Transcriptional regulation of the isocitrate lyase encoding gene in Saccharomyces cerevisiae

Abstract

In this work, we studied the transcriptional regulation of isocitrate lyase synthesis. In Northern blot analyses we first showed that the steady-state ICLl mRNA levels depend on the carbon source used for growth. In addition, we determined the kinetics of transcriptional repression upon a shift of ethanol-grown cells to glucose and of the induction when cells were transferred from glucose to ethanol. By deletion analyses as well as by studying the influence on expression of different fragments cloned into the heterologous CYCZ promoter lacking its own UAS sequences, we defined UAS and URS elements in the ICLI promoter. A region mediating the control by CAT3, a gene also involved in the control of expression of other genes subject to carbon catabolite repression, was found to overlap with one of these CJAS elements.

Transcriptional regulation of the yeast vacuolar aminopeptidase yscI encoding gene (APE1) by carbon sources

“…Only a weak band was observed after growth of yeast cells on glycerol or acetate. These results are similar to those reported for other genes regulated by catabolite repression [22][23][24][25]. The kinetics of carbon catabolite repression by glucose on APE1 m-RNA levels are shown in Fig.…”

“…Loss of the hexokinase PII isozyme causes the cell to become resistant to glucose-mediated repression of a number of genes (reviewed in [1]). On the other hand, CAT1 encodes a protein kinase [37] necessary for derepression of several genes after a shift of cells to non-fermentable carbon sources [1,25]. Therefore we examined RNA prepared from hxk2 as well as from cat1 mutants for the presence of the APE1 transcript by Northern blot analysis.…”

GABA transaminases from Saccharomyces cerevisiae and Arabidopsis thaliana complement function in cytosol and mitochondria

“…Since yeast cells growing on glucose as carbon source produce significant levels of glyoxylate (Devantier et al, 2005;Villas-Boas et al, 2006), the use of glyoxylate rather than pyruvate cannot be ruled out. However, yeast cells growing on glucose produce glyoxylate from glycine using alanine: glyoxylate aminotransferase (AGX1p) (Villas-Boas et al, 2005), since glucose represses the glyoxylate glyoxylate cycle, the only other pathway for glyoxylate production (Takada and Noguchi, 1985;Fernandez et al, 1993;Maaheimo et al, 2001;López et al, 2004). If ectopically expressed AtGABA-T used glyoxylate rather than pyruvate with GABA to produce glycine rather than alanine and SSA, the endogenous AGX1p protein would then cycle the glycine back to glyoxylate, consuming a pyruvate and producing an alanine in the process.…”

Glucose‐induced inactivation of isocitrate lyase in Saccharomyces cerevisiae is mediated by an internal decapeptide sequence

“…2A construct 2). The third construct has been described elsewhere [10], a BamHI-HindlII fragment containing 1000 nucleotides from the 5' non coding region and 171 bp of the ICL1 coding sequence was cloned in frame to lacZ into YIp356.…”

“…This gene was employed in order to study the transcriptional regulation of its expression. Thus, promoter elements necessary for glucose repression were delimited [10,11 ]. Once transcription and translation had taken place, addition of glucose to cells growing on a medium with ethanol as the carbon source causes a time-dependent disappearance of ICLase.…”