Engineered Trx2p industrial yeast strain protects glycolysis and fermentation proteins from oxidative carbonylation during biomass propagation

In this work we have found several proteins specifically protected by yeast Thioredoxin 2 (Trx2p). Bidimensional electrophoresis and carbonylated protein identification from TRX-deficient and TRX-overexpressing cells revealed that glycolysis and fermentation-related proteins are specific targets of Trx2p protection. Indeed, the TRX2 overexpressing strain presented increased activity of the central carbon metabolism enzymes. Interestingly, Trx2p specifically preserved alcohol dehydrogenase I (Adh1p) from carbonylation, decreased oligomer aggregates and increased its enzymatic activity.The identified proteins suggest that the fermentative capacity detriment observed under industrial conditions in T73 wine commercial strain results from the oxidative carbonylation of specific glycolytic and fermentation enzymes. Indeed, increased thioredoxin levels enhance the performance of key fermentation enzymes such as Adh1p, which consequently increases fermentative capacity.In the industrial yeast biomass propagation process, oxidative stress plays an important role by decreasing biomass yield and affecting fermentative properties of the produced biomass [1,2]. Studying oxidative stress during the biomass propagation process is essential to obtain stress-resistant yeasts that are able to complete the industrial process with no detriment of their fermentative and growth properties. Under industrial conditions, many cellular components are negatively affected since lipid peroxidation increases, while total glutathione and catalase activity decrease [3]. However, TRX2 gene overexpression improves Saccharomyces cerevisiae oxidative stress response by diminishing the damage caused by ROS (reactive oxygen species) accumulation [3]. Trx2p is part of the cytosolic TRX system (thioredoxin1, thioredoxin 2, TRX reductase and NADPH) which reduces oxidized cysteine groups on proteins [4]. Thioredoxins act as reducing agents of the oxidized form of TRX peroxidase (TSA1), then favoring the act