The flip side of the Arabidopsis type I proton-pumping pyrophosphatase (AVP1): Using a transmembrane H gradient to synthesize pyrophosphate

Joachim Scholz-Starke, Cecilia Primo, Jian Yang, Raju Kandel, Roberto A. Gaxiola, Kendal D. Hirschi

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Energy partitioning and plant growth are mediated in part by a type I H-pumping pyrophosphatase (H-PPase). A canonical role for this transporter has been demonstrated at the tonoplast where it serves a job-sharing role with V-ATPase in vacuolar acidification. Here, we investigated whether the plant H-PPase from Arabidopsis also functions in “reverse mode” to synthesize PPi using the transmembrane H gradient. Using patch-clamp recordings on Arabidopsis vacuoles, we observed inward currents upon Pi application on the cytosolic side. These currents were strongly reduced in vacuoles from two independent H-PPase mutant lines (vhp1-1 and fugu5-1) lacking the classical PPi-induced outward currents related to H pumping, whereas they were significantly larger in vacuoles with engineered heightened expression of the H-PPase. Current amplitudes related to reverse-mode H transport depended on the membrane potential, cytosolic Pi concentration, and magnitude of the pH gradient across the tonoplast. Of note, experiments on vacuolar membrane- enriched vesicles isolated from yeast expressing the Arabidopsis H-PPase (AVP1) demonstrated Pi-dependent PPi synthase activity in the presence of a pH gradient. Our work establishes that a plant H-PPase can operate as a PPi synthase beyond its canonical role in vacuolar acidification and cytosolic PPi scavenging. We propose that the PPi synthase activity of H-PPase contributes to a cascade of events that energize plant growth.

Original languageEnglish (US)
Pages (from-to)1290-1299
Number of pages10
JournalJournal of Biological Chemistry
Volume294
Issue number4
DOIs
StatePublished - Jan 25 2019

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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