Control of Saccharomyces cerevisiae carboxypeptidase S (CPS1) gene expression under nutrient limitation.
Expression of the vacuolar carboxypeptidase S (CPS1) gene in Saccharomyces cerevisiae is regulated by the availability of nutrients. Enzyme production is sensitive to nitrogen catabolite repression; i.e. the presence of ammonium ions maintains expression of the gene at a low level. Transfer of ammonium-glucose pre-grown cells to a medium deprived of nitrogen causes a drastic increase in CPS1 RNA level provided that a readily usable carbon source, such as glucose or fructose, is available to the cells. Derepression of the gene by nitrogen limitation is cycloheximide-insensitive. Neither glycerol, ethanol, acetate nor galactose support derepression of CPS1 expression under nitrogen starvation conditions. Non-metabolizable sugar analogs (2-deoxyglucose, 6-methyl-glucose or glucosamine) do not allow derepression of CPS1, showing that the process is energy-dependent. Production of carboxypeptidase yscS also increases several-fold when ammonium-pregrown cells are transferred to media containing glucose and a non-readily metabolizable nitrogen source such as proline, leucine, valine or leucyl-glycine. Analysis of CPS1 expression in RAS2+ (high cAMP) and ras2 mutant (low cAMP) strains and in cells grown at low temperature (23 degrees C) and in heat-shocked cells (38 degrees C) shows that steady-state levels of CPS1 mRNA are not controlled by a low cAMP level-signalling pathway.
Departamento de Biología Funcional, Universidad de Oviedo, Spain.
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Suárez-Rendueles
D000262:Adenylyl Cyclases / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D002268:Carboxypeptidases / Q000096:biosynthesis*; D004734:Energy Metabolism; D004794:Enzyme Repression; D005656:Fungal Proteins / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D009005:Monosaccharides / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000201:enzymology; D018631:ras Proteins
D005656:Fungal Proteins; D009005:Monosaccharides; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D002244:Carbon; D002268:Carboxypeptidases; C019836:CPS1 protein, S cerevisiae; C489015:RAS2 protein, S cerevisiae; D018631:ras Proteins; D000262:Adenylyl Cyclases; D009584:Nitrogen