Variation, Variegation and Heritable Gene Repression in S. cerevisiae

Abstract

Phenotypic heterogeneity provides growth advantages for a population upon changes of the environment. In S. cerevisiae, such heterogeneity has been observed as “on/off” states in the expression of individual genes in individual cells. These variations can persist for a limited or extended number of mitotic divisions. Such traits are known to be mediated by heritable chromatin structures, by the mitotic transmission of transcription factors involved in gene regulatory circuits or by the cytoplasmic partition of prions or other unstructured proteins. The significance of such epigenetic diversity is obvious, however, we have limited insight into the mechanisms that generate it. In this review, we summarize the current knowledge of epigenetically maintained heterogeneity of gene expression and point out similarities and converging points between different mechanisms. We discuss how the sharing of limiting repression or activation factors can contribute to cell-to-cell variations in gene expression and to the coordination between short- and long- term epigenetic strategies. Finally, we discuss the implications of such variations and strategies in adaptation and aging.

Spontaneous Attenuation of Alcoholic Fermentation via the Dysfunction of Cyc8p in Saccharomyces cerevisiae

“…In multicellular organisms, a single-origin cell proliferates and differentiates into a variety of cell types. Even unicellular organisms, such as the model eukaryote Saccharomyces cerevisiae , genetically or epigenetically generate phenotypic heterogeneity in growth rate, stress response, gene expression, and cellular metabolism within a population [ 1 , 2 , 3 , 4 , 5 ]. Studies of metabolic diversity in S. cerevisiae have achieved significant impacts over the years because of their broad implications, ranging from tumor biology to applied microbiology [ 6 , 7 , 8 ].…”