Uncovering the interplay between Copper and SO2 tolerance in Saccharomyces cerevisiae
Copper and SO2 tolerance are two well-studied phenotypic traits of Saccharomyces cerevisiae. The genetic bases of these traits are the allelic expansion at the CUP1 locus and reciprocal translocation at the SSU1 locus, respectively. Previous work identified a negative association between SO2 and copper tolerance in S. cerevisiae wine yeasts. To understand the genetic basis of copper sensitivity, we used bulk-segregant QTL analysis and identified genetic variation at the SSU1 locus as a causative factor. This was confirmed through reciprocal hemizygosity analysis in a strain with 20 copies of CUP1. Transcriptional and proteomic analysis revealed that over-expression of SSU1 didn’t suppress CUP1 expression or limit protein production. Instead, it induced sulfur limitation when exposed to copper.Furthermore, we observed that an SSU1 over-expressing strain became more sensitive to moderately elevated copper concentrations in sulfur-limited conditions, indicating a burden on the sulfate assimilation pathway. Over-expression of MET 3/14/16, genes upstream of H2S production in the sulfate assimilation pathway increased the production of SO2 and H2S but did not improve copper sensitivity in an SSU1 over-expressing background. We conclude that copper and SO2 tolerance are conditional traits in S. cerevisiae and provide evidence of the metabolic basis for their mutual exclusivity.
Acknowledgements: For genome sequencing the authors would like to thank the Ramaciotti Center for Genomics which is funded through Bioplatforms Australia Pty Ltd (BPA), a National Collaborative Research Infrastructure Strategy (NCRIS). Proteomic data acquisition was obtained with support of the Adelaide Proteomics Centre at The University of Adelaide, in partnership with the South Australian Health and Medical Research Institute Proteomics Core Facility
1) Onetto CA. et al. (2023). SO2 and copper tolerance exhibit an evolutionary trade-off in Saccharomyces cerevisiae. PLoS Genetics, 19(3), e1010692.
Issue: ICGWS 2023
1The Australian Wine Research Institute, Glen Osmond, South Australia, Australia