The touch of death: killer mediated contact inhibition and Hsp12p secretion determines differential fitness in a community of grape yeast isolates

The budding yeast Saccharomyces cerevisiae represents the best-understood and most powerful genetic model systems as its genome was the first, out of all the eukaryotic organisms, to be completely sequenced. Recently it has been possible to establish an interaction between genotype and environment to describe fitness in terms of better adaptation to stress. Lately, several disciplines have converged to turn S. cerevisiae into a model for the genetic study of ecology and evolution. During wine production, the yeast strains with the best fitness establish strategies to compete for spaces and resources, dominating the natural microbial ecosystems, although it is also possible that they establish behaviours that contribute to intraspecies coexistence. Little is known about the genes and their transcripts responsible for ecological interactions (cooperation and competition) among yeasts. To fill this gap, we performed a genome-wide analysis of two natural yeast strains. Our findings demonstrate that both Heat Shock Protein 12 (Hsp12p) and PAU genes are not only important for the fitness of the yeast during fermentation, but are also fundamental for cooperation and competition behaviours, respectively. The results highlight the existence of previously unknown cooperative comportment dependent on the secreted Hsp12p, counter-balanced by contact-dependent killer inhibition. This work represents a good approach to the use of the yeast S. cerevisiae as a model to improve our understanding in the study of the genetics of the ecology