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Membrane-mediated killing of Saccharomyces cerevisiae by glycoproteins from Torulopsis glabrata
Abstract:
Cell-free supernatants from cultures of Torulopsis glabrata contained glycoprotein toxins that killed sensitive and killer strains of Saccharomyces cerevisiae with single-hit kinetics. Growing S. cerevisiae treated with the toxins showed a leakage of cellular potassium, partial dissipation of the adenosine triphosphate pool, and a coordinate shutdown of macromolecular synthesis. These pool efflux-stimulating toxins have been partially purified and at least three toxic glycoproteins have been separated. Pool efflux-stimulating toxin activity was stable from pH 3 through 7, though killing was maximal close to pH 4.
Insights
Torulopsis glabrata secretes glycoprotein toxins that kill Saccharomyces cerevisiae by causing potassium and adenosine triphosphate (ATP) pool leakage, halting cellular synthesis. Three distinct toxic glycoproteins were identified, active between pH 3-7, with peak toxicity near pH 4.
Area of Science:
- Microbiology
- Biochemistry
- Cell Biology
Background:
- Torulopsis glabrata produces toxins affecting Saccharomyces cerevisiae.
- Understanding yeast-toxin interactions is crucial for industrial and research applications.
Purpose of the Study:
- To characterize the toxins produced by Torulopsis glabrata.
- To investigate the mechanism of toxicity against Saccharomyces cerevisiae.
Main Methods:
- Cell-free supernatants from Torulopsis glabrata cultures were analyzed.
- Sensitive and killer strains of Saccharomyces cerevisiae were exposed to toxins.
- Potassium leakage, adenosine triphosphate (ATP) pool, and macromolecular synthesis were measured.
- Toxic glycoproteins were partially purified and separated.
Main Results:
- Glycoprotein toxins from T. glabrata exhibited single-hit kinetics against S. cerevisiae.
- Toxin exposure led to potassium efflux, ATP pool depletion, and inhibited macromolecular synthesis.
- At least three distinct toxic glycoproteins were isolated.
- Toxin activity was stable from pH 3-7, with maximal killing observed near pH 4.
Conclusions:
- T. glabrata secretes potent glycoprotein toxins targeting S. cerevisiae.
- These toxins disrupt cellular homeostasis by inducing pool efflux and inhibiting synthesis.
- The identified toxins represent a novel mechanism of inter-yeast antagonism.