Open AccessNitrate storage and retrieval in Beta vulgaris : Effects of nitrate and chloride on proton gradients in tonoplast vesicles
Author(s) -
Eduardo Blumwald,
Ronald J. Poole
Publication year - 1985
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.82.11.3683
Subject(s) - vacuole , acridine orange , vesicle , nitrate , chemistry , chloride , electrochemical gradient , proton transport , symporter , atpase , biophysics , biochemistry , membrane , biology , transporter , organic chemistry , cytoplasm , enzyme , apoptosis , gene
The fluorescent probes acridine orange and oxonol-V were used as indicators of pH gradients (ΔpH) and membrane potential differences (ΔΨ), respectively, in membrane vesicles believed to be derived from the tonoplast ofBeta vulgaris L. Low concentrations of nitrate (1-5 mM) caused a partial dissipation of both ΔpH and ΔΨ at vesicle transport sites distinct from the H+ -ATPase. In contrast, chloride dissipated only ΔΨ. A model is proposed in which nitrate and chloride enter the plant cell vacuole in response to a potential generated by the tonoplast H+ -ATPase. Nitrate but not chloride may then be retrieved for metabolic use by the operation of a nitrate/proton symport at the tonoplast.