Effect of overexpression of yeast Ppz1 protein phosphatase on gene remodeling in response to changes in carbon source

Our previous results (Calafi et al 2020; PMID: 32339526) demonstrated a defect in cell proliferation when PPZ1 was overexpressed under the control of a tetO-based promoter that was, up to some extent, dependent of the availability of glucose. To further investigate this phenomenon, we have determined the transcriptional response triggered by the shift form high to low glucose, or to galactose, in normal cells and in cells overexpressing PPZ1 from the tetO7–driven multicopy pCM190 plasmid. Our data suggest that, under these circumstances, overexpression of Ppz1 interferes with the proper activation of a set of genes mainly involved in carbon metabolism, thus impairing the normal transcriptional adaptation to conditions in which glucose becomes limiting. Overall design: Two different types of BY4741-based yeast cells were used: 1) cells containing the empty pCM190 plasmid and 2) cells carrying the same pCM190 plasmid with the PPZ1 coding region under control of the doxycycline-repressed tetO7 promoter. Both types of cells were shifted to medium containing 2% glucose, 0.25% glucose or 2% galactose, and grown for 1h before sample collection.