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A fungal nitrate carrier with two transport mechanisms.

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A fungal nitrate carrier with two transport mechanisms. / Zhou, Jing-Jiang; Trueman, Laurence J.; Boorer, Kathryn J.; Theodoulou, Frederica L.; Forde, Brian G.; Miller, Anthony J.

In: Journal of Biological Chemistry, Vol. 275, No. 51, 22.12.2000, p. 39894-39899.

Research output: Contribution to journalJournal articlepeer-review

Harvard

Zhou, J-J, Trueman, LJ, Boorer, KJ, Theodoulou, FL, Forde, BG & Miller, AJ 2000, 'A fungal nitrate carrier with two transport mechanisms.', Journal of Biological Chemistry, vol. 275, no. 51, pp. 39894-39899. https://doi.org/10.1074/jbc.M004610200

APA

Zhou, J-J., Trueman, L. J., Boorer, K. J., Theodoulou, F. L., Forde, B. G., & Miller, A. J. (2000). A fungal nitrate carrier with two transport mechanisms. Journal of Biological Chemistry, 275(51), 39894-39899. https://doi.org/10.1074/jbc.M004610200

Vancouver

Zhou J-J, Trueman LJ, Boorer KJ, Theodoulou FL, Forde BG, Miller AJ. A fungal nitrate carrier with two transport mechanisms. Journal of Biological Chemistry. 2000 Dec 22;275(51):39894-39899. https://doi.org/10.1074/jbc.M004610200

Author

Zhou, Jing-Jiang ; Trueman, Laurence J. ; Boorer, Kathryn J. ; Theodoulou, Frederica L. ; Forde, Brian G. ; Miller, Anthony J. / A fungal nitrate carrier with two transport mechanisms. In: Journal of Biological Chemistry. 2000 ; Vol. 275, No. 51. pp. 39894-39899.

Bibtex

@article{305ccb7820434a55a34090496a65a992,
title = "A fungal nitrate carrier with two transport mechanisms.",
abstract = "We have expressed the CRNA high affinity nitrate transporter from Emericella (Aspergillus) nidulans in Xenopus oocytes and used electrophysiology to study its properties. This method was used because there are no convenient radiolabeled substrates for the transporter. Oocytes injected with crnA mRNA showed nitrate-, nitrite-, and chlorite-dependent currents. Although the gene was originally identified by chlorate selection there was no evidence for transport of this anion. The gene selection is explained by the high affinity of the transporter for chlorite, and the fact that this ion contaminates solutions of chlorate. The pH-dependence of the anion-elicited currents was consistent with H+-coupled mechanism of transport. At any given voltage, currents showed hyperbolic kinetics with respect to extracellular H+, and these data could be fitted with a Michaelis-Menten relationship. But this equation did not adequately describe transport of the anion substrates. At higher concentrations of the anion substrates and more negative membrane voltages, the currents were decreased, but this effect was independent of changes in external pH. These more complicated kinetics could be fit by an equation containing two Michaelis-Menten terms. The substrate inhibition of the currents could be explained by a transport reaction cycle that included two routes for the transfer of nitrate across the membrane, one on the empty carrier and the other proton coupled. The model predicts that the substrate inhibition of transporter current depends on the cytosolic nitrate concentration. This is the first time a high affinity nitrate transport activity has been characterized in a heterologous system and the measurements show how the properties of the CRNA transporter are modified by changes in the membrane potential, external pH, and nitrate concentration. The physiological significance of these observations is discussed.",
author = "Jing-Jiang Zhou and Trueman, {Laurence J.} and Boorer, {Kathryn J.} and Theodoulou, {Frederica L.} and Forde, {Brian G.} and Miller, {Anthony J.}",
year = "2000",
month = dec,
day = "22",
doi = "10.1074/jbc.M004610200",
language = "English",
volume = "275",
pages = "39894--39899",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "51",

}

RIS

TY - JOUR

T1 - A fungal nitrate carrier with two transport mechanisms.

AU - Zhou, Jing-Jiang

AU - Trueman, Laurence J.

AU - Boorer, Kathryn J.

AU - Theodoulou, Frederica L.

AU - Forde, Brian G.

AU - Miller, Anthony J.

PY - 2000/12/22

Y1 - 2000/12/22

N2 - We have expressed the CRNA high affinity nitrate transporter from Emericella (Aspergillus) nidulans in Xenopus oocytes and used electrophysiology to study its properties. This method was used because there are no convenient radiolabeled substrates for the transporter. Oocytes injected with crnA mRNA showed nitrate-, nitrite-, and chlorite-dependent currents. Although the gene was originally identified by chlorate selection there was no evidence for transport of this anion. The gene selection is explained by the high affinity of the transporter for chlorite, and the fact that this ion contaminates solutions of chlorate. The pH-dependence of the anion-elicited currents was consistent with H+-coupled mechanism of transport. At any given voltage, currents showed hyperbolic kinetics with respect to extracellular H+, and these data could be fitted with a Michaelis-Menten relationship. But this equation did not adequately describe transport of the anion substrates. At higher concentrations of the anion substrates and more negative membrane voltages, the currents were decreased, but this effect was independent of changes in external pH. These more complicated kinetics could be fit by an equation containing two Michaelis-Menten terms. The substrate inhibition of the currents could be explained by a transport reaction cycle that included two routes for the transfer of nitrate across the membrane, one on the empty carrier and the other proton coupled. The model predicts that the substrate inhibition of transporter current depends on the cytosolic nitrate concentration. This is the first time a high affinity nitrate transport activity has been characterized in a heterologous system and the measurements show how the properties of the CRNA transporter are modified by changes in the membrane potential, external pH, and nitrate concentration. The physiological significance of these observations is discussed.

AB - We have expressed the CRNA high affinity nitrate transporter from Emericella (Aspergillus) nidulans in Xenopus oocytes and used electrophysiology to study its properties. This method was used because there are no convenient radiolabeled substrates for the transporter. Oocytes injected with crnA mRNA showed nitrate-, nitrite-, and chlorite-dependent currents. Although the gene was originally identified by chlorate selection there was no evidence for transport of this anion. The gene selection is explained by the high affinity of the transporter for chlorite, and the fact that this ion contaminates solutions of chlorate. The pH-dependence of the anion-elicited currents was consistent with H+-coupled mechanism of transport. At any given voltage, currents showed hyperbolic kinetics with respect to extracellular H+, and these data could be fitted with a Michaelis-Menten relationship. But this equation did not adequately describe transport of the anion substrates. At higher concentrations of the anion substrates and more negative membrane voltages, the currents were decreased, but this effect was independent of changes in external pH. These more complicated kinetics could be fit by an equation containing two Michaelis-Menten terms. The substrate inhibition of the currents could be explained by a transport reaction cycle that included two routes for the transfer of nitrate across the membrane, one on the empty carrier and the other proton coupled. The model predicts that the substrate inhibition of transporter current depends on the cytosolic nitrate concentration. This is the first time a high affinity nitrate transport activity has been characterized in a heterologous system and the measurements show how the properties of the CRNA transporter are modified by changes in the membrane potential, external pH, and nitrate concentration. The physiological significance of these observations is discussed.

U2 - 10.1074/jbc.M004610200

DO - 10.1074/jbc.M004610200

M3 - Journal article

VL - 275

SP - 39894

EP - 39899

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 51

ER -