title: Zinc toxicity and ATP production in Pseudomonas fluorescens.
abstract: OBJECTIVE
  To identify the molecular networks in Pseudomonas fluorescens that convey resistance to toxic concentrations of Zn, a common pollutant and hazard to biological systems.
  
  
  RESULTS
  Pseudomonas fluorescens strain ATCC 13525 was cultured in growth medium with millimolar concentrations of Zn. Enzymatic activities and metabolite levels were monitored with the aid of in-gel activity assays and high-performance liquid chromatography, respectively. As oxidative phosphorylation was rendered ineffective, the assimilation of citric acid mediated sequentially by citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate phosphate dikinase (PPDK) appeared to play a key role in ATP synthesis via substrate-level phosphorylation (SLP). Enzymes generating the antioxidant, reduced nicotinamide adenine dinucleotide phosphate (NADPH) were enhanced, while metabolic modules mediating the formation of the pro-oxidant, reduced nicotinamide adenine dinucleotide (NADH) were downregulated.
  
  
  CONCLUSIONS
  Pseudomonas fluorescens reengineers its metabolic networks to generate ATP via SLP, a stratagem that allows the microbe to compensate for an ineffective electron transport chain provoked by excess Zn.
  
  
  CONCLUSIONS
  The molecular insights described here are critical in devising strategies to bioremediate Zn-polluted environments.
authors.affiliation: Department Chemistry & Biochemistry, Laurentian University, Sudbury, ON, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Alhasawi
authors.forename: C
authors.initials: C
authors.lastname: Auger
authors.forename: V P
authors.initials: VP
authors.lastname: Appanna
authors.forename: M
authors.initials: M
authors.lastname: Chahma
authors.forename: V D
authors.initials: VD
authors.lastname: Appanna
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000975:Antioxidants / Q000378:metabolism; D002413:Cations, Divalent; D019343:Citric Acid / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000378:metabolism; D011772:Pyruvate, Orthophosphate Dikinase / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015032:Zinc / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D002413:Cations, Divalent; D004785:Environmental Pollutants; D017382:Reactive Oxygen Species; D009243:NAD; D019343:Citric Acid; D009249:NADP; D000255:Adenosine Triphosphate; D011772:Pyruvate, Orthophosphate Dikinase; D010730:Phosphoenolpyruvate Carboxylase; D015032:Zinc
keywords: bioremediation; enzymology; metabolism