsay; DeVinney, RebekahEnvironmental pollution is one of the major problems facing humanity. Bacteria are capable of removing pollutants from the environment through their metabolic activities. This works for organic pollutants, but metals inhibit the degradation process. Pseudomonas pseudoalcaligenes KF707 is a bacterium that is resistant to metals and is able to degrade pollutants such as polychlorinated biphenyls. In this thesis I present how interactions between the bacterium, its environment and metals affect the bacterium’s physiology and metabolism of biphenyl. Chemical interactions with environmental components affect the toxicity of metals towards bacteria. By examining the tolerance of Pseudomonas species towards copper and aluminium in different media compositions I found that metal bioavailability and carbon source quality had a strong influence on the amount of metal they could withstand. Building on these data, I used metabolomics to understand how metals interfere with organic pollutant degradation. By quantifying the small molecules used and produced by the bacterial cell I was able to determine that metal toxicity is exacerbated by the oxidative stress of metabolizing an organic pollutant. P. pseudoalcaligenes KF707 can swim towards biphenyl but it was unknown how. By deleting genes that were expected to be involved in energy-taxis, a process that allows bacteria to swim to metabolizable carbon sources, I found that this was not how KF707 swims towards biphenyl. I did discover that some unexpected genes were involved in energy-taxis and also that the primary gene for this behavior, Aer, is actually a family of receptors with variable phylogenetic distribution in the genus Pseudomonas. These results provide new insight into the interactions between a bacterium and the nutrients and stressors in their environment.
- ItemOpen AccessThe efficacy of different antimicrobial metals at preventing the formation of, and eradicating bacterial biofilms of pathogenic indicator strains.(Nature, 2017-02-15) Gugala, Natalie; Lemire, Joe A.; Turner, Raymond J.The emergence of multidrug resistant pathogens and the prevalence of biofilm-related infections have generated a demand for alternative antimicrobial therapies. Metals have not been explored in adequate detail for their capacity to combat infectious disease. Metal compounds can now be found in textiles, medical devices, and disinfectants – yet, we know little about their efficacy against specific pathogens. To help fill this knowledge gap, we report on the antimicrobial and antibiofilm activity of seven metals; silver, copper, titanium, gallium, nickel, aluminum and zinc against three bacterial strains, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. In order to evaluate the capacity of metal ions to prevent the growth of, and eradicate biofilms and planktonic cells, bacterial cultures were inoculated in the Calgary Biofilm Device (MBEC™) in the presence the metal salts. Copper, gallium, and titanium were capable of preventing planktonic and biofilm growth, and eradicating established biofilms of all tested strains. Further, we observed that the efficacies of the other tested metal salts displayed variable efficacy against the tested strains. Further, contrary to the enhanced resistance anticipated from bacterial biofilms, particular metal salts were observed to be more effective against biofilm communities versus planktonic cells. In this study, we have demonstrated that the identity of the bacterial strain must be considered prior to treatment with a particular metal ion. Consequently, as the use of metal ions as antimicrobial agents to fight multidrug resistant and biofilm related infections increases, we must aim for more selective deployment in a given infectious setting.
- ItemOpen AccessEvaluating the Metal Tolerance Capacity of Oil Sands Tailings Microbes, and their Ability to Degrade Naphthenic Acids While Attached to Biochar(2016) Frankel, Mathew; Turner, Raymond J.; Gieg, Lisa; Layzell, DavidAlberta’s oil sands process water (OSPW) was used herein as a case to investigate co-contaminated wastewater treatment; naphthenic acids (NAs, implicated for OSPW toxicity) and metals have been reported in OSPW. This thesis sought to evaluate the metal tolerances of a native OSPW microbial community, and the effect of OSPW-specific metals on their ability to degrade NAs. Furthermore, this work focused on enhancing OSPW treatment by growing these NA-degrading communities on an engineered adsorbent, biochar, under the hypothesis that combining the effects of biochar with attached OSPW microbes would be more effective at contaminant removal than either independent approach. Metal susceptibility experiments with the OSPW community demonstrated elevated tolerances to OSPW metals. Microbial-biochar work showed biochar NA removal was enhanced by microbial degradation, with mixed results in the effects of metal co-contamination on biodegradation with each biochar. Metal immobilization was improved by microbial attachment to adsorbents, regardless of biochar assayed.
- ItemOpen AccessGtp interactions with the system specific chaperone, dmsd(2011) Tran, Vy An; Turner, Raymond J.
- ItemOpen AccessIdentification of the Docking Regions within the TatBC Receptor of the Twin‐Arginine Translocation System for the Redox Enzyme Maturation Protein Chaperones in Escherichia coli(2015-04-06) Kuzniatsova, Lalita; Turner, Raymond J.The Twin-arginine translocation pathway (Tat) serves for targeting and translocation of fully folded proteins across cytoplasmic membranes in bacterial and plant chloroplast thylakoid membranes. In Escherichia coli there are three core components of the Tat system: TatA, TatB, and TatC, where TatB and TatC subunits form the receptor complex for Tat-bound proteins and TatA monomers form the translocation pore itself. Redox Enzyme Maturation Proteins (REMPs) are system specific chaperones, which play significant roles in the maturation of Tat dependent respiratory enzymes. DmsD chaperone – the REMP for dimethyl sulfoxide reductase in E. coli – is known to interact with TatBC complex from previous research. Here in vivo and in vitro techniques were used to investigate interactions between REMPs and the cytoplasmic domains of TatBC proteins. Ten REMPs from E. coli were screened for in vivo interactions with the TatBC using Bacterial adenylate cyclase two-hybrid assay, the results demonstrated that all but the formate dehydrogenase REMPs play a crucial role in targeting the substrates - respiratory enzymes - to the Tat system. In vitro peptide assay and Isothermal titration calorimetry was then implemented in order to determine the regions within TatB and TaC, responsible for the REMPs docking.
- ItemOpen AccessInvestigations into the interactome of the redox enzyme maturation protein, dmsd, through various protein-protein interaction methodologies(2005) Howell, Jenika M.; Turner, Raymond J.
- ItemOpen AccessInvestigations into the phenotype of the SugE, a class of the small multidrug resistance protein family(2002) Son, Mike Seong; Turner, Raymond J.
- ItemOpen AccessIon Modulation in Secondary Transporters(2016-02-02) Zdravkovic, Igor; Noskov, Sergei; Edwards, Robert Allan; Tieleman, Peter; Turner, Raymond J.; MacCallum, Justin Laine; Casey, Joseph RomanMolecular transport across the cell membrane is an important and highly regulated process. Secondary transporters are a large family of integral membrane proteins responsible for mediating molecular exchange. Pre-existing ion gradients are utilized to drive secondary transport. Our focus was on the solute carrier (SLC) family of secondary transporters, specifically those that utilize Na+ to drive transport. The SLC family can be further classified as a sodium substrate symporter (SSS). Specifically, we focused on the human serotonin and dopamine transporters (SLC6) and iodide symporters (SLC5). The sodium electrochemical potential is coupled to the energetically unfavourable transport of the substrate. This yields a net favourable translocation of the substrate and co-transported ions. Little structural information is available on the SSS family transporters and even less when only the human variants are considered. This prompted an attempt to predict human protein structures using the available data from bacterial homologues to fill the knowledge gap. The methodology was based on the X-ray structures of the leucine transporter (LeuT) and sodium galactose transporter (vSGLT). Through our structural alignments we were able to identify the ion binding sites. With the help of Glide docking software, we successfully identified substrate and inhibitors binding sites. Molecular dynamics were used to simulate biologically relevant systems and find the forces driving substrate and ion binding. Our computational biochemistry approach has proven to be a reliable method to study the transport and substrate interactions. In addition, our collaborative efforts successfully merged theoretical and experimental science.
- ItemOpen AccessMetabolomic and lipidomic profiling of the effect of edelfosine treatment on Saccharomyces cerevisiae(2014-01-28) Tambellini, Nicolas Pietro; Turner, Raymond J.Edelfosine is a lysophosphatidylcholine analogue and the prototype of a new class of compounds being investigated for their potential as highly selective chemotherapeutic agents. Edelfosine has been implicated as affecting numerous different metabolic pathways, though its mechanism of action is not well understood at this time. To gain further insight into edelfosine’s mechanism of action we carried out mass spectrometry based metabolomic and lipidomic profiling of yeast exposed to a cytostatic concentrations of edelfosine. Using multivariate projection methods and statistical analysis, we determined that edelfosine exerts a significant effect on many aspects of yeast metabolism. Metabolic pathways that were found to be perturbed included those involved with amino acid metabolism, sugar metabolism, the TCA cycle, fatty acid biosynthesis, sphingolipid metabolism, glycerophospholipid metabolism and glycerolipid metabolism. It was also observed that there is a kinetic difference in the response of polar and non-polar metabolites to edelfosine treatment in yeast.
- ItemOpen AccessMetabolomics reveals differences of metal Toxicity in cultures of Pseudomonas pseudoalcaligenes KF707 grown on different carbon sources(Frontiers, 2015-08-17) Booth, Sean C.; Weljie, Aalim M.; Turner, Raymond J.Co-contamination of metals and organic pollutants is a global problem as metals interfere with the metabolism of complex organics by bacteria. Based on a prior observation that metal tolerance was altered by the sole carbon source being used for growth, we sought to understand how metal toxicity specifically affects bacteria using an organic pollutant as their sole carbon source. To this end metabolomics was used to compare cultures of Pseudomonas pseudoalcaligenes KF707 grown on either biphenyl or succinate as the sole carbon source in the presence of either aluminum or copper. Using multivariate statistical analysis it was found that the metals caused perturbations to more cellular processes in the cultures grown on biphenyl than those grown on succinate. Aluminum induced many changes that were indicative of increased oxidative stress as metabolites involved in DNA damage and protection, the Krebs cycle and the production of NADPH were altered. Copper also caused metabolic changes that were indicative of similar stress, as well as appearing to disrupt other key enzymes such as fumarase. Additionally, both metals caused the accumulation of biphenyl degradation intermediates indicating that they interfered with biphenyl metabolism. Together these results provide a basic understanding of how metal toxicity specifically affects bacteria at a biochemical level during the degradation of an organic pollutant and implicate the catabolism of this carbon source as a major factor that exacerbates metal toxicity.
- ItemOpen AccessMethodological Analysis of an Improved Gluten Quantitation Aptamer-based Biosensor(2022-09-22) Kuri Martinez, Juan Carlos; Yadid-Pecht, Orly; Turner, Raymond J.; Murari, Kartikeya; Birss, Viola IngridFluorescence resonance energy transfer based aptamer are currently being studied in many research groups due to their potential contribution as an alternative gluten standard for gluten- quantitation. The current gold standard withholds critical limitations due to the nature of the system, hence this aptamer-based sensor (or aptasensor for short) application represents one of the alternatives; yet, drawbacks such as low signal-to-noise ratio and reliability are in the scope of research groups aiming to overcome them. In this study, multiple variations of the protocol are assessed based on correctly classifying food samples as their actual concentration of gluten, this is coined as the accuracy of the biosensor. The study also aims to overcome the current limitation of the gold standard in fermented samples by including soy sauce and malt vinegar in the tests. And different additives aiming to help overcoming the limitation were implemented into the protocol and assessed. This approach allowed the biosensor to classify the products with 98.28% of accuracy, and 0% of error in classifying gluten-rich products (false-negatives) within the first 3 days of bioassay preparation; yet, this bioassay needs to be studied further as only 18 different off-the-shelf products were tested (over 800 tests in total). Additionally, after the first week, false-negatives increased to around 5% and remained that way until the end of the first month. The cause of this relies mostly on the decomposition of the conjugate reduced graphene oxide and polyethylene glycol that are implemented in the system. This implies that further research aiming solely at additives or alternative reagents that increase the lifespan or stability of the conjugate would augment the overall performance.
- ItemOpen AccessMulti-metal resistance and tolerance in pseudomonas fluorescens: contributions of metabolism, morpholigcal variation and the gac/rsm signal transduction system(2010) Workentine, Matthew L.; Turner, Raymond J.; Ceri, Howard
- ItemOpen AccessMultimetal resistance and tolerance in microbial biofilms(2008) Harrison, Joe J.; Turner, Raymond J.; Ceri, Howard