LB 17-181 - Pleiotropic effects of adaptation to metals in yeast

Thursday, August 18, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

Penelope C. Kahn

PhD Student
University of British Columbia
Vancouver, British Columbia, Canada

Coauthor(s)

AB

Anna Bazzicalupo

Post-doc
University of British Columbia
Vancouver, British Columbia, Canada
Penelope C. Kahn

PhD Student
University of British Columbia
Vancouver, British Columbia, Canada
SO

Sarah P. Otto

Principal Invesitgator
University of British Columbia
Vancouver, British Columbia, Canada

Background/Question/Methods:

Industrialization over the past century has led to a massive increase in the use and release of heavy metals into the environment, several of which (e.g., manganese, zinc) act as micronutrients in the eukaryotic cell but are toxic at high concentrations. In sites affected by complex contamination, organisms must tolerate the effects of multiple metals in order to survive, yet we do not know how mutations that are adaptive for one metal affect tolerance to others. In order to predict the magnitude and direction of pleiotropy in this system, we performed a correlation analysis of knockout and overexpression mutations reported to confer metal resistance in the Saccharomyces genome database (SGD). We tested the predictive power of this analysis using short-term evolution experiments in which we generated and isolated yeast lines with large-effect mutations allowing yeast to survive in otherwise lethal levels of each of seven different metals. We then perform reciprocal transplant experiments to measure the maximum growth rates of the evolved lines for one metal in the presence of each of the other metals to test predictions from SGD.

Results/Conclusions:

Our results from metal adapted lines confirm that cross-tolerance to other metals is greater for those with a higher proportion of shared genes reported to affect metal resistance in SGD, with some notable exceptions. For example, lines adapted to copper have higher fitness in manganese and cadmium, consistent with the SGD predictions, but lines adapted to manganese do not have higher fitness in cadmium, as predicted by SGD. Furthermore, a general linear model accounting for evolution environment, test environment, and the interaction of these two environments showed significantly higher cross-tolerance than would be expected by chance for 88% of the metal combinations. This work aims to predict which combinations of environmental stressors will be easy or challenging for microbial adaptation, leveraging the power of yeast as a model system.