Yeast Chemogenetic Screening as a Tool to Unravel the Antifungal Mode of Action of Two Selected Selenocyanates

During recent decades, selenium-containing compounds, as with the chemically similar sulfur-containing compounds, have gained considerable interest as cytotoxic and anticancer agents. Selenocyanates represent a well-established class of organic selenium compounds. These agents exhibit a wide range of biological activities. Classically, selenocyanates may cause an increase in the intracellular levels of reactive oxygen species (ROS) and exert cytotoxic activities, thus, acting as pro-oxidants. In this study, chemogenetic profiling was carried out to decipher the resistance mechanisms as central part of the antifungal mode of action against two selected selenocyanates. If a mutant line is less resistant against a compound compared to the wildtype, the gene deleted in that strain seems to be correlated with the resistance. Yeast mutants carrying gene deletions for specific redox-related protein function were employed in the chemogenetic screening. The results of screening reveal the hypersensitivity of mutants carrying deletions for glutathione pool and metabolism. To confirm the results, Arabidopsis mutants deficient in glutathione were subjected to various concentrations of selenocyanates to observe their effects on mutants and the wildtype. A significant dose dependent inhibition in Arabidopsis mutants compared to the wildtype confirmed the findings of the chemogenetic screening. The data suggest that the two representatives of organoselenium compounds cause oxidative stress in yeast cells and glutathione participates towards the development of resistance against the chemicals.