The overexpression of NADPH-producing enzymes counters the oxidative stress evoked by gallium,an iron mimetic |
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| Authors: | R Bériault R Hamel D Chenier Ryan J Mailloux H Joly V D Appanna |
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| Institution: | (1) Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, P3E 2C6, Canada;(2) Department of Engineering Technology, Cambrian College, Sudbury, ON, P3A 3V8, Canada |
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| Abstract: | Gallium (Ga), an iron (Fe) mimetic promoted an oxidative environment and elicited an antioxidative response in Pseudomonas fluorescens. Ga-stressed P. fluorescens was characterized by higher amounts of oxidized lipids and proteins compared to control cells. The oxidative environment
provoked by Ga was nullified by increased synthesis of NADPH. The activity and expression glucose 6-phosphate dehydrogenase
(G6PDH) and isocitrate dehydrogenase-NADP (ICDH) were stimulated in Ga-cultures. The induction of isoenzymes of these dehydrogenases
was also evident in the Ga-stressed cells. Although superoxide dismutase (SOD) activity was significantly enhanced in Ga-stressed
cultures, catalase activity experienced a marked diminution. Fe metabolism appeared to be severely impeded by Ga toxicity.
This is the first demonstration of the oxidative stress evoked by Ga to be neutralized by a reductive environment generated
via the overexpression of NADPH-producing enzymes. |
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| Keywords: | catalase Fe– S clusters gallium toxicity glucose 6-phosphate dehydrogenase isocitrate dehydrogenase isoenzymes NADPH oxidative stress reactive oxygen species superoxide dismutase |
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