scholarly journals Glycolysis Controls Plasma Membrane Glucose Sensors To Promote Glucose Signaling in Yeasts

2014 ◽  
Vol 35 (4) ◽  
pp. 747-757 ◽  
Author(s):  
Amélie Cairey-Remonnay ◽  
Julien Deffaud ◽  
Micheline Wésolowski-Louvel ◽  
Marc Lemaire ◽  
Alexandre Soulard
Keyword(s):  
Signaling Pathway ◽  
Glucose Sensor ◽  
Kluyveromyces Lactis ◽  
Glucose Sensors ◽  
Content Type ◽  
Glucose Signaling ◽  
Extracellular Glucose ◽  
Glucose Accumulation ◽  
The Stability ◽  
Intracellular Glucose

Sensing of extracellular glucose is necessary for cells to adapt to glucose variation in their environment. In the respiratory yeastKluyveromyces lactis, extracellular glucose controls the expression of major glucose permease geneRAG1through a cascade similar to theSaccharomyces cerevisiaeSnf3/Rgt2/Rgt1 glucose signaling pathway. This regulation depends also on intracellular glucose metabolism since we previously showed that glucose induction of theRAG1gene is abolished in glycolytic mutants. Here we show that glycolysis regulatesRAG1expression through theK. lactisRgt1 (KlRgt1) glucose signaling pathway by targeting the localization and probably the stability of Rag4, the single Snf3/Rgt2-type glucose sensor ofK. lactis. Additionally, the control exerted by glycolysis on glucose signaling seems to be conserved inS. cerevisiae. This retrocontrol might prevent yeasts from unnecessary glucose transport and intracellular glucose accumulation.

scholarly journals The SWI/SNF KlSnf2 Subunit Controls the Glucose Signaling Pathway To Coordinate Glycolysis and Glucose Transport in Kluyveromyces lactis

2012 ◽  
Vol 11 (11) ◽  
pp. 1382-1390 ◽  
Author(s):  
Pascale Cotton ◽  
Alexandre Soulard ◽  
Micheline Wésolowski-Louvel ◽  
Marc Lemaire
Keyword(s):  
Signaling Pathway ◽  
Glucose Transport ◽  
Chromatin Remodeling ◽  
Kluyveromyces Lactis ◽  
Content Type ◽  
Glucose Signaling ◽  
Helix Loop Helix ◽  
Reverse Transcription Quantitative Pcr ◽  
Extracellular Glucose ◽  
Transcriptional Effect

ABSTRACTInKluyveromyces lactis, the expression of the major glucose permease geneRAG1is controlled by extracellular glucose through a signaling cascade similar to theSaccharomyces cerevisiaeSnf3/Rgt2/Rgt1 pathway. We have identified a key component of theK. lactisglucose signaling pathway by characterizing a new mutation,rag20-1, which impairs the regulation ofRAG1and hexokinaseRAG5genes by glucose. Functional complementation of therag20-1mutation identified theKlSNF2gene, which encodes a protein 59% identical toS. cerevisiaeSnf2, the major subunit of the SWI/SNF chromatin remodeling complex. Reverse transcription-quantitative PCR and chromatin immunoprecipitation analyses confirmed that the KlSnf2 protein binds toRAG1andRAG5promoters and promotes the recruitment of the basic helix-loop-helix Sck1 activator. Besides this transcriptional effect, KlSnf2 is also implicated in the glucose signaling pathway by controlling Sms1 and KlRgt1 posttranscriptional modifications. When KlSnf2 is absent, Sms1 is not degraded in the presence of glucose, leading to constitutiveRAG1gene repression by KlRgt1. Our work points out the crucial role played by KlSnf2 in the regulation of glucose transport and metabolism inK. lactis, notably, by suggesting a link between chromatin remodeling and the glucose signaling pathway.

scholarly journals Characterization of KlGRR1 and SMS1 Genes, Two New Elements of the Glucose Signaling Pathway of Kluyveromyces lactis

2008 ◽  
Vol 7 (8) ◽  
pp. 1299-1308 ◽  
Author(s):  
Martina Hnatova ◽  
Micheline Wésolowski-Louvel ◽  
Guenaëlle Dieppois ◽  
Julien Deffaud ◽  
Marc Lemaire
Keyword(s):  
Signaling Pathway ◽  
Glucose Transporter ◽  
Glucose Sensor ◽  
Kluyveromyces Lactis ◽  
Single Gene ◽  
Negative Regulator ◽  
Casein Kinase I ◽  
Glucose Signaling ◽  
F Box Protein

ABSTRACT The expression of the major glucose transporter gene, RAG1, is induced by glucose in Kluyveromyces lactis. This regulation involves several pathways, including one that is similar to Snf3/Rgt2-ScRgt1 in Saccharomyces cerevisiae. We have identified missing key components of the K. lactis glucose signaling pathway by comparison to the same pathway of S. cerevisiae. We characterized a new mutation, rag19, which impairs RAG1 regulation. The Rag19 protein is 43% identical to the F-box protein ScGrr1 of S. cerevisiae and is able to complement an Scgrr1 mutation. In the K. lactis genome, we identified a single gene, SMS1 (for similar to Mth1 and Std1), that encodes a protein showing an average of 50% identity with Mth1 and Std1, regulators of the ScRgt1 repressor. The suppression of the rag4 (glucose sensor), rag8 (casein kinase I), and rag19 mutations by the Δsms1 deletion, together with the restoration of RAG1 transcription in the double mutants, demonstrates that Sms1 is a negative regulator of RAG1 expression and is acting downstream of Rag4, Rag8, and Rag19 in the cascade. We report that Sms1 regulates KlRgt1 repressor activity by preventing its phosphorylation in the absence of glucose, and that SMS1 is regulated by glucose, both at the transcriptional and the posttranslational level. Two-hybrid interactions of Sms1 with the glucose sensor and KlRgt1 repressor suggest that Sms1 mediates the glucose signal from the plasma membrane to the nucleus. All of these data demonstrated that Sms1 was the K. lactis homolog of MTH1 and STD1 of S. cerevisiae. Interestingly, MTH1 and STD1 were unable to complement a Δsms1 mutation.

scholarly journals A novel role for yeast casein kinases in glucose sensing and signaling

2016 ◽  
Vol 27 (21) ◽  
pp. 3369-3375 ◽  
Author(s):  
Chris Snowdon ◽  
Mark Johnston
Keyword(s):  
Glucose Sensor ◽  
Glucose Sensing ◽  
Glucose Sensors ◽  
Dependent Manner ◽  
Glucose Signaling ◽  
Cytoplasmic Tails ◽  
Extracellular Glucose ◽  
Casein Kinases ◽  
Intracellular Signal ◽  
A Site

Yeasts have sophisticated signaling pathways for sensing glucose, their preferred carbon source, to regulate its uptake and metabolism. One of these is the sensor/receptor-repressor (SRR) pathway, which detects extracellular glucose and transmits an intracellular signal that induces expression of HXT genes. The yeast casein kinases (Ycks) are key players in this pathway. Our model of the SRR pathway had the Ycks functioning downstream of the glucose sensors, transmitting the signal from the sensors to the Mth1 and Std1 corepressors that are required for repression of HXT gene expression. However, we found that overexpression of Yck1 fails to restore glucose signaling in a glucose sensor mutant. Conversely, overexpression of a glucose sensor suppresses the signaling defect of a yck mutant. These results suggest that the Ycks act upstream or at the level of the glucose sensors. Indeed, we found that the glucose sensor Rgt2 is phosphorylated on Yck consensus sites in its C-terminal tail in a Yck-dependent manner and that this phosphorylation is required for corepressor binding and ultimately HXT expression. This leads to a revised model of the SRR pathway in which the Ycks prime a site on the cytoplasmic tails of the glucose sensors to promote binding of the corepressors.

scholarly journals Rgt1p of Saccharomyces cerevisiae, a key regulator of glucose-induced genes, is both an activator and a repressor of transcription.

1996 ◽  
Vol 16 (11) ◽  
pp. 6419-6426 ◽  
Author(s):  
S Ozcan ◽  
T Leong ◽  
M Johnston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Glucose Transporter ◽  
Glucose Sensor ◽  
Glucose Sensors ◽  
Hexose Transporter ◽  
Glucose Signaling ◽  
Low Glucose ◽  
Induced Genes ◽  
Low Levels ◽  
High Concentrations

The RGT1 gene of Saccharomyces cerevisiae plays a central role in the glucose-induced expression of hexose transporter (HXT) genes. Genetic evidence suggests that it encodes a repressor of the HXT genes whose function is inhibited by glucose. Here, we report the isolation of RGT1 and demonstrate that it encodes a bifunctional transcription factor. Rgt1p displays three different transcriptional modes in response to glucose: (i) in the absence of glucose, it functions as a transcriptional repressor; (ii) high concentrations of glucose cause it to function as a transcriptional activator; and (iii) in cells growing on low levels of glucose, Rgt1p has a neutral role, neither repressing nor activating transcription. Glucose alters Rgt1p function through a pathway that includes two glucose sensors, Snf3p and Rgt2p, and Grr1p. The glucose transporter Snf3p, which appears to be a low-glucose sensor, is required for inhibition of Rgt1p repressor function by low levels of glucose. Rgt2p, a glucose transporter that functions as a high-glucose sensor, is required for conversion of Rgt1p into an activator by high levels of glucose. Grr1p, a component of the glucose signaling pathway, is required both for inactivation of Rgt1p repressor function by low levels of glucose and for conversion of Rgt1p into an activator at high levels of glucose. Thus, signals generated by two different glucose sensors act through Grr1p to determine Rgt1p function.

scholarly journals Sck1 Negatively Regulates Gpa2-Mediated Glucose Signaling in Schizosaccharomyces pombe

2013 ◽  
Vol 13 (2) ◽  
pp. 202-208 ◽  
Author(s):  
Dayna K. Mudge ◽  
Fan Yang ◽  
Brian M. Currie ◽  
James M. Kim ◽  
Kelly Yeda ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Schizosaccharomyces Pombe ◽  
G Protein ◽  
Free Form ◽  
Slight Reduction ◽  
Content Type ◽  
Glucose Signaling ◽  
Extracellular Glucose ◽  
The One ◽  
Two Hybrid

ABSTRACTSchizosaccharomyces pombedetects extracellular glucose via a G protein-mediated cyclic AMP (cAMP)-signaling pathway activating protein kinase A (PKA) and regulating transcription of genes involved in metabolism and sexual development. In this pathway, Gpa2 Gα binds to and activates adenylyl cyclase in response to glucose detection by the Git3 G protein-coupled receptor. Using a two-hybrid screen to identify extrinsic regulators of Gpa2, we isolated a clone that expresses codons 471 to 696 of the Sck1 kinase, which appears to display a higher affinity for Gpa2K270E-activated Gα relative to Gpa2+Gα. Deletion ofsck1+or mutational inactivation of the Sck1 kinase produces phenotypes reflecting increased PKA activity in strains expressing Gpa2+or Gpa2K270E, suggesting that Sck1 negatively regulates PKA activation through Gpa2. In contrast to the Gpa2K270EGDP-GTP exchange rate mutant, GTPase-defective Gpa2R176Hweakly binds Sck1 in the two-hybrid screen and a deletion ofsck1+in a Gpa2R176Hstrain confers phenotypes consistent with a slight reduction in PKA activity. Finally, deletingsck1+in agpa2Δ strain results in phenotypes consistent with a second role for Sck1 acting in parallel with PKA. In addition to this parallel role with PKA, our data suggest that Sck1 negatively regulates Gpa2, possibly targeting the nucleotide-free form of the protein that may expose the one and only AKT/PKB consensus site in Gpa2 for Sck1 to bind. This dual role for Sck1 may allowS. pombeto produce distinct biological responses to glucose and nitrogen starvation signals that both activate the Wis1-Spc1/StyI stress-activated protein kinase (SAPK) pathway.

scholarly journals The Rag4 Glucose Sensor Is Involved in the Hypoxic Induction ofKlPDC1Gene Expression in the Yeast Kluyveromyces lactis

2010 ◽  
Vol 10 (1) ◽  
pp. 146-148 ◽  
Author(s):  
C. Micolonghi ◽  
M. Wésolowski-Louvel ◽  
M. M. Bianchi
Keyword(s):  
Glucose Sensor ◽  
Oxygen Sensing ◽  
Kluyveromyces Lactis ◽  
Content Type ◽  
Hypoxic Induction ◽  
Regulation Of Metabolism

ABSTRACTKluyveromyces lactisis a yeast which cannot grow under strict anaerobiosis. To date, no factors responsible for oxygen sensing and oxygen-dependent regulation of metabolism have been identified. In this paper we present the identification of the glucose sensor Rag4 as a factor essential for oxygen-dependent regulation of the fermentative pathway.

scholarly journals The glucose metabolite methylglyoxal inhibits expression of the glucose transporter genes by inactivating the cell surface glucose sensors Rgt2 and Snf3 in yeast

2016 ◽  
Vol 27 (5) ◽  
pp. 862-871 ◽  
Author(s):  
Adhiraj Roy ◽  
Salman Hashmi ◽  
Zerui Li ◽  
Angela D. Dement ◽  
Kyu Hong Cho ◽  
...  
Keyword(s):  
Cell Surface ◽  
Glucose Transporter ◽  
Inhibitory Effect ◽  
Glucose Sensors ◽  
Yeast Cells ◽  
Yeast Cell Surface ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Extracellular Glucose ◽  
The Stability

Methylglyoxal (MG) is a cytotoxic by-product of glycolysis. MG has inhibitory effect on the growth of cells ranging from microorganisms to higher eukaryotes, but its molecular targets are largely unknown. The yeast cell-surface glucose sensors Rgt2 and Snf3 function as glucose receptors that sense extracellular glucose and generate a signal for induction of expression of genes encoding glucose transporters ( HXTs). Here we provide evidence that these glucose sensors are primary targets of MG in yeast. MG inhibits the growth of glucose-fermenting yeast cells by inducing endocytosis and degradation of the glucose sensors. However, the glucose sensors with mutations at their putative ubiquitin-acceptor lysine residues are resistant to MG-induced degradation. These results suggest that the glucose sensors are inactivated through ubiquitin-mediated endocytosis and degraded in the presence of MG. In addition, the inhibitory effect of MG on the glucose sensors is greatly enhanced in cells lacking Glo1, a key component of the MG detoxification system. Thus the stability of these glucose sensors seems to be critically regulated by intracellular MG levels. Taken together, these findings suggest that MG attenuates glycolysis by promoting degradation of the cell-surface glucose sensors and thus identify MG as a potential glycolytic inhibitor.

Low-voltage field-emission SEM of polymeric membranes for glucose biosensors

1990 ◽  
Vol 48 (3) ◽  
pp. 860-861
Author(s):  
Lorna K. Mayo ◽  
Kenneth C. Moore ◽  
Mark A. Arnold
Keyword(s):  
Glucose Sensor ◽  
Low Voltage ◽  
Glucose Sensors ◽  
Polymeric Membranes ◽  
Artificial Endocrine Pancreas ◽  
Self Monitoring ◽  
Conducting Materials ◽  
Insulin Dependent ◽  
Living Tissues ◽  
Voltage Scanning

An implantable artificial endocrine pancreas consisting of a glucose sensor and a closed-loop insulin delivery system could potentially replace the need for glucose self-monitoring and regulation among insulin dependent diabetics. Achieving such a break through largely depends on the development of an appropriate, biocompatible membrane for the sensor. Biocompatibility is crucial since changes in the glucose sensors membrane resulting from attack by orinter action with living tissues can interfere with sensor reliability and accuracy. If such interactions can be understood, however, compensations can be made for their effects. Current polymer technology offers several possible membranes that meet the unique chemical dynamics required of a glucose sensor. Two of the most promising polymer membranes are polytetrafluoroethylene (PTFE) and silicone (Si). Low-voltage scanning electron microscopy, which is an excellent technique for characterizing a variety of polymeric and non-conducting materials, 27 was applied to the examination of experimental sensor membranes.

scholarly journals Site-Directed Mutagenesis of the Heterotrimeric Killer Toxin Zymocin Identifies Residues Required for Early Steps in Toxin Action

2014 ◽  
Vol 80 (20) ◽  
pp. 6549-6559 ◽  
Author(s):  
Sabrina Wemhoff ◽  
Roland Klassen ◽  
Friedhelm Meinhardt
Keyword(s):  
Kluyveromyces Lactis ◽  
Killer Toxin ◽  
Cysteine Residue ◽  
Site Directed Mutagenesis ◽  
Target Cells ◽  
Directed Mutagenesis ◽  
Content Type ◽  
Protein Toxin ◽  
Assisted Delivery

ABSTRACTZymocin is aKluyveromyces lactisprotein toxin composed of αβγ subunits encoded by the cytoplasmic virus-like element k1 and functions by αβ-assisted delivery of the anticodon nuclease (ACNase) γ into target cells. The toxin binds to cells' chitin and exhibits chitinase activityin vitrothat might be important during γ import.Saccharomyces cerevisiaestrains carrying k1-derived hybrid elements deficient in either αβ (k1ORF2) or γ (k1ORF4) were generated. Loss of either gene abrogates toxicity, and unexpectedly, Orf2 secretion depends on Orf4 cosecretion. Functional zymocin assembly can be restored by nuclear expression of k1ORF2 or k1ORF4, providing an opportunity to conduct site-directed mutagenesis of holozymocin. Complementation required active site residues of α's chitinase domain and the sole cysteine residue of β (Cys250). Since βγ are reportedly disulfide linked, the requirement for the conserved γ C231 was probed. Toxicity of intracellularly expressed γ C231A indicated no major defect in ACNase activity, while complementation of k1ΔORF4 by γ C231A was lost, consistent with a role of β C250 and γ C231 in zymocin assembly. To test the capability of αβ to carry alternative cargos, the heterologous ACNase fromPichia acaciae(P. acaciaeOrf2 [PaOrf2]) was expressed, along with its immunity gene, in k1ΔORF4. While efficient secretion of PaOrf2 was detected, suppression of the k1ΔORF4-derived k1Orf2 secretion defect was not observed. Thus, the dependency of k1Orf2 on k1Orf4 cosecretion needs to be overcome prior to studying αβ's capability to deliver other cargo proteins into target cells.

scholarly journals Streptomycin-Induced Expression in Bacillus subtilis of YtnP, a Lactonase-Homologous Protein That Inhibits Development and Streptomycin Production in Streptomyces griseus

2011 ◽  
Vol 78 (2) ◽  
pp. 599-603 ◽  
Author(s):  
Johannes Schneider ◽  
Ana Yepes ◽  
Juan C. Garcia-Betancur ◽  
Isa Westedt ◽  
Benjamin Mielich ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Signaling Pathway ◽  
Streptomyces Griseus ◽  
Aerial Mycelium ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Induced Expression ◽  
Content Type ◽  
Homologous Protein

ABSTRACTBacillus subtilisinduces expression of the geneytnPin the presence of the antimicrobial streptomycin, produced by the Gram-positive bacteriumStreptomyces griseus.ytnPencodes a lactonase-homologous protein that is able to inhibit the signaling pathway required for the streptomycin production and development of aerial mycelium inS. griseus.

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