Regulation of phosphoenolpyruvate carboxykinase and pyruvate kinase in Saccharomyces cerevisiae grown in the presence of glycolytic and gluconeogenic carbon sources and the role of mitochondrial function on gluconeogenesis

1986 ◽  
Vol 32 (12) ◽  
pp. 969-972 ◽  
Author(s):  
Albert J. Wilson ◽  
J. K. Bhattacharjee
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pyruvate Kinase ◽  
Growth Medium ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Carbon Sources ◽  
Absolute Requirement ◽  
Fructose 1,6 Bisphosphatase ◽  
Futile Cycling ◽  
Respiratory Deficient

Phosphoenolpyruvate carboxykinase (PEPCKase) and pyruvate kinase (PKase) were measured in Saccharomyces cerevisiae grown in the presence of glycolytic and gluconeogenic carbon sources. The PEPCKase activity was highest in ethanol-grown cells. However, high PEPCKase activity was also observed in cells grown in 1% glucose, especially as compared with the activity of sucrose-, maltose-, or galactose-grown cells. Activity was first detected after 12 h when glucose was exhausted from the growth medium. The PKase activity was very high in glucose-grown cells; considerable activity was also present in ethanol- and pyruvate-grown cells. The absolute requirement of respiration for gluconeogenesis was demonstrated by the absence or significantly low levels of PEPCKase and fructose-1,6-bisphosphatase activities observed in respiratory deficient mutants, as well as in wild-type S. cerevisiae cells grown in the presence of glucose and antimycin A or chloramphenicol. Obligate glycolytic and gluconeogenic enzymes were present sumultaneously only in stationary phase cells, but not in exponential phase cells; hence futile cycling could not occur in log phase cells regardless of the presence of carbon source in the growth medium.

Fatty acylation is important but not essential for Saccharomyces cerevisiae RAS function

1987 ◽  
Vol 7 (7) ◽  
pp. 2344-2351
Author(s):  
R J Deschenes ◽  
J R Broach
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Function ◽  
Membrane Fraction ◽  
Carbon Sources ◽  
Fatty Acyl ◽  
Yeast Saccharomyces Cerevisiae ◽  
Fatty Acyl Moiety ◽  
Fatty Acylation ◽  
Absolute Requirement

Two proteins in the yeast Saccharomyces cerevisiae that are encoded by the genes RAS1 and RAS2 are structurally and functionally homologous to proteins of the mammalian ras oncogene family. We examined the role of fatty acylation in the maturation of yeast RAS2 protein by creating mutants in the putative palmitate addition site located at the carboxyl terminus of the protein. Two mutations, Cys-318 to an opal termination codon and Cys-319 to Ser-319, were created in vitro and substituted in the chromosome in place of the normal RAS2 allele. These changes resulted in a failure of RAS2 protein to be acylated with palmitate and a failure of RAS2 protein to be localized to a membrane fraction. The mutations yielded a Ras2- phenotype with respect to the ability of the resultant mutants to grow on nonfermentable carbon sources and to complement ras1- mutants. However, overexpression of the ras2Ser-319 product yielded a Ras+ phenotype without a corresponding association of the mutant protein with the membrane fraction. We conclude that the presence of a fatty acyl moiety is important for localizing RAS2 protein to the membrane where it is active but that the fatty acyl group is not an absolute requirement of RAS2 protein function.

scholarly journals The Gluconeogenic Enzyme Fructose-1,6-Bisphosphatase Is Dispensable for Growth of the Yeast Yarrowia lipolytica in Gluconeogenic Substrates

2008 ◽  
Vol 7 (10) ◽  
pp. 1742-1749 ◽  
Author(s):  
Raquel Jardón ◽  
Carlos Gancedo ◽  
Carmen-Lisset Flores
Keyword(s):  
Yarrowia Lipolytica ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Isocitrate Lyase ◽  
Carbon Sources ◽  
Subcellular Fractionation ◽  
Fructose 1,6 Bisphosphatase ◽  
Genes Encoding ◽  
Key Enzyme ◽  
Gluconeogenic Enzyme ◽  
Fructose 1,6 Bisphosphate

ABSTRACT The genes encoding gluconeogenic enzymes in the nonconventional yeast Yarrowia lipolytica were found to be differentially regulated. The expression of Y. lipolytica FBP1 (YlFBP1) encoding the key enzyme fructose-1,6-bisphosphatase was not repressed by glucose in contrast with the situation in other yeasts; however, this sugar markedly repressed the expression of YlPCK1, encoding phosphoenolpyruvate carboxykinase, and YlICL1, encoding isocitrate lyase. We constructed Y. lipolytica strains with two different disrupted versions of YlFBP1 and found that they grew much slower than the wild type in gluconeogenic carbon sources but that growth was not abolished as happens in most microorganisms. We attribute this growth to the existence of an alternative phosphatase with a high Km (2.3 mM) for fructose-1,6-bisphosphate. The gene YlFBP1 restored fructose-1,6-bisphosphatase activity and growth in gluconeogenic carbon sources to a Saccharomyces cerevisiae fbp1 mutant, but the introduction of the FBP1 gene from S. cerevisiae in the Ylfbp1 mutant did not produce fructose-1,6-bisphosphatase activity or growth complementation. Subcellular fractionation revealed the presence of fructose-1,6-bisphosphatase both in the cytoplasm and in the nucleus.

scholarly journals Interaction of the Srb10 Kinase with Sip4, a Transcriptional Activator of Gluconeogenic Genes in Saccharomyces cerevisiae

2001 ◽  
Vol 21 (17) ◽  
pp. 5790-5796 ◽  
Author(s):  
Olivier Vincent ◽  
Sergei Kuchin ◽  
Seung-Pyo Hong ◽  
Robert Townley ◽  
Valmik K. Vyas ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase Ii ◽  
Transcriptional Repression ◽  
Transcriptional Control ◽  
Carbon Sources ◽  
Transcriptional Activator ◽  
Glucose Limitation ◽  
Cell Extracts ◽  
Rna Polymerase Ii Holoenzyme

ABSTRACT Sip4 is a Zn2Cys6 transcriptional activator that binds to the carbon source-responsive elements of gluconeogenic genes in Saccharomyces cerevisiae. The Snf1 protein kinase interacts with Sip4 and regulates its phosphorylation and activator function in response to glucose limitation; however, evidence suggested that another kinase also regulates Sip4. Here we examine the role of the Srb10 kinase, a component of the RNA polymerase II holoenzyme that has been primarily implicated in transcriptional repression but also positively regulates Gal4. We show that Srb10 is required for phosphorylation of Sip4 during growth in nonfermentable carbon sources and that the catalytic activity of Srb10 stimulates the ability of LexA-Sip4 to activate transcription of a reporter. Srb10 and Sip4 coimmunoprecipitate from cell extracts and interact in two-hybrid assays, suggesting that Srb10 regulates Sip4 directly. We also present evidence that the Srb10 and Snf1 kinases interact with different regions of Sip4. These findings support the view that the Srb10 kinase not only plays negative roles in transcriptional control but also has broad positive roles during growth in carbon sources other than glucose.

scholarly journals Vid24p, a Novel Protein Localized to the Fructose-1,6-bisphosphatase–containing Vesicles, Regulates Targeting of Fructose-1,6-bisphosphatase from the Vesicles to the Vacuole for Degradation

1998 ◽  
Vol 140 (6) ◽  
pp. 1347-1356 ◽  
Author(s):  
Meng-Chieh Chiang ◽  
Hui-Ling Chiang
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Membrane Protein ◽  
Critical Role ◽  
Carbon Sources ◽  
Degradation Pathway ◽  
Yeast Cells ◽  
Fructose 1,6 Bisphosphatase ◽  
Peripheral Membrane Protein ◽  
Gluconeogenic Enzyme ◽  
Novel Protein

Glucose regulates the degradation of the key gluconeogenic enzyme, fructose-1,6-bisphosphatase (FBPase), in Saccharomyces cerevisiae. FBPase is targeted from the cytosol to a novel type of vesicle, and then to the vacuole for degradation when yeast cells are transferred from medium containing poor carbon sources to fresh glucose. To identify proteins involved in the FBPase degradation pathway, we cloned our first VID (vacuolar import and degradation) gene. The VID24 gene was identified by complementation of the FBPase degradation defect of the vid24-1 mutant. Vid24p is a novel protein of 41 kD and is synthesized in response to glucose. Vid24p is localized to the FBPase-containing vesicles as a peripheral membrane protein. In the absence of functional Vid24p, FBPase accumulates in the vesicles and fails to move to the vacuole, suggesting that Vid24p regulates FBPase targeting from the vesicles to the vacuole. FBPase sequestration into the vesicles is not affected in the vid24-1 mutant, indicating that Vid24p acts after FBPase sequestration into the vesicles has occurred. Vid24p is the first protein identified that marks the FBPase-containing vesicles and plays a critical role in delivering FBPase from the vesicles to the vacuole for degradation.

scholarly journals Saccharomyces cerevisiae Multidrug Resistance Transporter Qdr2 Is Implicated in Potassium Uptake, Providing a Physiological Advantage to Quinidine-Stressed Cells

2006 ◽  
Vol 6 (2) ◽  
pp. 134-142 ◽  
Author(s):  
Rita C. Vargas ◽  
Raúl García-Salcedo ◽  
Sandra Tenreiro ◽  
Miguel C. Teixeira ◽  
Alexandra R. Fernandes ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Yeast Cell ◽  
Experimental Evidence ◽  
Growth Medium ◽  
Auxotrophic Strain ◽  
General Amino Acid Control ◽  
Stressed Cells ◽  
Multidrug Resistance Transporter

ABSTRACT The QDR2 gene of Saccharomyces cerevisiae encodes a putative plasma membrane drug:H+ antiporter that confers resistance against quinidine, barban, bleomycin, and cisplatin. This work provides experimental evidence of defective K+ (Rb+) uptake in the absence of QDR2. The direct involvement of Qdr2p in K+ uptake is reinforced by the fact that increased K+ (Rb+) uptake due to QDR2 expression is independent of the Trk1p/Trk2p system. QDR2 expression confers a physiological advantage for the yeast cell during the onset of K+ limited growth, due either to a limiting level of K+ in the growth medium or to the presence of quinidine. This drug decreases the K+ uptake rate and K+ accumulation in the yeast cell, especially in the Δqdr2 mutant. Qdr2p also helps to sustain the decrease of intracellular pH in quinidine-stressed cells in growth medium at pH 5.5 by indirectly promoting H+ extrusion affected by the drug. The results are consistent with the hypothesis that Qdr2p may also couple K+ movement with substrate export, presumably with quinidine. Other clues to the biological role of QDR2 in the yeast cell come from two additional lines of experimental evidence. First, QDR2 transcription is activated under nitrogen (NH4 +) limitation or when the auxotrophic strain examined enters stationary phase due to leucine limitation, this regulation being dependent on general amino acid control by Gcn4p. Second, the amino acid pool is higher in Δqdr2 cells than in wild-type cells, indicating that QDR2 expression is, directly or indirectly, involved in amino acid homeostasis.

scholarly journals Physiological concentrations of 2-oxoglutarate regulate the activity of phosphoenolpyruvate carboxykinase in liver

1992 ◽  
Vol 285 (3) ◽  
pp. 767-771 ◽  
Author(s):  
M A Titheradge ◽  
R A Picking ◽  
R C Haynes
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Rat Hepatocytes ◽  
Fasted State ◽  
Stimulation Of

2-Oxoglutarate was found to inhibit purified rat liver phosphoenolpyruvate carboxykinase when the assay was performed in the direction of either phosphoenolpyruvate or oxaloacetate synthesis. The inhibition was competitive with respect to oxaloacetate or phosphoenolpyruvate, the Ki values being 0.32 +/- 0.04 mM 0.63 +/- 0.19 mM respectively. 2-Oxoglutarate inhibited non-competitively when tested against GTP or Mn2+. The reported cytosolic concentrations of 2-oxoglutarate in rat hepatocytes are such that the enzyme is likely to be significantly inhibited under basal conditions. The cytosolic concentration of 2-oxoglutarate is known to fall precipitously under the influence of glucagon and other hormones that stimulate gluconeogenesis, and it is suggested that the hormone-induced decrease in 2-oxoglutarate content would alleviate the inhibition of phosphoenolpyruvate carboxykinase and stimulate flux from oxaloacetate to phosphoenolpyruvate. The implications of this finding to the rationalization of the role of pyruvate kinase in the stimulation of gluconeogenesis in the fasted state are discussed.

scholarly journals The yeast Mig1 transcriptional repressor is dephosphorylated by glucose-dependent and independent mechanisms

2017 ◽  
Author(s):  
Sviatlana Shashkova ◽  
Adam J.M. Wollman ◽  
Mark C. Leake ◽  
Stefan Hohmann
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Tyrosine Phosphorylation ◽  
Growth Medium ◽  
Carbon Sources ◽  
Transcriptional Repressor ◽  
Altered Glucose ◽  
Complex Manner ◽  
Dependent Mechanism

AbstractSaccharomyces cerevisiae AMPK/Snf1 regulates glucose derepression of genes required for utilization of alternative carbon sources through the transcriptional repressor Mig1. It has been suggested that the Glc7-Reg1 phosphatase dephosphorylates Mig1. Here we report that Mig1 is dephosphorylated by Glc7-Reg1 in an apparently glucose-dependent mechanism but also by a mechanism independent of glucose and Glc7-Reg1. In addition to serine/threonine phosphatases another process including tyrosine phosphorylation seems crucial for Mig1 regulation. Taken together, Mig1 dephosphorylation appears to be controlled in a complex manner, in line with the importance for rapid and sensitive regulation upon altered glucose concentrations in the growth medium.

scholarly journals Metabolic control of hepatic gluconeogenesis during exercise

1983 ◽  
Vol 212 (3) ◽  
pp. 633-639 ◽  
Author(s):  
G L Dohm ◽  
E A Newsholme
Keyword(s):  
Metabolic Control ◽  
Pyruvate Kinase ◽  
Pyruvate Carboxylase ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Prolonged Exercise ◽  
Allosteric Effectors ◽  
Fructose 1,6 Bisphosphatase ◽  
Metabolite Concentrations ◽  
Fructose 1,6 Bisphosphate ◽  
Hexose Phosphates

Prolonged exercise increased the concentrations of the hexose phosphates and phosphoenolpyruvate and depressed those of fructose 1,6-bisphosphate, triose phosphates and pyruvate in the liver of the rat. Since exercise increases gluconeogenic flux, these changes in metabolite concentrations suggest that metabolic control is exerted, at least, at the fructose 6-phosphate/fructose 1,6-bisphosphate and phosphoenolpyruvate/pyruvate substrate cycles. Exercise increased the maximal activities of glucose 6-phosphatase, fructose 1,6-bisphosphatase, pyruvate kinase and pyruvate carboxylase in the liver, but there were no changes in those of glucokinase, 6-phosphofructokinase and phosphoenolpyruvate carboxykinase. Exercise changed the concentrations of several allosteric effectors of the glycolytic or gluconeogenic enzymes in liver; the concentrations of acetyl-CoA, ADP and AMP were increased, whereas those of ATP, fructose 1,6-bisphosphate and fructose 2,6-bisphosphate were decreased. The effect of exercise on the phosphorylation-dephosphorylation state of pyruvate kinase was investigated by measuring the activities under conditions of saturating and subsaturating concentrations of substrate. The submaximal activity of pyruvate kinase (0.5 mM-phosphoenolpyruvate), expressed as percentage of Vmax., decreased in the exercised animals to less than half that found in the controls. These changes suggest that hepatic pyruvate kinase is less active during exercise, possibly owing to phosphorylation of the enzyme, and this may play a role in increasing the rate of gluconeogenesis.

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