NUTRITIONAL UPSHIFT RESPONSE OF RIBOSOMAL-PROTEIN GENE-TRANSCRIPTION IN SACCHAROMYCES-CEREVISIAE

Switching Saccharomyces cerevisiae from non-fermentative to fermentati ve growth by adding glucose to a medium with glycerol as the sole carb on source, leads to a sudden increase in the rate of ribosomal protein gene transcription. By analyzing the nutritional shift response in a variety of yeast mutants and in the presence of different drugs, evide nce was obtained that: (i) no de novo protein synthesis is required fo r this response; (ii) protein kinase A is essential, though independen t of intracellular levels of cAMP, whereas protein kinase C is not inv olved; (iii) proper regulation of sugar phosphorylation is essential; (iv) glycolysis is required for the long term effect of the nutritiona l upshift; and (v) pathways leading to glucose-induced activation diff er from those leading to gene repression, probably already at the leve l of glucose transport.