Role of conserved serine hydrolases in controlling acetaldehyde toxicity in yeast

Abstract

Acetaldehyde is a toxic by‐product of ethanol consumption that can lead to cancer through to its damaging effect on DNA. Among the genes hypothesized to control acetaldehyde toxicity are a family of conserved serine hydrolases from Saccharomyces cerevisiae, known as FSH1, FSH2, and FSH3. Our goal was to determine the relative role and redundancy of these three serine hydrolases in controlling acetaldehyde toxicity. Their relative redundancy was investigated by combining growth assays with combinatorial knock‐out strains and by measuring the relative substrate specificity of each individually purified hydrolase against esters of similar structures and properties to acetaldehyde. The growth of single deletion strains of FSH1, FSH2, and FSH3 in the presence of various unsaturated aldehydes and ketones did not show substantial differences between the various toxins tested. This suggested that the three homologs likely play compensatory roles. Double and triple knockouts are being constructed to dissect their potentially overlapping roles. For measuring their substrate specificity, FSH1 and FSH2 were expressed heterologously and purified to homogeneity with the purification of FSH3 ongoing. Overall, FSH1 and FSH2 were active against a variety of overlapping esters with higher average catalytic activity for FSH1. Together, we plan to build a map of the complex regulation and overlapping activities of these three serine hydrolase homologues in regulating acetaldehyde toxicity in yeast.