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The signaling lipid phosphatidylinositol-3,5-bisphosphate targets plant CLC-a anion/H+ exchange activity.


ABSTRACT: Phosphatidylinositol-3,5-bisphosphate (PI(3,5)P2) is a low-abundance signaling lipid associated with endo-lysosomal and vacuolar membranes in eukaryotic cells. Recent studies on Arabidopsis indicated a critical role of PI(3,5)P2 in vacuolar acidification and morphology during ABA-induced stomatal closure, but the molecular targets in plant cells remained unknown. By using patch-clamp recordings on Arabidopsis vacuoles, we show here that PI(3,5)P2 does not affect the activity of vacuolar H+-pyrophosphatase or vacuolar H+-ATPase. Instead, PI(3,5)P2 at low nanomolar concentrations inhibited an inwardly rectifying conductance, which appeared upon vacuolar acidification elicited by prolonged H+ pumping activity. We provide evidence that this novel conductance is mediated by chloride channel a (CLC-a), a member of the anion/H+ exchanger family formerly implicated in stomatal movements in Arabidopsis H+-dependent currents were absent in clc-a knock-out vacuoles, and canonical CLC-a-dependent nitrate/H+ antiport was inhibited by low concentrations of PI(3,5)P2 Finally, using the pH indicator probe BCECF, we show that CLC-a inhibition contributes to vacuolar acidification. These data provide a mechanistic explanation for the essential role of PI(3,5)P2 and advance our knowledge about the regulation of vacuolar ion transport.

SUBMITTER: Carpaneto A 

PROVIDER: S-EPMC5494527 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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The signaling lipid phosphatidylinositol-3,5-bisphosphate targets plant CLC-a anion/H<sup>+</sup> exchange activity.

Carpaneto Armando A   Boccaccio Anna A   Lagostena Laura L   Di Zanni Eleonora E   Scholz-Starke Joachim J  

EMBO reports 20170523 7


Phosphatidylinositol-3,5-bisphosphate (PI(3,5)P<sub>2</sub>) is a low-abundance signaling lipid associated with endo-lysosomal and vacuolar membranes in eukaryotic cells. Recent studies on <i>Arabidopsis</i> indicated a critical role of PI(3,5)P<sub>2</sub> in vacuolar acidification and morphology during ABA-induced stomatal closure, but the molecular targets in plant cells remained unknown. By using patch-clamp recordings on <i>Arabidopsis</i> vacuoles, we show here that PI(3,5)P<sub>2</sub> do  ...[more]

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