Related Experiment Video
Updated: Nov 21, 2025
Identification of Host Pathways Targeted by Bacterial Effector Proteins using Yeast Toxicity and Suppressor Screens
Published on: October 25, 2019
The Viral K1 Killer Yeast System: Toxicity, Immunity, and Resistance
Angelina Chan1, Michelle Hays1, Gavin Sherlock1
1Department of Genetics, Stanford University, Stanford, California, USA.
Abstract:
Killer yeasts, such as the K1 killer strain of S. cerevisiae, express a secreted anti-competitive toxin whose production and propagation require the presence of two vertically-transmitted dsRNA viruses. In sensitive cells lacking killer virus infection, toxin binding to the cell wall results in ion pore formation, disruption of osmotic homeostasis, and cell death. However, the exact mechanism(s) of K1 toxin killing activity, how killer yeasts are immune to their own toxin, and which factors could influence adaptation and resistance to K1 toxin within formerly sensitive populations are still unknown. Here, we describe the state of knowledge about K1 killer toxin, including current models of toxin processing and killing activity, and a summary of known modifiers of K1 toxin immunity and resistance. In addition, we discuss two key signaling pathways, HOG (high osmolarity glycerol) and CWI (cell wall integrity), whose involvement in an adaptive response to K1 killer toxin in sensitive cells has been previously documented but requires further study. As both host-virus and sensitive-killer competition have been documented in killer systems like K1, further characterization of K1 killer yeasts may provide a useful model system for study of both intracellular genetic conflict and counter-adaptation between competing sensitive and killer populations.
Insights
Killer yeasts secrete toxins to compete, but how they kill and how resistance develops is unclear. This study reviews K1 toxin knowledge and discusses pathways involved in adaptation and resistance.
Area of Science:
- Microbiology
- Molecular Biology
- Yeast Genetics
Background:
- Killer yeasts, like Saccharomyces cerevisiae K1 strain, produce secreted toxins dependent on dsRNA viruses.
- These toxins disrupt osmotic balance and cause cell death in sensitive yeast populations.
- Mechanisms of K1 toxin lethality, killer immunity, and resistance evolution remain largely unknown.
Purpose of the Study:
- To review current knowledge on K1 killer toxin processing and activity.
- To summarize factors influencing K1 toxin immunity and resistance.
- To highlight the potential role of HOG and CWI signaling pathways in adaptive responses.
Main Methods:
- Literature review of K1 killer toxin research.
- Analysis of existing models for toxin activity and immunity.
- Discussion of signaling pathways (HOG, CWI) involved in yeast adaptation.
Main Results:
- Current models of K1 toxin processing and killing activity are presented.
- Known modifiers of K1 toxin immunity and resistance are summarized.
- The involvement of HOG and CWI pathways in adaptive responses is discussed.
Conclusions:
- Further research on K1 killer yeasts can elucidate intracellular genetic conflict and population counter-adaptation.
- Understanding K1 toxin mechanisms is crucial for studying host-virus interactions and competitive dynamics.
- K1 killer yeast systems offer a model for exploring evolutionary adaptation and resistance strategies.
More Related Videos
Related Concept Videos
01:40Cell-mediated Immune Responses
01:29Immune Response Against Viral Pathogens
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...
01:27Cytotoxic T Cells-mediated Immune Response
Immunological surveillance is the ability of immune cells to monitor and eliminate infected cells with intracellular pathogens, neoplastically transformed cells, and cells with non-self antigens. Cytotoxic T cells and NK...
01:31Defense Against Bacterial Pathogens
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
01:20Special Features of Adaptive Immunity
The primary cell types involved in adaptive immunity are T cells and B cells. Each type has a unique role in defending the body against pathogens. T cells are responsible for cell-mediated immunity. They identify and eliminate infected cells directly,...
01:28Yeast Signaling