Analysis of Yeast Killer Toxin K1 Precursor Processing via Site-Directed Mutagenesis: Implications for Toxicity and Immunity.
Stefanie GierManfred J SchmittFrank BreinigPublished in: mSphere (2020)
K1 represents a heterodimeric A/B toxin secreted by virus-infected Saccharomyces cerevisiae strains. In a two-staged receptor-mediated process, the ionophoric activity of K1 leads to an uncontrolled influx of protons, culminating in the breakdown of the cellular transmembrane potential of sensitive cells. K1 killer yeast necessitate not only an immunity mechanism saving the toxin-producing cell from its own toxin but, additionally, a molecular system inactivating the toxic α subunit within the secretory pathway. In this study, different derivatives of the K1 precursor were constructed to analyze the biological function of particular structural components and their influence on toxin activity as well as the formation of protective immunity. Our data implicate an inactivation of the α subunit during toxin maturation and provide the basis for an updated model of K1 maturation within the host cell's secretory pathway.IMPORTANCE The killer phenotype in the baker's yeast Saccharomyces cerevisiae relies on two double-stranded RNA viruses that are persistently present in the cytoplasm. As they carry the same receptor populations as sensitive cells, killer yeast cells need-in contrast to various bacterial toxin producers-a specialized immunity mechanism. The ionophoric killer toxin K1 leads to the formation of cation-specific pores in the plasma membrane of sensitive yeast cells. Based on the data generated in this study, we were able to update the current model of toxin processing, validating the temporary inactivation of the toxic α subunit during maturation in the secretory pathway of the killer yeast.
Keyphrases
- saccharomyces cerevisiae
- escherichia coli
- induced apoptosis
- cell cycle arrest
- single cell
- oxidative stress
- endoplasmic reticulum stress
- machine learning
- magnetic resonance imaging
- computed tomography
- electronic health record
- signaling pathway
- mesenchymal stem cells
- crispr cas
- big data
- risk assessment
- contrast enhanced
- single molecule
- data analysis
- structure activity relationship