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Effects of Pichia kluyveri killer toxin on sensitive cells
Abstract:
The killer toxin produced by Pichia kluyveri 1002 kills yeast strains of the genera Candida, Saccharomyces and Torulopsis, including several S. cerevisiae killer strains. Binding of a lethal amount of the toxin to cells of S. cerevisiae SCF 1717 occurs rapidly after toxin addition. After treatment with the toxin for 10 min sensitive cells partially recovered when incubated under conditions that favor protein synthesis. Only after a lag time of 50--90 min sensitive cells changed physiologically. Killing of sensitive cells was characterized by leakage of potassium and adenosine 5'-triphosphate, decrease of intracellular pH, and inhibition of the active uptake of amino acids. These effects coincided with cell shrinkage and varied with incubation conditions. Uptake of the amino acid leucine in sensitive cells involved two apparently distinct transport systems (Km1 = 0.04 mM; Km2 = 0.46 mM). The toxin showed different effects on these transport systems.
Insights
Pichia kluyveri toxin kills sensitive yeast strains by disrupting cell integrity and nutrient uptake. Physiological changes and cell death occur after a significant lag period, impacting potassium and ATP levels.
Area of Science:
- * Mycology
- * Biochemistry
- * Cell Biology
Background:
- * The yeast Pichia kluyveri produces a killer toxin with activity against various yeast species.
- * Understanding the mechanism of action of yeast killer toxins is crucial for applications in fermentation and antifungal research.
Purpose of the Study:
- * To investigate the killing mechanism of the Pichia kluyveri 1002 toxin on sensitive yeast strains.
- * To characterize the physiological changes and cellular damage induced by the toxin.
Main Methods:
- * Incubation of sensitive yeast strains (Saccharomyces cerevisiae) with P. kluyveri toxin.
- * Monitoring of cell viability, potassium and adenosine 5'-triphosphate leakage, intracellular pH, and amino acid uptake.
- * Analysis of leucine transport systems in toxin-treated cells.
Main Results:
- * Toxin binding to S. cerevisiae cells was rapid, but significant physiological changes and cell death occurred after a 50-90 min lag phase.
- * Killing involved potassium and adenosine 5'-triphosphate leakage, decreased intracellular pH, and inhibited amino acid uptake.
- * The toxin differentially affected the two identified leucine transport systems in sensitive yeast cells.
Conclusions:
- * The P. kluyveri toxin induces cell death through a multi-step process involving membrane damage and metabolic disruption.
- * The toxin's specific effects on amino acid transport systems warrant further investigation for potential biotechnological applications.