6th International Congress on Applied Biological Sciences, Adana, Turkey, 8 - 09 December 2021, pp.16-17
The yeast Saccharomyces cerevisiae accumulates two types of glucose stores trehalose and glycogen. Glycogen is a multi-branched polysaccharide and trehalose is a non-reducing disaccharide. The levels of these storage carbohydrates change during the incubation of cells to prolonged starvation or stress conditions. The trehalose and glycogen content of cells is regulated by synthesis and degradation enzymes depending on the physiological state of yeast cells. The genes involved in the regulation of reserve carbohydrates are controlled by several signaling pathways. TOR pathway is regulated depending on the quantity and quality of nitrogen in S. cerevisiae. SIR2 encodes an NAD+-dependent deacetylase enzyme involved in chromatin silencing and decreases yeast lifespan. The expression of the yeast SIR2 gene is increased in oxidative stress or intracellular stress conditions The decrease in Sir2 protein activity indirectly causes an increase in intracellular trehalose accumulation. In our research, the reserve carbohydrate accumulation of wild type and Δsir2 yeast cells was determined under nitrogen starvation condition. Ammonium sulfate and proline were used as strong and weak nitrogen sources, respectively. The results showed that the glycogen accumulation of wild-type and Δsir2 yeast cells was greater than the accumulation of trehalose under both normal and starvation conditions. In addition, it was observed that the amount of reserve carbohydrate accumulated by mutant yeast cells in nitrogen starvation was 2-3 times higher than that of wild type yeast cells. These results show that Sir2 protein has a direct or indirect role in the regulation of genes involved in storage carbohydrate metabolism in both stress and normal growth conditions.