Aspartate metabolism and pyruvate homeostasis triggered by oxidative stress in Pseudomonas fluorescens: a functional metabolomic study
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There is mounting evidence that metabolic reprogramming is critical for the survival of organisms exposed to changing and stressed environments. Using the soil microbe Pseudomonas fluorescens as a model system, we demonstrate that the metabolic networks aimed at the conversion of aspartate into pyruvate are enhanced in the presence of hydrogen peroxide (H2O2). The metabolites pyruvate, oxaloacetate and acetate were increased in the treated cultures as measured by HPLC. Enzymes such as aspartate transaminase and phosphoenolpyruvate carboxylase (PEPC) that mediate the conversion of aspartate to phosphoenolpyruvate (PEP) were up-regulated. This high-energy phosphate was readily converted into ATP, a process facilitated by the increased activity of pyruvate orthophosphate dikinase (PPDK) and phosphoenolpyruvate synthase (PEPS) as oxidative phosphorylation was severely compromised. The ensuing formation of pyruvate readily detoxified reactive oxygen species with the concomitant formation of acetate. This H2O2-induced metabolic reconfiguration not only helps generate the antioxidants necessary to thwart oxidative stress but also powers the formation of energy.
KeywordsPyruvate Antioxidant Metabolic networks Pyruvate synthase Energy
Cell free extract
Glucose 6-phosphate dehydrogenase
Pyruvate orthophosphate dikinase
Reactive oxygen species
Reduced nicotinamide adenine dinucleotide phosphate
This study was funded by Laurentian University and the Northern Ontario Heritage Fund. Azhar Alhasawi is a recipient of funding from the Ministry of Higher Education of Saudi Arabia.
Compliance with ethical standards
Conflict of Interest
All authors declare that they have no conflict of interest.
Research involving Human and Animal Rights
This article does not contain any studies with human participants or animals performed by any of the authors.
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