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Plant Cell. 2015 Dec;27(12):3383-96. doi: 10.1105/tpc.15.00733. Epub 2015 Nov 20.

Job Sharing in the Endomembrane System: Vacuolar Acidification Requires the Combined Activity of V-ATPase and V-PPase.

Author information

1
Department of Plant Developmental Biology, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany.
2
Department of Stem Cell Biology, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany.
3
Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742.
4
Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907.
5
Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland 20742 Environmental Science and Technology, University of Maryland, College Park, Maryland 20742.
6
Department of Plant Developmental Biology, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany karin.schumacher@cos.uni-heidelberg.de.

Abstract

The presence of a large central vacuole is one of the hallmarks of a prototypical plant cell, and the multiple functions of this compartment require massive fluxes of molecules across its limiting membrane, the tonoplast. Transport is assumed to be energized by the membrane potential and the proton gradient established by the combined activity of two proton pumps, the vacuolar H(+)-pyrophosphatase (V-PPase) and the vacuolar H(+)-ATPase (V-ATPase). Exactly how labor is divided between these two enzymes has remained elusive. Here, we provide evidence using gain- and loss-of-function approaches that lack of the V-ATPase cannot be compensated for by increased V-PPase activity. Moreover, we show that increased V-ATPase activity during cold acclimation requires the presence of the V-PPase. Most importantly, we demonstrate that a mutant lacking both of these proton pumps is conditionally viable and retains significant vacuolar acidification, pointing to a so far undetected contribution of the trans-Golgi network/early endosome-localized V-ATPase to vacuolar pH.

PMID:
26589552
PMCID:
PMC4707456
DOI:
10.1105/tpc.15.00733
[Indexed for MEDLINE]
Free PMC Article

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