Vacuolar chloride regulation of an anion-selective tonoplast channel

P. J. Plant, Angela C Gelli, E. Blumwald

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

Fluctuations in intravacuolar chloride concentrations affected the tonoplast inward (anion flux into the vacuole) currents of sugar beets (Beta vulgaris). Rising vacuolar chloride concentrations induced increases in the levels of nitrate, acetate and phosphate inward currents. These currents, evoked at physiological vacuolar potentials, showed a linear relationship with the concentration of vacuolar chloride between 6 and 100 m m. Single channel currents revealed that rises in vacuolar chloride increased the frequency and probability of channel openings at a given tonoplast potential by reducing the mean closed time of the anion channel. In addition, there was an increase in the gating charge for the channel and a decrease in the free-energy favoring the transition of the channel from the closed to the open state. Vacuolar chloride had a very different effect on malate currents. Increasing chloride concentrations resulted in decreased frequency and open probability of the channel openings, a decrease in the gating charge and an increase in the mean closed time of the channel. Our results support the role for vacuolar chloride concentrations regulating the influx of anions into the vacuole, in addition to osmoregulation. The activation of channel activity by chloride will provide a pathway for the storage of nutrients, such as nitrate and phosphate into the vacuole, while the reduction of the malate currents will allow the use of malate for mitochondrial oxidation and cytoplasmic pH control.

Original languageEnglish (US)
Pages (from-to)1-12
Number of pages12
JournalThe Journal of Membrane Biology
Volume140
Issue number1
DOIs
StatePublished - May 1994
Externally publishedYes

Keywords

  • Anion channels
  • Beet vacuoles
  • Chloride regulation
  • Inward currents
  • Patch clamp
  • Tonoplast

ASJC Scopus subject areas

  • Physiology
  • Cell Biology
  • Biophysics

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