Bipolarity of the Saccharomyces cerevisiae genome

Accumulating evidence indicates that eukaryotic genes tend to belong in two distinct categories that we will call class I and class II. Class I genes do not contain a TATA box in their promoter, and have low expression variability both at the single cell level (in constant environment) and at the population level (in changing environmental conditions). In contrast, class II genes contain a TATA box in their promoter, and tend to have pronounced expression variability both at the single cell level (in constant environment) and at the population level (in changing environmental conditions). Here we show that the positioning and regulation of class I and class II genes is strikingly different in the large-scale transcriptional regulatory (TR) network of S. cerevisiae. We also show that class I and class II genes differ dramatically in several properties, including gene expression variability at diverse time scales and population sizes, mutational variance, gene essentiality and subcellular localization. This dichotomy might indicate that evolution placed different genes in different locations within the cell and within the TR network, according to some fundamental principles that govern cellular information processing and survival in a changing environment.