Lack of main K+ uptake systems in Saccharomyces cerevisiae cells affects yeast performance in both potassium-sufficient and potassium-limiting conditions

Abstract

A new YNB medium containing very low concentrations of alkali metal cations has been developed to carry out experiments to study potassium homoeostasis. Physiological characterization of Saccharomyces cerevisiae BY4741 strain and the corresponding mutant lacking the main potassium uptake systems (trk1 trk2) under potassium nonlimiting and limiting concentrations was performed, and novel important differences between both strains were found. At nonlimiting concentrations of KCl, the two strains had a comparable cell size and potassium content. Nevertheless, mutants were hyperpolarized, had lower pH and extruded fewer protons compared with the BY4741 strain. Upon transfer to K(+)-limiting conditions, cells of both strains became hyperpolarized and their cell volume and K(+) content diminished; however, the decrease was more relevant in BY4741. In low potassium, trk1 trk2 cells were not able to accomplish the cell cycle to the same extent as in BY4741. Moreover, K(+) limitation triggered a high-affinity K(+)/Rb(+) uptake process only in BY4741, with the highest affinity being reached as soon as 30 min after transfer to potassium-limiting conditions. By establishing basic cellular parameters under standard growth conditions, this work aims to establish a basis for the investigation of potassium homoeostasis at the system level.

Hal4 and Hal5 Protein Kinases Are Required for General Control of Carbon and Nitrogen Uptake and Metabolism

“…EUKARYOT. CELL 1A) and are in agreement with those recently reported for the trk1 trk2 strain (22). These observations suggest that the lower intracellular potassium concentration of the hal4 hal5 mutant is not the only cause of the cytosolic acidification of this mutant.…”

A Genomewide Screen for Tolerance to Cationic Drugs Reveals Genes Important for Potassium Homeostasis in Saccharomyces cerevisiae

“…Unless stated otherwise, yeast cells were grown at 28°C in Translucent medium (catalog number CYN7505; Formedium, United Kingdom), prepared as described previously (33) and containing in each case the specified concentration of KCl. Translucent medium is a yeast nitrogen base (YNB)-based medium that has been reformulated to contain negligible amounts of potassium (usually Ͻ15 M).…”

Nitrate-dependent control of shoot K homeostasis by NPF7.3/NRT1.5 and SKOR in Arabidopsis

“…Accordingly, the deletion of both TRK genes in BYT12 cells results in a higher sensitivity to toxic cations, even under nonlimiting K + concentrations in the medium (Navarrete et al, 2010), because of a hyperpolarization of the plasma membrane. To investigate whether Relative transcript levels of six regulated genes in roots of hydroponically grown plants were measured by qPCR and normalized to UBQ10 (means 6 SD; n = 4).…”