The overexpression of NADPH-producing enzymes counters the oxidative stress evoked by gallium, an iron mimetic.
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.
Bériault
R
R
Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON, P3E 2C6, Canada.
Hamel
R
R
Chenier
D
D
Mailloux
Ryan J
RJ
Joly
H
H
Appanna
V D
VD
D002374:Catalase / Q000378:metabolism; D004789:Enzyme Activation; D004790:Enzyme Induction; D005708:Gallium / Q000378:metabolism*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D007521:Isocitrate Dehydrogenase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D009249:NADP / Q000737:chemistry / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011551:Pseudomonas fluorescens / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D007527:Isoenzymes; D016877:Oxidants; D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; D009249:NADP; D006861:Hydrogen Peroxide; D005708:Gallium; D007501:Iron; D007521:Isocitrate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D002374:Catalase; D013482:Superoxide Dismutase