The Role of Glucose-6-phosphate Dehydrogenase in the Wine Yeast .

is the predominant yeast species in the majority of wine fermentations, which has only recently become amenable to directed genetic manipulation. The genetics and metabolism of have been poorly studied as compared to other yeasts of biotechnological importance. This work describes the construction and characterization of homozygous deletion mutants in the gene, encoding glucose-6-phosphate dehydrogenase (G6PDH), which provides the entrance into the oxidative part of the pentose phosphate pathway (PPP) and serves as a major source of NADPH for anabolic reactions and oxidative stress response. deletion mutants grow more slowly on glucose medium than wild-type and are hypersensitive both to hydrogen peroxide and potassium bisulfite, indicating that G6PDH activity is required to cope with these stresses. The mutant also requires methionine for growth. Enzyme activity can be restored by the expression of heterologous G6PDH genes from other yeasts and humans under the control of a strong endogenous promoter. These findings provide the basis for a better adaptation of to conditions used in wine fermentations, as well as its use for other biotechnological purposes and as an expression organism for studying G6PDH functions in patients with hemolytic anemia.