Redox perturbations in yeast cells lacking glutathione reductase

Cellular redox homeostasis has a major effect on cell functions and its maintenance is supported by glutathione and protein thiols which serve as redox buffers in cells. The regulation of the glutathione biosynthetic pathway is a focus of a lot of scientific research. However, still little is known about how complex cellular networks in-fluence glutathione homeostasis. In this work was used an experimental system based on an S. cerevisiae yeast mutant with a lack of the glutathione reductase enzyme and allyl alcohol as a precursor of acrolein inside the cell to determine the cellular processes influencing glutathione homeostasis. The absence of Glr1p slows down the growth rate of the cell population, especially in the presence of allyl alcohol, but does not lead to complete inhibition of the cell's reproductive capacity. It also amends the GSH/GSSG ratio and the share of NADPH and NADP+ in the total NADP(H) pool. The obtained results show that potential pathways involved in the mainte-nance of redox homeostasis are based from one side on de novo synthesis of GSH as indicated by increased ac-tivity of gamma-GCS and increased expression of GSH1 gene in the Delta glr1 mutant, from the other hand, on increased the level of NADPH. This is because the lower ratio of GSH/GSSG can be counterbalanced with the NADPH/NADP+ alternative system. The higher level of NADPH can be used by the thioredoxin system and other enzymes requiring NADPH to reduce cytosolic GSSG and maintain glutathione redox potential.

Automated summary

Cellular redox homeostasis is regulated by glutathione and protein thiols as redox buffers. However, the mechanisms of cellular network influencing glutathione homeostasis still remain unclear. In this study, an experimental system using a S. cerevisiae yeast mutant lacking glutathione reductase enzyme was employed to investigate cellular processes affecting glutathione homeostasis. The absence of Glr1p slowed down cell growth rate, especially in the presence of allyl alcohol, but did not completely inhibit cell reproductive capacity. It also affected the GSH/GSSG ratio and the balance of NADPH and NADP+ in the total NADP(H) pool. The results suggest that de novo synthesis of GSH and increased NADPH level are potential pathways involved in maintaining redox homeostasis.