title: Phospho-transfer networks and ATP homeostasis in response to an ineffective electron transport chain in Pseudomonas fluorescens.
abstract: Although oxidative stress is known to impede the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, the nutritionally-versatile microbe, Pseudomonas fluorescens has been shown to proliferate in the presence of hydrogen peroxide (H2O2) and nitrosative stress. In this study we demonstrate the phospho-transfer system that enables this organism to generate ATP was similar irrespective of the carbon source utilized. Despite the diminished activities of enzymes involved in the TCA cycle and in the electron transport chain (ETC), the ATP levels did not appear to be significantly affected in the stressed cells. Phospho-transfer networks mediated by acetate kinase (ACK), adenylate kinase (AK), and nucleoside diphosphate kinase (NDPK) are involved in maintaining ATP homeostasis in the oxidatively-challenged cells. This phospho-relay machinery orchestrated by substrate-level phosphorylation is aided by the up-regulation in the activities of such enzymes like phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPDK), and phosphoenolpyruvate synthase (PEPS). The enhanced production of phosphoenolpyruvate (PEP) and pyruvate further fuel the synthesis of ATP. Taken together, this metabolic reconfiguration enables the organism to fulfill its ATP need in an O2-independent manner by utilizing an intricate phospho-wire module aimed at maximizing the energy potential of PEP with the participation of AMP.
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E 2C6, Canada.
authors.forename: V P
authors.initials: VP
authors.lastname: Appanna
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E 2C6, Canada.
authors.forename: A A
authors.initials: AA
authors.lastname: Alhasawi
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E 2C6, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Auger
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E 2C6, Canada.
authors.forename: S C
authors.initials: SC
authors.lastname: Thomas
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E 2C6, Canada. Electronic address: vappanna@laurentian.ca.
authors.forename: V D
authors.initials: VD
authors.lastname: Appanna
mesh_terms: D000249:Adenosine Monophosphate / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry*; D002952:Citric Acid Cycle; D003720:Densitometry; D004579:Electron Transport; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D010084:Oxidation-Reduction; D010085:Oxidative Phosphorylation; D018384:Oxidative Stress; D010100:Oxygen / Q000737:chemistry; D010728:Phosphoenolpyruvate / Q000737:chemistry; D010766:Phosphorylation; D017866:Phosphotransferases (Paired Acceptors) / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000378:metabolism*; D011772:Pyruvate, Orthophosphate Dikinase / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D008055:Lipids; D017382:Reactive Oxygen Species; D000249:Adenosine Monophosphate; D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D017866:Phosphotransferases (Paired Acceptors); D011772:Pyruvate, Orthophosphate Dikinase; C022509:pyruvate, water dikinase; D010100:Oxygen
keywords: ATP homeostasis; Bioenergetics; Electron transport chain; Phospho-transfer networks; Phosphoenolpyruvate; Pyruvate