Ni2+-uptake in Pseudomonas putida strain S4: a possible role of Mg2+-uptake pump.
Essential metal ion homeostasis is based on regulated uptake of metal ions, both during its scarcity and abundance. Pseudomonas putida strain S4, a multimetal resistant bacterium, was employed to investigate Ni(2+) entry into cells. It was observed that Mg(2+) regulates the entry of Ni(2+) and by this plays a protective role to minimize Ni(2+) toxicity in this strain. This protection was evident in both growth as well as viability. Intracellular accumulation of Ni(2+) varied in accordance with Mg(2+) concentrations in the medium. It was hypothesized that Ni(2+) enters the cell using a broad Mg(2+) pump, i.e. the CorA system, as the CorA inhibitor, i.e. Co(III) Hex, also inhibits Ni 2+ uptake. This led to the inference that Mg(2+)-based protection was basically due to competitive inhibition of Ni(2+) uptake. We also show that Zn(2+) can further regulate the entry of Ni(2+).
Tripathi
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VN
Department of Genetics, University of Delhi, South Campus, New Delhi, India.
Srivastava
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D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003035:Cobalt / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D017136:Ion Transport; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D009532:Nickel / Q000378:metabolism*; D016958:Pseudomonas putida / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism
D027682:Cation Transport Proteins; C030862:cobalt ammonium complex; D003035:Cobalt; D009532:Nickel; D008274:Magnesium; D015032:Zinc