Contribution in edited book
Antagonistic Interactions and Killer Yeasts

Publication Details
Klassen, R.; Schaffrath, R.; Buzzini, P.; Ganter, P.
Buzzini, Pietro; Lachance, Marc-André; Yurkov, Andrey
Springer International Publishing
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Book title:
Yeasts in Natural Ecosystems: Ecology

Antagonistic interactions occur between yeasts and other competing microorganisms. These interactions may rely on non-proteinaceous compounds or proteins called killer toxins. A large variety of structurally and functionally diverse toxins released from killer yeasts are known. In addition to chromosomally encoded toxins, several well-characterized toxins are encoded by selfish extrachromosomal DNA or RNA molecules of viral origin. Despite their structural diversity, only a handful of toxic strategies are utilized by structurally distinct killer toxins, and multistep modes of cell killing involve common steps, such as the binding of different cell wall receptors. In addition, distinct toxin types are known to rely on common mechanisms for maturation, structural stabilization, and release from producer cells. In case of the extrachromosomally encoded toxins, specific immunity mechanisms are linked to toxin production. In these cases, toxins are assumed to provide a positive selection mechanism for the genetic system encoding both toxin and immunity. Hence, release of killer toxins might benefit both the toxin producer and the selfish genetic element in the producer cell. Killer yeasts display broad taxonomic diversity, including basidiomycetes and ascomycetes. Target species may not only include yeasts of both fungal phyla but also other microorganisms such as bacteria or protozoa that may compete in certain natural habitats with the killer yeast. Although killer systems are assumed to be competitive mechanisms, their role in natural yeast communities is not yet well understood. Theoretical approaches have, in general, failed to predict the coexistence of killer, non-killer, and target strains that occurs with regularity in nature. The few empirical studies of natural killer systems have confirmed the ecological importance of killer toxins but have uncovered differences in the exact role the toxins play in yeast ecology.


Last updated on 2019-24-07 at 08:55