title: Glycine metabolism and anti-oxidative defence mechanisms in Pseudomonas fluorescens.
abstract: The role of metabolism in anti-oxidative defence is only now beginning to emerge. Here, we show that the nutritionally-versatile microbe, Pseudomonas fluorescens, reconfigures its metabolism in an effort to generate NADPH, ATP and glyoxylate in order to fend off oxidative stress. Glyoxylate was produced predominantly via the enhanced activities of glycine dehydrogenase-NADP(+) (GDH), glycine transaminase (GTA) and isocitrate lyase (ICL) in a medium exposed to hydrogen peroxide (H₂O₂). This ketoacid was utilized to produce ATP by substrate-level phosphorylation and to neutralize reactive oxygen species with the concomitant formation of formate. The latter was also a source of NADPH, a process mediated by formate dehydrogenase-NADP(+) (FDH). The increased activities of phosphoenolpyruvate carboxylase (PEPC) and pyruvate orthophosphate dikinase (PPDK) worked in tandem to synthesize ATP in the H₂O₂-challenged cells that had markedly diminished capacity for oxidative phosphorylation. These metabolic networks provide an effective means of combating ROS and reveal therapeutic targets against microbes resistant to oxidative stress.
authors: Faculty of Science and Engineering, Laurentian University, Sudbury, ON, Canada.
authors: Azhar
authors: A
authors: Alhasawi
authors: Faculty of Science and Engineering, Laurentian University, Sudbury, ON, Canada.
authors: Zachary
authors: Z
authors: Castonguay
authors: Faculty of Science and Engineering, Laurentian University, Sudbury, ON, Canada.
authors: Nishma D
authors: ND
authors: Appanna
authors: Faculty of Science and Engineering, Laurentian University, Sudbury, ON, Canada.
authors: Christopher
authors: C
authors: Auger
authors: Faculty of Science and Engineering, Laurentian University, Sudbury, ON, Canada. Electronic address: vappanna@laurentian.ca.
authors: Vasu D
authors: VD
authors: Appanna
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011551:Pseudomonas fluorescens / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D009243:NAD; D009249:NADP; D005998:Glycine
keywords: ATP; Antioxidant; Glyoxylate; Metabolism; Oxidative stress