On the coupling of intracellular K⁺ to glycolytic oscillations in yeast

We have investigated the interplay between glycolytic oscillations and intracellular (Formula presented.) concentration in the yeast Saccharomyces cerevisiae. Intracellular (Formula presented.) concentration was measured using the fluorophore potassium-binding benzofuranisophthalate (PBFI). We found that (Formula presented.) is an essential ion for the occurrence of glycolytic oscillations and that intracellular (Formula presented.) concentration oscillates synchronously with other variables such as nicotinamide adenine dinucleotide hydride (NADH), intracellular adenosine triphosphate (ATP), and mitochondrial membrane potential. We also investigated if glycolysis and intracellular (Formula presented.) concentration oscillate in a number of yeast strains with mutations in (Formula presented.) transporters in the plasma membrane, mitochondrial membrane and in the vacuolar membrane. Most of these strains are still capable of showing glycolytic oscillations, but two strains are not: (i) a strain with a deletion in the mitochondrial Mdm38p (Formula presented.) transporter and (ii) a strain with deletion of the late endosomal Nhx1p (Formula presented.) ((Formula presented.)) transporter. In these two mutant strains intracellular (Formula presented.) concentration seems to be low, indicating that the two transporters may be involved in transport of (Formula presented.) into the cytosol. In the strain, Mdm38p (Formula presented.) oscillations in glycolysis could be restored by addition of the (Formula presented.) exchange ionophore nigericin. Furthermore, in two nonoscillating mutant strains with a defective V-ATPase and deletion of the Arp1p protein the intracellular (Formula presented.) is relatively high, suggesting that the V-ATPase is essential for transport of (Formula presented.) out of the cytosol and that the cytoskeleton may be involved in binding (Formula presented.) to reduce the concentration of free ion in the cytosol. Analyses of the time series of oscillations of NADH, ATP, mitochondrial membrane potential, and potassium concentration using data-driven modeling corroborate the conjecture that (Formula presented.) ion is essential for the emergence of oscillations and support the experimental findings using mutant strains.