SDC25, a dispensable Ras guanine nucleotide exchange factor of Saccharomyces cerevisiae differs from CDC25 by its regulation.

Boy‐Marcotte, Emmanuelle; Ikonomi, Pranvera; Jacquet, Michel

doi:10.1091/mbc.7.4.529

Cited by 50 publications

(43 citation statements)

References 45 publications

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“…Mechanism of Glucose Activation of Ras-Yeast Ras activation is controlled by the guanine nucleotide exchange proteins Cdc25 and Sdc25 of which the former plays a major role (29). We show that deletion of CDC25 severely delays the glucoseinduced increase in Ras2-GTP consistent with a requirement of Cdc25.…”

Section: Involvement Of Ras In Glucose-induced Camp Signaling-mentioning

confidence: 59%

Activation State of the Ras2 Protein and Glucose-induced Signaling in Saccharomyces cerevisiae

Colombo

Ronchetti

Thevelein

et al. 2004

Journal of Biological Chemistry

122

141

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The activity of adenylate cyclase in the yeast Saccharomyces cerevisiae is controlled by two G-protein systems, the Ras proteins and the G␣ protein Gpa2. Glucose activation of cAMP synthesis is thought to be mediated by Gpa2 and its G-protein-coupled receptor Gpr1. Using a sensitive GTP-loading assay for Ras2 we demonstrate that glucose addition also triggers a fast increase in the GTP loading state of Ras2 concomitant with the glucoseinduced increase in cAMP. This increase is severely delayed in a strain lacking Cdc25, the guanine nucleotide exchange factor for Ras proteins. Deletion of the RasGAPs IRA2 (alone or with IRA1) or the presence of RAS2 Val19 allele causes constitutively high Ras GTP loading that no longer increases upon glucose addition. The glucose-induced increase in Ras2 GTP-loading is not dependent on Gpr1 or Gpa2. Deletion of these proteins causes higher GTP loading indicating that the two G-protein systems might directly or indirectly interact. Because deletion of GPR1 or GPA2 reduces the glucoseinduced cAMP increase the observed enhancement of Ras2 GTP loading is not sufficient for full stimulation of cAMP synthesis. Glucose phosphorylation by glucokinase or the hexokinases is required for glucose-induced Ras2 GTP loading. These results indicate that glucose phosphorylation might sustain activation of cAMP synthesis by enhancing Ras2 GTP loading likely through inhibition of the Ira proteins. Strains with reduced feedback inhibition on cAMP synthesis also display elevated basal and induced Ras2 GTP loading consistent with the Ras2 protein acting as a target of the feedback-inhibition mechanism.In Saccharomyces cerevisiae the addition of glucose or other rapidly fermentable sugars to derepressed cells (carbonstarved or growing on a non-fermentable carbon source) triggers a remarkable variety of regulatory phenomena, including many rapid changes at the post-translational and transcriptional level. Several signaling pathways are activated by glucose. One of the best studied pathways is the cAMP/PKA 1 pathway. The main component of this signaling transduction pathway is adenylate cyclase, which catalyzes the synthesis of cAMP. In S. cerevisiae adenylate cyclase activity is controlled by the Ras proteins. These proteins are members of the small GTPase superfamily, which are active in the GTP-bound form and inactive in the GDP-bound form. Recently it has been demonstrated that in S. cerevisiae adenylate cyclase activity is also controlled by a heterotrimeric G␣-protein, Gpa2 (1). A G-protein-coupled receptor, Gpr1, has been identified to be responsible for activation of the Gpa2 protein (2-4). Two triggers are known to activate the cAMP/PKA pathway: the addition of glucose to derepressed cells and intracellular acidification. The Gpr1/Gpa2 G-protein-coupled receptor system is only required for glucose activation of cAMP synthesis (2, 5). The results reported in the literature about the role played by the Ras proteins in activation of cAMP synthesis are in part contradictory. Colombo et al. (5) show...

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Section: Involvement Of Ras In Glucose-induced Camp Signaling-mentioning

confidence: 59%

Activation State of the Ras2 Protein and Glucose-induced Signaling in Saccharomyces cerevisiae

Colombo

Ronchetti

Thevelein

et al. 2004

Journal of Biological Chemistry

122

141

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“…At least two factors with GEF activity toward Rab3A have already been described, (48), and it is possible that a similar situation may exist for other Rab proteins. Perhaps different proteins acting on Sec4p are differently regulated, with DSS4 only being essential under certain specialized conditions such as have been described for the Ras exchange factors encoded by the SCD25 and CDC25 genes (49).…”

Section: Discussionmentioning

confidence: 99%

Interactions of Nucleotide Release Factor Dss4p with Sec4p in the Post-Golgi Secretory Pathway of Yeast

Collins¹,

Brennwald²,

Garrett³

et al. 1997

Journal of Biological Chemistry

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SEC4 is an essential gene encoding a small GTPase that is involved in Golgi to cell surface transport in Saccharomyces cerevisiae and is a paradigm for studies on the mode of action of Rab proteins. We describe here the features of interaction of Sec4p with the accessory protein Dss4p. Dss4p is found both on membranes and in the cytosol; however, it is the membrane fraction that is complexed to Sec4p. Dss4p, like its mammalian counterpart, Mss4, binds zinc, and disruption of the zinc-binding site disrupts the ability of the protein to interact with Sec4p. DSS4 overexpression can rescue the lethal phenotype of two alleles of SEC4, corresponding to dominant mutations of Ras. We demonstrate that this suppression is due to the ability of Dss4p to form a tight complex with the mutant forms of Sec4p and hence sequester the mutant protein from its inhibitory effect. These results imply an in vivo role for Dss4p as a guanine nucleotide dissociation stimulator. In vitro the protein has the ability to stimulate the dissociation rate of both GDP and GTP from Sec4p. We examined the relationship of GDI1 and DSS4 with SEC4 both genetically and biochemically. These results exclude a role for DSS4 in the recruitment of Sec4p/GDI onto membranes.

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“…For the diauxic transition, yeast cells were grown in YNBS medium with 2 % glucose (Boy-Marcotte et al, 1996). Glucose concentration in the culture medium was monitored enzymically with glucose oxidase using Sigma Diagnostic Glucose reagent kit no 510-A.…”

Section: Plasmids and Strainsmentioning

confidence: 99%

“…RNA preparation and analysis. Total RNA extraction, gel electrophoresis of glyoxylated RNA and hybridization were performed as described earlier (Boy-Marcotte et al, 1996). Fifteen micrograms of total RNA per sample were fractionated on a 1 % agarose gel.…”

Section: Plasmids and Strainsmentioning

confidence: 99%

“…We have previously reported that Msn2p and\or Msn4p were essential for full induction of a set of genes that occurs at the diauxic transition, and that cAMP inhibited this transition (Boy-Marcotte et al, 1996). Therefore we looked at the phosphorylation state of Msn2p and Msn4p throughout the growth curve, in the presence and in the absence of cAMP (Fig.…”

Section: Camp Prevents Hyperphosphorylation Of Msn2p and Msn4p At Thementioning

confidence: 99%

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Hyperphosphorylation of Msn2p and Msn4p in response to heat shock and the diauxic shift is inhibited by cAMP in Saccharomyces cerevisiae

et al. 2000

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In response to various stresses, as well as during the diauxic transition, the Msn2p and Msn4p transcription factors of Saccharomyces cerevisiae are activated and induce a large set of genes. This activation is inhibited by the Ras/cAMP/PKA (cAMP-dependent protein kinase) pathway. Here we show by immunoblotting experiments that Msn2p and Msn4p are phosphorylated in vivo during growth on glucose, and become hyperphosphorylated at the diauxic transition and upon heat shock. This hyperphosphorylation is correlated with activation of Msn2/4p-dependent transcription. An increased level of cAMP prevents and reverses these hyperphosphorylations, indicating that kinases other than PKA are involved. These results suggest that PKA and stress-activated kinases control Msn2/4p activity by antagonistic phosphorylation. It was also noted that Msn4p is transiently increased at the diauxic transition. Msn2p and Msn4p present different hyperphosphorylation patterns in response to different stresses.

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SDC25, a dispensable Ras guanine nucleotide exchange factor of Saccharomyces cerevisiae differs from CDC25 by its regulation.

Abstract: The SDC25 gene of Saccharomyces cerevisiae is homologous to CDC25. Its 3' domain encodes a guanine nucleotide exchange factor (GEF)

Cited by 50 publications

References 45 publications

Activation State of the Ras2 Protein and Glucose-induced Signaling in Saccharomyces cerevisiae

Activation State of the Ras2 Protein and Glucose-induced Signaling in Saccharomyces cerevisiae

Interactions of Nucleotide Release Factor Dss4p with Sec4p in the Post-Golgi Secretory Pathway of Yeast

Hyperphosphorylation of Msn2p and Msn4p in response to heat shock and the diauxic shift is inhibited by cAMP in Saccharomyces cerevisiae

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