scholarly journals Null mutations in the SNF3 gene of Saccharomyces cerevisiae cause a different phenotype than do previously isolated missense mutations.

1986 ◽  
Vol 6 (11) ◽  
pp. 3569-3574 ◽  
Author(s):  
L Neigeborn ◽  
P Schwartzberg ◽  
R Reid ◽  
M Carlson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Uptake ◽  
Gene Disruption ◽  
Glucose Repression ◽  
Gene Products ◽  
Missense Mutations ◽  
Chromosomal Locus ◽  
Growth Properties ◽  
Invertase Gene ◽  
Regulatory Functions

Missense mutations in the SNF3 gene of Saccharomyces cerevisiae were previously found to cause defects in both glucose repression and derepression of the SUC2 (invertase) gene. In addition, the growth properties of snf3 mutants suggested that they were defective in uptake of glucose and fructose. We have cloned the SNF3 gene by complementation and demonstrated linkage of the cloned DNA to the chromosomal SNF3 locus. The gene encodes a 3-kilobase poly(A)-containing RNA, which was fivefold more abundant in cells deprived of glucose. The SNF3 gene was disrupted at its chromosomal locus by several methods to create null mutations. Disruption resulted in growth phenotypes consistent with a defect in glucose uptake. Surprisingly, gene disruption did not cause aberrant regulation of SUC2 expression. We discuss possible mechanisms by which abnormal SNF3 gene products encoded by missense alleles could perturb regulatory functions.

Null mutations in the SNF3 gene of Saccharomyces cerevisiae cause a different phenotype than do previously isolated missense mutations

1986 ◽  
Vol 6 (11) ◽  
pp. 3569-3574
Author(s):  
L Neigeborn ◽  
P Schwartzberg ◽  
R Reid ◽  
M Carlson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Uptake ◽  
Gene Disruption ◽  
Glucose Repression ◽  
Gene Products ◽  
Missense Mutations ◽  
Chromosomal Locus ◽  
Growth Properties ◽  
Invertase Gene ◽  
Regulatory Functions

Missense mutations in the SNF3 gene of Saccharomyces cerevisiae were previously found to cause defects in both glucose repression and derepression of the SUC2 (invertase) gene. In addition, the growth properties of snf3 mutants suggested that they were defective in uptake of glucose and fructose. We have cloned the SNF3 gene by complementation and demonstrated linkage of the cloned DNA to the chromosomal SNF3 locus. The gene encodes a 3-kilobase poly(A)-containing RNA, which was fivefold more abundant in cells deprived of glucose. The SNF3 gene was disrupted at its chromosomal locus by several methods to create null mutations. Disruption resulted in growth phenotypes consistent with a defect in glucose uptake. Surprisingly, gene disruption did not cause aberrant regulation of SUC2 expression. We discuss possible mechanisms by which abnormal SNF3 gene products encoded by missense alleles could perturb regulatory functions.

scholarly journals Structure and expression of the SNF1 gene of Saccharomyces cerevisiae.

1984 ◽  
Vol 4 (1) ◽  
pp. 54-60 ◽  
Author(s):  
J L Celenza ◽  
M Carlson
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Gene Product ◽  
Gene Disruption ◽  
Glucose Repression ◽  
Regulation Of Gene Expression ◽  
Null Mutation ◽  
Chromosomal Locus ◽  
Cloned Gene ◽  
External Glucose

The SNF1 gene of Saccharomyces cerevisiae is essential for normal regulation of gene expression by glucose repression. A functional SNF1 gene product is required to derepress many glucose-repressible genes in response to conditions of low external glucose. In the case of the SUC2 structural gene for invertase, SNF1 acts at the RNA level. We have reported the isolation of a cloned gene that complements the snf1 defect in S. cerevisiae and that is homologous to DNA at the SNF1 locus (J. L. Celenza and M. Carlson, Mol. Cell. Biol. 4:49-53, 1984). In this work we identified a 2.4-kilobase polyadenylate-containing RNA encoded by the SNF1 gene and showed that its level is neither regulated by glucose repression nor dependent on a functional SNF1 product. The position of the SNF1 RNA relative to the cloned DNA was mapped, and the direction of transcription was determined. The cloned DNA was used to disrupt the SNF1 gene at its chromosomal locus. Gene disruption resulted in A Snf1- phenotype, thereby proving that the cloned gene is the SNF1 gene and showing that the phenotype of a true null mutation is indistinguishable from that of previously isolated snf1 mutations.

Structure and expression of the SNF1 gene of Saccharomyces cerevisiae

1984 ◽  
Vol 4 (1) ◽  
pp. 54-60
Author(s):  
J L Celenza ◽  
M Carlson
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Gene Product ◽  
Gene Disruption ◽  
Glucose Repression ◽  
Regulation Of Gene Expression ◽  
Null Mutation ◽  
Chromosomal Locus ◽  
Cloned Gene ◽  
External Glucose

The SNF1 gene of Saccharomyces cerevisiae is essential for normal regulation of gene expression by glucose repression. A functional SNF1 gene product is required to derepress many glucose-repressible genes in response to conditions of low external glucose. In the case of the SUC2 structural gene for invertase, SNF1 acts at the RNA level. We have reported the isolation of a cloned gene that complements the snf1 defect in S. cerevisiae and that is homologous to DNA at the SNF1 locus (J. L. Celenza and M. Carlson, Mol. Cell. Biol. 4:49-53, 1984). In this work we identified a 2.4-kilobase polyadenylate-containing RNA encoded by the SNF1 gene and showed that its level is neither regulated by glucose repression nor dependent on a functional SNF1 product. The position of the SNF1 RNA relative to the cloned DNA was mapped, and the direction of transcription was determined. The cloned DNA was used to disrupt the SNF1 gene at its chromosomal locus. Gene disruption resulted in A Snf1- phenotype, thereby proving that the cloned gene is the SNF1 gene and showing that the phenotype of a true null mutation is indistinguishable from that of previously isolated snf1 mutations.

Two systems of glucose repression of the GAL1 promoter in Saccharomyces cerevisiae

1990 ◽  
Vol 10 (9) ◽  
pp. 4757-4769
Author(s):  
J S Flick ◽  
M Johnston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Base Pair ◽  
Glucose Repression ◽  
Gene Products ◽  
Gal1 Promoter ◽  
Base Pair Fragment ◽  
Common Signal ◽  
Multiple Sequences ◽  
Pair Fragment ◽  
Gal1 Gene

Expression of the GAL1 gene in Saccharomyces cerevisiae is strongly repressed by growth on glucose. We show that two sites within the GAL1 promoter mediate glucose repression. First, glucose inhibits transcription activation by GAL4 protein through UASG. Second, a promoter element, termed URSG, confers glucose repression independently of GAL4. We have localized the URSG sequences responsible for glucose repression to an 87-base-pair fragment located between UASG and the TATA box. Promoters deleted for small (20-base-pair) segments that span this sequence are still subject to glucose repression, suggesting that there are multiple sequences within this region that confer repression. Extended deletions across this region confirm that it contains at least two and possibly three URSG elements. To identify the gene products that confer repression upon UASG and URSG, we have analyzed glucose repression mutants and found that the GAL83, REG1, GRR1, and SSN6 genes are required for repression mediated by both UASG and URSG. In contrast, GAL82 and HXK2 are required only for UASG repression. A mutation designated urr1-1 (URSG repression resistant) was identified that specifically relieves URSG repression without affecting UASG repression. In addition, we observed that the SNF1-encoded protein kinase is essential for derepression of both UASG and URSG. We propose that repression of UASG and URSG is mediated by two independent pathways that respond to a common signal generated by growth on glucose.

scholarly journals Rgt1, a glucose sensing transcription factor, is required for transcriptional repression of the HXK2 gene in Saccharomyces cerevisiae

2005 ◽  
Vol 388 (2) ◽  
pp. 697-703 ◽  
Author(s):  
Aaron PALOMINO ◽  
Pilar HERRERO ◽  
Fernando MORENO
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transcription Factor ◽  
Transcriptional Repression ◽  
Glucose Repression ◽  
Fold Increase ◽  
Glucose Sensing ◽  
Start Codon ◽  
Dependent Manner ◽  
Gene Encoding ◽  
Regulatory Functions

Expression of HXK2, a gene encoding a Saccharomyces cerevisiae bifunctional protein with catalytic and regulatory functions, is controlled by glucose availability, being activated in the presence of glucose and inhibited when the levels of the sugar are low. In the present study, we identified Rgt1 as a transcription factor that, together with the Med8 protein, is essential for repression of the HXK2 gene in the absence of glucose. Rgt1 represses HXK2 expression by binding specifically to the motif (CGGAAAA) located at −395 bp relative to the ATG translation start codon in the HXK2 promoter. Disruption of the RGT1 gene causes an 18-fold increase in the level of HXK2 transcript in the absence of glucose. Rgt1 binds to the RGT1 element of HXK2 promoter in a glucose-dependent manner, and the repression of target gene depends on binding of Rgt1 to DNA. The physiological significance of the connection between two glucose-signalling pathways, the Snf3/Rgt2 that causes glucose induction and the Mig1/Hxk2 that causes glucose repression, was also analysed.

scholarly journals Suppressors reveal two classes of glucose repression genes in the yeast Saccharomyces cerevisiae.

Genetics ◽  
1994 ◽  
Vol 136 (4) ◽  
pp. 1271-1278 ◽  
Author(s):  
J R Erickson ◽  
M Johnston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Repression ◽  
Single Gene ◽  
The Other ◽  
Gene Products ◽  
Yeast Saccharomyces Cerevisiae ◽  
Similar Point ◽  
Normal Glucose ◽  
Gal Genes ◽  
Extragenic Suppressors

Abstract We selected and analyzed extragenic suppressors of mutations in four genes--GRR1, REG1, GAL82 and GAL83-required for glucose repression of the GAL genes in the yeast Saccharomyces cerevisiae. The suppressors restore normal or nearly normal glucose repression of GAL1 expression in these glucose repression mutants. Tests of the ability of each suppressor to cross-suppress mutations in the other glucose repression genes revealed two groups of mutually cross-suppressed genes: (1) REG1, GAL82 and GAL83 and (2) GRR1. Mutations of a single gene, SRG1, were found as suppressors of reg1, GAL83-2000 and GAL82-1, suggesting that these three gene products act at a similar point in the glucose repression pathway. Mutations in SRG1 do not cross-suppress grr1 or hxk2 mutations. Conversely, suppressors of grr1 (rgt1) do not cross-suppress any other glucose repression mutation tested. These results, together with what was previously known about these genes, lead us to propose a model for glucose repression in which Grr1p acts early in the glucose repression pathway, perhaps affecting the generation of the signal for glucose repression. We suggest that Reg1p, Gal82p and Gal83p act after the step(s) executed by Grr1p, possibly transmitting the signal for repression to the Snf1p protein kinase.

The Saccharomyces cerevisiae ADR1 gene is a positive regulator of transcription of genes encoding peroxisomal proteins

1991 ◽  
Vol 11 (2) ◽  
pp. 699-704 ◽  
Author(s):  
M Simon ◽  
G Adam ◽  
W Rapatz ◽  
W Spevak ◽  
H Ruis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Repression ◽  
Northern Hybridization ◽  
Multicopy Plasmid ◽  
Beta Oxidation ◽  
Positive Regulator ◽  
Ethanol Medium ◽  
Genes Encoding ◽  
Multiple Copies ◽  
Regulatory Functions

Expression of the CTA1 gene of Saccharomyces cerevisiae, encoding catalase A, the peroxisomal catalase of this yeast, is sensitive to glucose repression. A DNA fragment cloned as a multicopy plasmid suppressing the glucose repression of CTA1 transcription was demonstrated to contain the ADR1 gene. Multiple copies of ADR1 increased catalase A formation not only on 10% glucose, but also on ethanol medium and in the presence of oleic acid, an inducer of peroxisome proliferation. Compared with wild-type cells, adr1 null mutants produced by disruption of the gene exhibit reduced CTA1 expression. This demonstrates that ADR1 is a true positive regulator of CTA1. Further experiments showed that it acts directly on CTA1. Alcohol dehydrogenase II, which is under ADR1 control, was excluded as a mediator of the effect on CTA1; deletion of bases -123 to -168 of CTA1 reduces expression and eliminates the response to the ADR1 multicopy plasmid without eliminating fatty acid induction; and gel retardation experiments demonstrated that ADR1 binds to a CTA1 upstream fragment (-156 to -184) with limited similarity to the ADR1 binding site of ADH2. Northern hybridization experiments further demonstrated that expression of two genes encoding enzymes of peroxisomal beta-oxidation (beta-ketothiolase, trifunctional enzyme) and of a gene involved in peroxisome assembly (PAS1) is also negatively affected by the adr1 null mutation. These findings demonstrate that the ADR1 protein has much broader regulatory functions than previously recognized.

scholarly journals Correlation between TCA cycle flux and glucose uptake rate during respiro-fermentative growth of Saccharomyces cerevisiae

Microbiology ◽  
2009 ◽  
Vol 155 (12) ◽  
pp. 3827-3837 ◽  
Author(s):  
Jan Heyland ◽  
Jianan Fu ◽  
Lars M. Blank
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Uptake ◽  
Production Rate ◽  
Environmental Conditions ◽  
Glucose Repression ◽  
Single Gene ◽  
Tca Cycle ◽  
Acetate Production ◽  
The Tca Cycle ◽  
Uptake Rates

Glucose repression of the tricarboxylic acid (TCA) cycle in Saccharomyces cerevisiae was investigated under different environmental conditions using 13C-tracer experiments. Real-time quantification of the volatile metabolites ethanol and CO2 allowed accurate carbon balancing. In all experiments with the wild-type, a strong correlation between the rates of growth and glucose uptake was observed, indicating a constant yield of biomass. In contrast, glycerol and acetate production rates were less dependent on the rate of glucose uptake, but were affected by environmental conditions. The glycerol production rate was highest during growth in high-osmolarity medium (2.9 mmol g−1 h−1), while the highest acetate production rate of 2.1 mmol g−1 h−1 was observed in alkaline medium of pH 6.9. Under standard growth conditions (25 g glucose l−1 , pH 5.0, 30 °C) S. cerevisiae had low fluxes through the pentose phosphate pathway and the TCA cycle. A significant increase in TCA cycle activity from 0.03 mmol g−1 h−1 to about 1.7 mmol g−1 h−1 was observed when S. cerevisiae grew more slowly as a result of environmental perturbations, including unfavourable pH values and sodium chloride stress. Compared to experiments with high glucose uptake rates, the ratio of CO2 to ethanol increased more than 50 %, indicating an increase in flux through the TCA cycle. Although glycolysis and the ethanol production pathway still exhibited the highest fluxes, the net flux through the TCA cycle increased significantly with decreasing glucose uptake rates. Results from experiments with single gene deletion mutants partially impaired in glucose repression (hxk2, grr1) indicated that the rate of glucose uptake correlates with this increase in TCA cycle flux. These findings are discussed in the context of regulation of glucose repression.

scholarly journals Candida albicans Hexokinase 2 Challenges the Saccharomyces cerevisiae Moonlight Protein Model

2021 ◽  
Vol 9 (4) ◽  
pp. 848
Author(s):  
Romain Laurian ◽  
Jade Ravent ◽  
Karine Dementhon ◽  
Marc Lemaire ◽  
Alexandre Soulard ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Glucose Repression ◽  
Carbon Sources ◽  
Metabolic Adaptation ◽  
Dual Function ◽  
Pathogenic Yeast ◽  
Hexokinase 2 ◽  
Regulatory Functions ◽  
The Impact

Survival of the pathogenic yeast Candida albicans depends upon assimilation of fermentable and non-fermentable carbon sources detected in host microenvironments. Among the various carbon sources encountered in a human body, glucose is the primary source of energy. Its effective detection, metabolism and prioritization via glucose repression are primordial for the metabolic adaptation of the pathogen. In C. albicans, glucose phosphorylation is mainly performed by the hexokinase 2 (CaHxk2). In addition, in the presence of glucose, CaHxK2 migrates in the nucleus and contributes to the glucose repression signaling pathway. Based on the known dual function of the Saccharomyces cerevisiae hexokinase 2 (ScHxk2), we intended to explore the impact of both enzymatic and regulatory functions of CaHxk2 on virulence, using a site-directed mutagenesis approach. We show that the conserved aspartate residue at position 210, implicated in the interaction with glucose, is essential for enzymatic and glucose repression functions but also for filamentation and virulence in macrophages. Point mutations and deletion into the N-terminal region known to specifically affect glucose repression in ScHxk2 proved to be ineffective in CaHxk2. These results clearly show that enzymatic and regulatory functions of the hexokinase 2 cannot be unlinked in C. albicans.

scholarly journals Molecular and genetic analysis of the SNF7 gene in Saccharomyces cerevisiae.

Genetics ◽  
1993 ◽  
Vol 135 (1) ◽  
pp. 17-23 ◽  
Author(s):  
J Tu ◽  
L G Vallier ◽  
M Carlson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Analysis ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Chromosomal Locus ◽  
Glucose Limitation ◽  
Suppressor Mutations ◽  
Invertase Gene ◽  
The Right ◽  
Synthetic Phenotype

Abstract Mutations in the SNF7 gene of Saccharomyces cerevisiae prevent full derepression of the SUC2 (invertase) gene in response to glucose limitation. We report the molecular cloning of the SNF7 gene by complementation. Sequence analysis predicts that the gene product is a 27-kDa acidic protein. Disruption of the chromosomal locus causes a fewfold decrease in invertase derepression, a growth defect on raffinose, temperature-sensitive growth on glucose, and a sporulation defect in homozygous diploids. Genetic analysis of the interactions of the snf7 null mutation with ssn6 and spt6/ssn20 suppressor mutations distinguished SNF7 from the SNF2, SNF5 and SNF6 genes. The snf7 mutation also behaved differently from mutations in SNF1 and SNF4 in that snf7 ssn6 double mutants displayed a synthetic phenotype of severe temperature sensitivity for growth. We also mapped SNF7 to the right arm of chromosome XII near the centromere.

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