Transcriptome adaptations of Saccharomyces cerevisiae K1 killer strains KIM01 and KIM01c in response to viral killer toxin K1. Host cell adaptions to K1 toxin

The killer phenomenon in yeast not only provides the opportunity to study host-virus interactions in a eukaryotic model but also represents a powerful tool to analyse potential co-evolutionary events and the role of killer yeast in biological diversity. Although undoubtedly having a crucial impact on abundance and expression of the killer phenotype and killer-yeast harbouring communities in nature, the influence of the particular killer toxin on the producing cells has not been addressed sufficiently. In this study, we describe a model system of two K1 killer yeast strains with distinct differences pointing to substantial selection pressure in response to the toxin secretion level. Transcriptome and lipidome analyses revealed specific intrinsic adaptions of the host cell dependent on the amount of K1 toxin produced. High basal expression of genes coding for osmoprotectants and stress-responsive proteins in a killer secreting higher amounts of active K1 toxin implies a generally increased stress tolerance. Moreover, the data suggest that immunity of the host cell against its own toxin is essential for the sensitive interplay between viruses and host cells providing valuable hints to elucidate the molecular mechanisms underlying K1 immunity and implicating an evolutionarily conserved role for toxin immunity in natural yeast populations.