Role of Saccharomyces cerevisiae Trk1 in stabilization of intracellular potassium content upon changes in external potassium levels

https://doi.org/10.1016/j.bbamem.2013.08.022Get rights and content
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Highlights

  • A new function of ScTrk1 in stabilization of intracellular potassium is proposed.

  • This function is linked to the capacity to transport potassium.

  • Wild type and mutants have different adaptive processes to changes in external K+.

  • A connection Pma1/Trk in the stabilization of intracellular potassium is proposed.

Abstract

Saccharomyces cerevisiae cells are able to grow at very different potassium concentrations adapting its intracellular cation levels to changes in the external milieu. Potassium homeostasis in wild type cells resuspended in media with low potassium is an example of non-perfect adaptation since the same intracellular concentration is not approached irrespective of the extracellular levels of the cation. By using yeasts lacking the Trk1,2 system or expressing different versions of the mutated main plasma membrane potassium transporter (Trk1), we show that Trk1 is not essential for adaptation to potassium changes but the dynamics of potassium loss is very different in the wild type and in trk1,2 mutant or in yeasts expressing Trk1 versions with highly impaired transport characteristics. We also show that the pattern here described can be also fulfilled by heterologous expression of NcHAK1, a potassium transporter not belonging to the TRK family. Hyperpolarization and cationic drugs sensitivity in mutants with defective transport capacity provide additional support to the hypothesis of connections between the activity of the Trk system and the plasma membrane H+ ATPase (Pma1) in the adaptive process.

Keywords

Saccharomyces cerevisiae
Trk transporter
Intracellular potassium
Non-perfect adaptation

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These authors contributed equally to the work.