GEE Friday Seminar - Dr Sonal, Research Fellow, CLOE

Abstract: Cells often interact via secreted metabolites. If the metabolites are gaseous, they could mediate interactions between seemingly unconnected cell populations. Hydrogen sulfide is one such volatile metabolite that nearly all cell types generate by degrading sulfur-containing amino acids. The gas can cross membranes unassisted and lead to varied effects: High doses of sulfide can poison eukaryotic cells, while lower doses can promote longevity in yeast, antibiotic resistance in bacteria and epithelial integrity in the human gut. Here, I will discuss how sulfide can mediate cell-cell interactions in Saccharomyces cerevisiae by triggering a hitherto unknown pathway of sulfur assimilation. The current understanding of yeast sulfur metabolism asserts that the enzyme Met17 is necessary for yeast to assimilate inorganic sulfate. However, we found that Met17-deficient yeast can in fact grow on sulfate, albeit only at high initial cell densities. I will show that this density-dependent growth is driven by a sulfide-sensitive pathway, and discuss how we seek to understand the mechanisms of this pathway via quantitative modeling and genetic tools. We hope that this work will not only reveal novel aspects of yeast sulfur metabolism, but will also help us develop quantitative tools to study other gas-mediated microbial interactions.