On the coupling of intracellular to glycolytic oscillations in yeast.

Abstract

We have investigated the interplay between glycolytic oscillations and intracellular concentration in the yeastSaccharomyces cerevisiae. Intracellular concentration was measured using the fluorophore potassium-binding benzofuranisophthalate(PBFI). We found that is an essential ion for the occurrence of glycolytic oscillations and that intracellular 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 concentration oscillate in a number of yeast strains with mutations in 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 transporter and (ii) a strain with deletion of the late endosomal Nhx1p ( ) transporter. In these two mutant strains intracellular concentration seems to be low, indicating that the two transporters may be involved in transport of into the cytosol. In the strain, Mdm38p oscillations in glycolysis could be restored by addition of the exchange ionophore nigericin. Furthermore, in two nonoscillating mutant strains with a defective V-ATPase and deletion of the Arp1p protein the intracellular is relatively high, suggesting that the V-ATPase is essential for transport of out of the cytosol and that the cytoskeleton may be involved in binding 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 ion is essential for the emergence of oscillations and support the experimental findings using mutant strains.