Abstract
Pseudohyphal growth is a multicellular phenotype naturally performed by wild budding yeast cells in response to stress. Unicellular yeast cells undergo gross changes in their gene regulation and elongate to form branched filament structures consisting of connected cells. Here, we construct synthetic gene regulation systems to enable external induction of pseudohyphal growth in Saccharomyces cerevisiae. By controlling the expression of the natural PHD1 and FLO8 genes we are able to trigger pseudohyphal growth in both diploid and haploid yeast, even in different types of rich media. Using this system, we also investigate how members of the BUD gene family control filamentation in haploid cells. Finally, we employ a synthetic genetic timer network to control pseudohyphal growth and further explore the reversibility of differentiation. Our work demonstrates that synthetic regulation can exert control over a complex multigene phenotype and offers opportunities for rationally modifying the resulting multicellular structure.
Highlights
Pseudohyphal growth is a multicellular phenotype naturally performed by wild budding yeast cells in response to stress
We showed that the simplest multicellular phenotype that is normally triggered by stress in S. cerevisiae—
To construct a synthetic gene network to independently induce filamentation in rich media we chose to target the PHD1 and FLO8 master regulator genes. Both the Phd[1] and Flo[8] proteins are involved in the pseudohyphal growth cascade of the cAMPPKA pathway and act as transcriptional regulators of the MUC1/ FLO11 gene that encodes for a flocculin that plays a central role in pseudohyphal growth and in other yeast multicellular phenotypes (Fig. 1)[5,13]
Summary
Pseudohyphal growth is a multicellular phenotype naturally performed by wild budding yeast cells in response to stress. Unicellular organisms offer the advantage of being reliable and easy to genetically manipulate, while not naturally displaying multicellular phenotypes in rich growth media One such organism is Saccharomyces cerevisiae yeast, which can display a variety of characteristics normally associated with multicellularity, specialization, and pattern formation. Pseudohyphal growth is a highly complex phenotype that involves a large number of processes including substrate adhesion, bud site selection and cell morphogenesis[7] Both haploid and diploid yeast cells create kinds of pseudohyphae formation as a stress response the underlying genetic and morphological differences between the two cell types during the expression of this response leads to a distinction. We showed that the simplest multicellular phenotype that is normally triggered by stress in S. cerevisiae—
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