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Zinc toxicity and ATP production in Pseudomonas fluorescens
Author(s) -
Alhasawi A.,
Auger C.,
Appanna V.P.,
Chahma M.,
Appanna V.D.
Publication year - 2014
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12497
Subject(s) - pseudomonas fluorescens , biochemistry , nicotinamide adenine dinucleotide phosphate , nicotinamide adenine dinucleotide , phosphoenolpyruvate carboxylase , enzyme , pseudomonas , metabolite , chemistry , phosphate , metabolic pathway , biology , nad+ kinase , bacteria , oxidase test , genetics
Aims To identify the molecular networks in P seudomonas fluorescens that convey resistance to toxic concentrations of Z n, a common pollutant and hazard to biological systems. Methods and Results Pseudomonas fluorescens strain ATCC 13525 was cultured in growth medium with millimolar concentrations of Z n. 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 P seudomonas 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 Z n. Significance and Impact of the Study The molecular insights described here are critical in devising strategies to bioremediate Z n‐polluted environments.