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J Biol Chem. 2017 Jan 13;292(2):563-574. doi: 10.1074/jbc.M116.746982. Epub 2016 Nov 28.

Reciprocal Regulation of Target of Rapamycin Complex 1 and Potassium Accumulation.

Author information

1
From the Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Avd. de los Naranjos s/n, Valencia, Spain 46022 and.
2
the Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), Swiss National Centre for Competence in Research in Chemical Biology, University of Geneva, 1211 Geneva, Switzerland.
3
From the Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Avd. de los Naranjos s/n, Valencia, Spain 46022 and lynne@ibmcp.upv.es.

Abstract

The proper maintenance of potassium homeostasis is crucial for cell viability. Among the major determinants of potassium uptake in the model organism Saccharomyces cerevisiae are the Trk1 high affinity potassium transporter and the functionally redundant Hal4 (Sat4) and Hal5 protein kinases. These kinases are required for the plasma membrane accumulation of not only Trk1 but also several nutrient permeases. Here, we show that overexpression of the target of rapamycin complex 1 (TORC1) effector NPR1 improves hal4 hal5 growth defects by stabilizing nutrient permeases at the plasma membrane. We subsequently found that internal potassium levels and TORC1 activity are linked. Specifically, growth under limiting potassium alters the activities of Npr1 and another TORC1 effector kinase, Sch9; hal4 hal5 and trk1 trk2 mutants display hypersensitivity to rapamycin, and reciprocally, TORC1 inhibition reduces potassium accumulation. Our results demonstrate that in addition to carbon and nitrogen, TORC1 also responds to and regulates potassium fluxes.

KEYWORDS:

endocytosis; intracellular trafficking; potassium transport; target of rapamycin (TOR); yeast

PMID:
27895122
PMCID:
PMC5241732
DOI:
10.1074/jbc.M116.746982
[Indexed for MEDLINE]
Free PMC Article

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