Robustness of Saccharomyces Cerevisiae Genome to Antioxidative Stress

ABSTRACT

Recent advances in experimental and computational biology allow addressing of complex questions regarding the evolution of biological adaptation and stress tolerance in yeast cell. Since enzymatic antioxidant defense metabolism in yeast Saccharomyces cerevisiae has been well studied at biochemical and genetic levels, it represents an excellent system for evaluating the relative roles of duplicate genes and alternative metabolic pathways as possible mechanisms for the stability of antioxidant metabolism against null mutations. In this work, the specific role of key antioxidant enzymes for adaptation to oxidative stress in S. cerevisiae was evaluated by screening of a wide selection of gene specific disruption mutants (▵sod1-2, ▵ctt1, cta1, ▵gpx1-3, ▵gtt1-2, ▵ure2, ▵ccp1, ▵tsa1-2, ▵prx1, ▵trr1-2, ▵glr1). It was shown that yeast cells employ a variety of mechanisms to ensure functional robustness against stress conditions. One of the strategies appeared to be gene duplication events that have produced a number of isoenzymes functioning under variable environmental and physiological conditions. However, emergency of alternative pathways represents the most significant mechanism for increasing the robustness of this system.

Keywords:

• antioxidant enzymes
• gene duplication
• isoenzymes
• null mutations
• phenotype
• Saccharomyces cerevisiae