Examining the Influence of the Sulfur Assimilation Pathway on the Regulation of Yap1 Activity in Saccharomyces cerevisiae

Abstract

Multiple transcription factors confer resistance to the damage caused by reactive oxidants and electrophiles. In S. cerevisiae, these factors include Yap1, a regulator of detoxification genes, and Met4, a regulator of genes involved in sulfur amino acid metabolism. While Met4‐dependent transcriptional activity can be regulated inducibly in yeast, it interacts with other DNA binding proteins, including Cbf1, to enhance expression of genes that influence intracellular levels of cysteine and methionine. Yeast mutants that lack cbf1 and yap1 exhibit decreased viability after treatment with hydrogen peroxide when compared with a wild‐type strain. In addition, activity of a Yap1‐regulated reporter gene is elevated in cbf1 deletion mutants in the presence and absence of hydrogen peroxide and the electrophile, N‐ethylmaleimide, in comparison to wild‐type. However, the effective concentrations for activating the Yap1‐regulated reporter are similar between wild‐type and cbf1‐deficient yeast. Our results suggest that Yap1 activity is potentially elevated in yeast strains lacking other transcription factors that confer resistance to reactive molecules.