NarK is a nitrite-extrusion system involved in anaerobic nitrate respiration by Escherichia coli.
Escherichia coli can use nitrate as a terminal electron acceptor for anaerobic respiration. A polytopic membrane protein, termed NarK, has been implicated in nitrate uptake and nitrite excretion and is thought to function as a nitrate/nitrite antiporter. The longest-lived radioactive isotope of nitrogen, 13N-nitrate (half-life = 9.96 min) and the nitrite-sensitive fluorophore N-(ethoxycarbonylmethyl)-6-methoxyquinolinium bromide have now been used to define the function of NarK. At low concentrations of nitrate, NarK mediates the electrogenic excretion of nitrite rather than nitrate/nitrite exchange. This process prevents intracellular accumulation of toxic levels of nitrite and allows further detoxification in the periplasm through the action of nitrite reductase.
Rowe
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Department of Biology, University of Dayton, Ohio 45469-2320.
Ubbink-Kok
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Molenaar
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Konings
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Driessen
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D000693:Anaerobiosis; D027321:Anion Transport Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D000091285:Nitrate Transporters; D009566:Nitrates / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D011510:Proteolipids / Q000378:metabolism
D027321:Anion Transport Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D000091285:Nitrate Transporters; D009566:Nitrates; D009573:Nitrites; D011510:Proteolipids; C020485:proteoliposomes