CAREER: Genetic dissection of stress signaling and defense in yeast

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The goal of this project is to understand how individual organisms with similar genetic makeup can respond differently to environmental stress. The research will focus on studying brewer’s yeast, which is used for industrial fermentation of foods and beverages. Whereas brewer’s yeast can be found in many natural settings, not all yeast cells are well-adapted to tolerate the high-ethanol environments associated with fermentation or brewing. Identifying the gene differences that lead to variation in ethanol tolerance in yeast is expected to have two broad scientific outcomes. The results may permit identification of yeast with better capabilities for agricultural and biotechnology applications. Also, the results could help us understand how genes control stress responses in more complex organisms, such as humans. The project will have educational impacts by providing scientific training opportunities for graduate and undergraduate students in Arkansas, including underrepresented minority groups. In addition, through a partnership with a local fermentation business, the project team will develop two undergraduate laboratory courses on the Science of Brewing, providing hands-on experience in fermentation microbiology and biotechnology. The long-term goal of this research is to understand how variation in gene expression shapes phenotypic differences related to stress defense, using the model eukaryote Saccharomyces cerevisiae. The strategy is to leverage extensive natural variation in the yeast ethanol response in order to investigate acquired stress resistance, where cells pretreated with sub-lethal stress gain the ability to survive an otherwise lethal exposure to stress. To comprehensively identify the suite of genes and processes necessary for high acquired stress resistance in wild yeast strains, a large collection of lines with individual genes knocked out using CRISPR technology will be produced. Then, genotype-to-phenotype relationships will be established by bulk segregant analysis combined with deep sequencing. The CRISPR knock-out lines will also be used to identify key differences in the ethanol-responsive signaling network across diverse yeast strains. The outcomes are expected to provide new insights into: 1) the genetic determinants of acquired stress resistance and cross protection; 2) how these factors differ from those regulating intrinsic stress resistance; 3) whether key regulators responsible for natural variation in stress defense operate through changes in gene expression, protein coding potential, or both; and 4) how stress signaling networks differ across genetically distinct individuals.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.