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  • A genomewide screen for tolerance to cationic drugs reveals genes important for potassium homeostasis in Saccharomyces cerevisiae.

A genomewide screen for tolerance to cationic drugs reveals genes important for potassium homeostasis in Saccharomyces cerevisiae.

Eukaryotic cell (2011-07-05)
Lina Barreto, David Canadell, Silvia Petrezsélyová, Clara Navarrete, Lydie Maresová, Jorge Peréz-Valle, Rito Herrera, Iván Olier, Jesús Giraldo, Hana Sychrová, Lynne Yenush, José Ramos, Joaquín Ariño
ABSTRACT

Potassium homeostasis is crucial for living cells. In the yeast Saccharomyces cerevisiae, the uptake of potassium is driven by the electrochemical gradient generated by the Pma1 H(+)-ATPase, and this process represents a major consumer of the gradient. We considered that any mutation resulting in an alteration of the electrochemical gradient could give rise to anomalous sensitivity to any cationic drug independently of its toxicity mechanism. Here, we describe a genomewide screen for mutants that present altered tolerance to hygromycin B, spermine, and tetramethylammonium. Two hundred twenty-six mutant strains displayed altered tolerance to all three drugs (202 hypersensitive and 24 hypertolerant), and more than 50% presented a strong or moderate growth defect at a limiting potassium concentration (1 mM). Functional groups such as protein kinases and phosphatases, intracellular trafficking, transcription, or cell cycle and DNA processing were enriched. Essentially, our screen has identified a substantial number of genes that were not previously described to play a direct or indirect role in potassium homeostasis. A subset of 27 representative mutants were selected and subjected to diverse biochemical tests that, in some cases, allowed us to postulate the basis for the observed phenotypes.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Tetramethylammonium hydroxide solution, 10 wt. % in H2O
Sigma-Aldrich
Tetramethylammonium hydroxide solution, 25 wt. % in H2O
Sigma-Aldrich
Tetramethylammonium chloride, reagent grade, ≥98%
Sigma-Aldrich
Tetramethylammonium hydroxide solution, ACS reagent
Supelco
Tetramethylammonium sulfate, suitable for ion pair chromatography, LiChropur, ≥99.0% (T)
Sigma-Aldrich
Tetramethylammonium chloride, BioUltra, for molecular biology, ≥99.0% (AT)
Sigma-Aldrich
Tetramethylammonium hydroxide solution, 25 wt. % in methanol
Sigma-Aldrich
Tetramethylammonium fluoride, 97%
Supelco
Tetramethylammonium chloride, suitable for ion pair chromatography, LiChropur, ≥99.0% (AT)
Sigma-Aldrich
Tetramethylammonium chloride solution, for molecular biology
Sigma-Aldrich
Tetramethylammonium hydroxide pentahydrate, ≥97%
Sigma-Aldrich
Tetramethylammonium hydroxide pentahydrate, ≥95.0% (T)
Supelco
Tetramethylammonium bromide, suitable for ion pair chromatography, LiChropur, ≥99.0% (AT)
Sigma-Aldrich
Tetramethylammonium iodide, 99%
Sigma-Aldrich
Tetramethylammonium bromide, 98%
Sigma-Aldrich
Tetramethylammonium bromide, ACS reagent, ≥98.0%