Effect of Knockout of the PPN1 Polyphosphatase and VTC4 Polyphosphate Synthetase Genes on Saccharomyces cerevisiae Growth on Ethanol and Its Mitochondrial Polyphosphates

Abstract

One of the functions of inorganic polyphosphates (polyP) as compounds with phosphoester bonds is participation in energy metabolism. While yeast mitochondria contain their own pool of polyphosphates, the ways in which these polymers are involved in the functioning of mitochondria in these microorganisms are not well understood. The goal of the present work was to identify the effect of knockout mutations of the VTC4 gene of polyphosphate synthetase and the PPN1 gene of one of the polyphosphatases on the content of polyphosphates and polyphosphatase activity in mitochondria of S. cerevisiae and on the growth characteristics of the mutant strains on ethanol. Knockout of the VTC4 gene was shown to result in a significant decrease in the polyP content in the mitochondria. Knockout of the PPN1 gene led to the disappearance of polyphosphatase activity, but only to a slight increase in the content of mitochondrial polyphosphates during growth on glucose. When grown on ethanol, the polyP content in the mitochondria of this strain was similar to that of the parental strain, and in both strains it was approximately two times less than when grown on glucose. Both mutants were able to grow with ethanol as the carbon source; however, they exhibited a longer lag phase upon transition from glucose consumption to ethanol consumption. It was suggested that mitochondrial polyphosphates may represent the energy reserve of these organelles, which is necessary for the formation of full-fledged mitochondria during transition from glycolysis to oxidative phosphorylation.