Saccharomyces cerevisiae Genome sequencing. Saccharomyces cerevisiae

Here, we perform a screen for spontaneous mutations that improve the tolerance of haploid Saccharomyces cerevisiae to hydrogen peroxide. Chromosome IV duplication is the most frequent mutational event, as well as the only change in chromosomal copy number, seen in the screen. Genetic mapping and gene expression analysis reveal that this chromosomal duplication’s effect is mostly mediated by a single stress-inducible cytoplasmic thioredoxin peroxidase that shows altered transcriptional dynamics in response to hydrogen peroxide exposure in an aneuploid mutant relative to its euploid progenitor.