Mechanisms Underlying Cell-to-Cell Diversity in Clonal Populations of Yeast By

Abstract | The FLO promoters are among the largest promoters in yeast and receive a complex combination of signals from upstream signaling pathways through their association with downstream DNA binding factors and chromatin remodelers. The genes regulated by these promoters encode cell-surface glycoproteins that mediate a range of cell-to-cell and cell-to-surface adhesions. Phenotypic diversity in clonal populations of yeast cells is mediated in part by epigenetic silencing of the FLO10 and FLO11 promoters. Silencing of the FLO promoters is heterogeneous, or variegated, within a clonal population of cells. The variegated transcription of FLO10 and FLO11 results in a population of yeast cells that exhibits cell-to-cell variability in flocculation, adhesion to and invasion of inert surfaces, and filamentous growth. In this thesis, I discuss chromatin modifying proteins that localize to the FLO10 and FLO11 promoters and act in trans to affect transcription and silencing at these promoters. I describe the results of genome