The influence of oxidative stress on the respiratory chain activity of Saccharomyces cerevisiae NAD(H) kinase mutant

Abstract:

[Objective] To realize the relationship between respiratory maintenance and anti-oxidative function of Pos5p, the mitochondrial NAD(H) kinase in Saccharomyces cerevisiae. [Methods] The respiratory chain activity and reactive oxygen species (ROS) level of wild-type BY4742, POS5 gene deletion mutant pos5Δ, and pos5Δ containing POS5-YEplac195 plasmid (pos5Δ/POS5-YEp) under exposure to different kinds of oxidative reagents were compared. [Results] At the normal growth condition, pos5Δ exhibited poorer respiratory chain activity than that of BY4742, while pos5Δ/POS5-YEp gave the partial restored activity, consistent with the ROS level of these three strains. Under the oxidative stress of menadione, the respiratory chain activities of BY4742 and pos5Δ decreased, while that of pos5Δ/POS5-YEp increased. Under the oxidative stress of H2O2 and diethyl maleate, nearly all of the activities of BY4742, pos5Δ and pos5Δ/POS5-YEp reduced, with that of pos5Δ most seriously, and that of pos5Δ/POS5-YEp under H2O2 lessened. Thus indicated that the oxidative stress would injury the respiratory chain complex of S. cerevisiae and over-expression of Pos5p could alleviate the injury from menadione and H2O2. [Conclusion] The protecting function of Pos5p on respiratory chain was correlated to its antioxidative defense function.