Please use this identifier to cite or link to this item: https://zone.biblio.laurentian.ca/handle/10219/3924
Full metadata record
DC FieldValueLanguage
dc.contributor.authorLegendre, Félix-
dc.date.accessioned2022-07-27T14:09:17Z-
dc.date.available2022-07-27T14:09:17Z-
dc.date.issued2022-06-28-
dc.identifier.urihttps://zone.biblio.laurentian.ca/handle/10219/3924-
dc.description.abstractSulfur plays an essential role in oxidative homeostasis due to its participation in sulfhydryl groups (SH). A disruption of this vital nutrient is known to promote oxidative stress and activates a plethora of anti-oxidative strategies. Phosphate, a micronutrient that is part of adenosine triphosphate (ATP), the main molecule used as energy and other macromolecules in living cells. The stress response to sulfur and phosphate deficiency in Pseudomonas fluorescens was investigated with emphasis on ROS detoxification, and energy production. Metabolite profiling was performed by High Performance Liquid Chromatography (HPLC), enzymatic analysis was done using Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) and gene expression assessment of targeted genes was performed with SYBR-Green real-time PCR (qPCR). When cultured in a sulfur-deficient medium with glutamine as the sole carbon and nitrogen source, the microbe reconfigures its metabolism aimed at the enhanced synthesis of NADPH, an antioxidant and the limited production of NADH, a pro-oxidant. The up-regulation of isocitrate dehydrogenase (ICDH)-NADP+ dependent in the soluble fraction of the cells obtained from the S-deficient media results in enhanced NADPH synthesis. This reaction is aided by the concomitant increase in NAD kinase (NADK) activity. The latter converts NAD+ into NADP+ in the presence of ATP. Additionally, the microbe reprograms its metabolic pathways to produce KG and regenerate this keto-acid from succinate, a by-product of ROS detoxification. Succinate semialdehyde dehydrogenase (SSADH) and KG decarboxylase (KDC) work in partnership to synthesize KG. This process is further aided by the increased activity of the enzymes glutamate decarboxylase (GDC) and γ-amino-butyrate transaminases (GABA-T). Taken together, the data point to a metabolic network involving isocitrate, KG, and ICDH that converts NADH into NADPH in P. fluorescens subjected to a S-deprived environment. Finally, when cultured in low phosphate environments, the microbe can produce ATP via substrate level phosphorylation (SLP), in a mechanism involving the reductive isocitrate dehydrogenase (ICDH-NADH), isocitrate lyase (ICL), malate synthase (MS) as well as phosphoenol pyruvate carboxylase (PEPC), phosphoenol pyruvate synthase (PEPS) and pyruvate phosphate dikinase (PPDK). This metabolic reprogramming ensures the survival of the microbe and reveals the central role metabolism plays in cellular adaptation to abiotic stress.en_US
dc.language.isoenen_US
dc.subjectBiochemistryen_US
dc.subjectmicrobiologyen_US
dc.subjectmetabolismen_US
dc.subjectTCA cycleen_US
dc.subjectabiotic stressen_US
dc.subjectcellular stressen_US
dc.subjectsulfur starvationen_US
dc.subjectphosphate starvationen_US
dc.subjectglutamineen_US
dc.subjectenergyen_US
dc.subjectATPen_US
dc.subjectoxidative stressen_US
dc.subjectsuccinateen_US
dc.subjectα-ketoglutarateen_US
dc.subjectNADPHen_US
dc.titleUnraveling the metabolic networks involved in the utilization of L-glutamine in Pseudomonas fluorescens exposed to nutritional stressen_US
dc.typeThesisen_US
dc.description.degreeDoctor of Philosophy (PhD) in Biomolecular Sciencesen_US
dc.publisher.grantorLaurentian University of Sudburyen_US
Appears in Collections:Biomolecular Sciences - Doctoral Theses

Files in This Item:
File Description SizeFormat 
Felix Legendre BMS PhD Thesis final.pdf6.94 MBAdobe PDFView/Open


Items in LU|ZONE|UL are protected by copyright, with all rights reserved, unless otherwise indicated.