Molecular mechanism of flocculation self-recognition in yeast and its role in mating and survival

Saccharomyces cerevisiae flocculation occurs when fermentable sugars are limiting and is therefore considered as a way to enhance the survival chance of Flo-expressing yeast cells. In this paper the role of Flo1p in mating was demonstrated by showing that the mating efficiency which contributes to the increased survival rate as well by generating genetic variability is increased when cells flocculate. This was revealed by liquid growth experiments in a low shear environment and differential transcriptome analysis of FLO1 expressing cells compared to the non-flocculent wild-type cells. The results show that a floc provides a uniquely organized multicellular ultrastructure that provides a suitable microenvironment to induce and perform cell conjugation. S. cerevisiae strains BY4742 WT BY4742::FLO8 and BY4742 [FLO1] were grown in microgravity and 1-g. A transcriptomic analysis was performed and the transcriptome data were integrated with the high quality protein-protein interaction networks. The identified high score sub-networks (qvalue < 0.001) were considered and further evaluated concerning their GO enrichment using a hypogeometric test.