1
|
Botman D, Kanagasabapathi S, Rep MI, van Rossum K, Tutucci E, Teusink B. cAMP in budding yeast: Also a messenger for sucrose metabolism? BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119706. [PMID: 38521467 DOI: 10.1016/j.bbamcr.2024.119706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 02/28/2024] [Accepted: 03/04/2024] [Indexed: 03/25/2024]
Abstract
S. cerevisiae (or budding yeast) is an important micro-organism for sucrose-based fermentation in biotechnology. Yet, it is largely unknown how budding yeast adapts to sucrose transitions. Sucrose can only be metabolized when the invertase or the maltose machinery are expressed and we propose that the Gpr1p receptor signals extracellular sucrose availability via the cAMP peak to adapt cells accordingly. A transition to sucrose or glucose gave a transient cAMP peak which was maximally induced for sucrose. When transitioned to sucrose, cAMP signalling mutants showed an impaired cAMP peak together with a lower growth rate, a longer lag phase and a higher final OD600 compared to a glucose transition. These effects were not caused by altered activity or expression of enzymes involved in sucrose metabolism and imply a more general metabolic adaptation defect. Basal cAMP levels were comparable among the mutant strains, suggesting that the transient cAMP peak is required to adapt cells correctly to sucrose. We propose that the short-term dynamics of the cAMP signalling cascade detects long-term extracellular sucrose availability and speculate that its function is to maintain a fermentative phenotype at continuously low glucose and fructose concentrations.
Collapse
Affiliation(s)
- Dennis Botman
- Systems Biology Lab, AIMMS/ALIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, the Netherlands.
| | - Sineka Kanagasabapathi
- Systems Biology Lab, AIMMS/ALIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, the Netherlands
| | - Mila I Rep
- Systems Biology Lab, AIMMS/ALIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, the Netherlands
| | - Kelly van Rossum
- Systems Biology Lab, AIMMS/ALIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, the Netherlands
| | - Evelina Tutucci
- Systems Biology Lab, AIMMS/ALIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, the Netherlands
| | - Bas Teusink
- Systems Biology Lab, AIMMS/ALIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, the Netherlands.
| |
Collapse
|
2
|
Botman D, Kanagasabapathi S, Savakis P, Teusink B. Using the AKAR3-EV biosensor to assess Sch9p- and PKA-signalling in budding yeast. FEMS Yeast Res 2023; 23:foad029. [PMID: 37173282 PMCID: PMC10237333 DOI: 10.1093/femsyr/foad029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 05/01/2023] [Accepted: 05/10/2023] [Indexed: 05/15/2023] Open
Abstract
Budding yeast uses the TORC1-Sch9p and cAMP-PKA signalling pathways to regulate adaptations to changing nutrient environments. Dynamic and single-cell measurements of the activity of these cascades will improve our understanding of the cellular adaptation of yeast. Here, we employed the AKAR3-EV biosensor developed for mammalian cells to measure the cellular phosphorylation status determined by Sch9p and PKA activity in budding yeast. Using various mutant strains and inhibitors, we show that AKAR3-EV measures the Sch9p- and PKA-dependent phosphorylation status in intact yeast cells. At the single-cell level, we found that the phosphorylation responses are homogenous for glucose, sucrose, and fructose, but heterogeneous for mannose. Cells that start to grow after a transition to mannose correspond to higher normalized Förster resonance energy transfer (FRET) levels, in line with the involvement of Sch9p and PKA pathways to stimulate growth-related processes. The Sch9p and PKA pathways have a relatively high affinity for glucose (K0.5 of 0.24 mM) under glucose-derepressed conditions. Lastly, steady-state FRET levels of AKAR3-EV seem to be independent of growth rates, suggesting that Sch9p- and PKA-dependent phosphorylation activities are transient responses to nutrient transitions. We believe that the AKAR3-EV sensor is an excellent addition to the biosensor arsenal for illuminating cellular adaptation in single yeast cells.
Collapse
Affiliation(s)
- Dennis Botman
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Sineka Kanagasabapathi
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Philipp Savakis
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| | - Bas Teusink
- Systems Biology Lab, AIMMS/A-LIFE, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
| |
Collapse
|
3
|
Botman D, O’Toole TG, Goedhart J, Bruggeman FJ, van Heerden JH, Teusink B. A yeast FRET biosensor enlightens cAMP signaling. Mol Biol Cell 2021; 32:1229-1240. [PMID: 33881352 PMCID: PMC8351543 DOI: 10.1091/mbc.e20-05-0319] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 04/08/2021] [Accepted: 04/16/2021] [Indexed: 11/12/2022] Open
Abstract
The cAMP-PKA signaling cascade in budding yeast regulates adaptation to changing environments. We developed yEPAC, a FRET-based biosensor for cAMP measurements in yeast. We used this sensor with flow cytometry for high-throughput single cell-level quantification during dynamic changes in response to sudden nutrient transitions. We found that the characteristic cAMP peak differentiates between different carbon source transitions and is rather homogenous among single cells, especially for transitions to glucose. The peaks are mediated by a combination of extracellular sensing and intracellular metabolism. Moreover, the cAMP peak follows the Weber-Fechner law; its height scales with the relative, and not the absolute, change in glucose. Last, our results suggest that the cAMP peak height conveys information about prospective growth rates. In conclusion, our yEPAC-sensor makes possible new avenues for understanding yeast physiology, signaling, and metabolic adaptation.
Collapse
Affiliation(s)
- Dennis Botman
- Systems Biology Lab/AIMMS, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - Tom G. O’Toole
- Department of Molecular Cell Biology and Immunology, Vrije University Medical Center, 1081 HV Amsterdam, The Netherlands
| | - Joachim Goedhart
- Section of Molecular Cytology, van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - Frank J. Bruggeman
- Systems Biology Lab/AIMMS, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - Johan H. van Heerden
- Systems Biology Lab/AIMMS, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - Bas Teusink
- Systems Biology Lab/AIMMS, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| |
Collapse
|
4
|
Chen A, Ju Z, Wang J, Wang J, Wang H, Wu J, Yin Y, Zhao Y, Ma Z, Chen Y. The RasGEF FgCdc25 regulates fungal development and virulence in Fusarium graminearum via cAMP and MAPK signalling pathways. Environ Microbiol 2020; 22:5109-5124. [PMID: 32537857 DOI: 10.1111/1462-2920.15129] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 11/29/2022]
Abstract
Ras GTPases act as molecular switches to control various cellular processes by coupling integrated signals in eukaryotes. Activities of Ras GTPases are triggered by Ras GTPase guanine nucleotide exchange factors (RasGEFs) in general, whereas the role of RasGEF in plant pathogenic fungi is largely unknown. In this study, we characterized the only RasGEF protein in Fusarium graminearum, FgCdc25, by combining genetic, cytological and phenotypic strategies. FgCdc25 directly interacted with RasGTPase FgRas2, but not FgRas1, to regulate growth and sexual reproduction. Mutation of the FgCDC25 gene resulted in decreased toxisome formation and deoxynivalenol (DON) production, which was largely depended on cAMP signalling. In addition, FgCdc25 indirectly interacted with FgSte11 in FgSte11-Ste7-Gpmk1 cascade, and the ΔFgcdc25 strain totally abolished the formation of infection structures and was nonpathogenic in planta, which was partially recovered by addition of exogenous cAMP. In contrast, FgCdc25 directly interplayed with FgBck1 in FgBck1-MKK1-Mgv1 cascade to negatively control cell wall integrity. Collectively, these results suggest that FgCdc25 modulates cAMP and MAPK signalling pathways and further regulates fungal development, DON production and plant infection in F. graminearum.
Collapse
Affiliation(s)
- Ahai Chen
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Zhenzhen Ju
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Jinli Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Jing Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Hongkai Wang
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Jiayu Wu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Yanni Yin
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Zhonghua Ma
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| | - Yun Chen
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.,Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, 310058, China
| |
Collapse
|
5
|
Fructose-1,6-bisphosphate couples glycolytic flux to activation of Ras. Nat Commun 2017; 8:922. [PMID: 29030545 PMCID: PMC5640605 DOI: 10.1038/s41467-017-01019-z] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/14/2017] [Indexed: 12/12/2022] Open
Abstract
Yeast and cancer cells share the unusual characteristic of favoring fermentation of sugar over respiration. We now reveal an evolutionary conserved mechanism linking fermentation to activation of Ras, a major regulator of cell proliferation in yeast and mammalian cells, and prime proto-oncogene product. A yeast mutant (tps1∆) with overactive influx of glucose into glycolysis and hyperaccumulation of Fru1,6bisP, shows hyperactivation of Ras, which causes its glucose growth defect by triggering apoptosis. Fru1,6bisP is a potent activator of Ras in permeabilized yeast cells, likely acting through Cdc25. As in yeast, glucose triggers activation of Ras and its downstream targets MEK and ERK in mammalian cells. Biolayer interferometry measurements show that physiological concentrations of Fru1,6bisP stimulate dissociation of the pure Sos1/H-Ras complex. Thermal shift assay confirms direct binding to Sos1, the mammalian ortholog of Cdc25. Our results suggest that the Warburg effect creates a vicious cycle through Fru1,6bisP activation of Ras, by which enhanced fermentation stimulates oncogenic potency. Yeast and cancer cells both favor sugar fermentation in aerobic conditions. Here the authors describe a conserved mechanism from yeast to mammals where the glycolysis intermediate fructose-1,6-bisphosphate binds Cdc25/Sos1 and couples increased glycolytic flux to increased Ras proto-oncoprotein activity.
Collapse
|
6
|
Abstract
For centuries yeast species have been popular hosts for classical biotechnology processes, such as baking, brewing, and wine making, and more recently for recombinant proteins production, thanks to the advantages of unicellular organisms (i.e., ease of genetic manipulation and rapid growth) together with the ability to perform eukaryotic posttranslational modifications. Moreover, yeast cells have been used for few decades as a tool for identifying the genes and pathways involved in basic cellular processes such as the cell cycle, aging, and stress response. In the budding yeast S. cerevisiae the Ras/cAMP/PKA pathway is directly involved in the regulation of metabolism, cell growth, stress resistance, and proliferation in response to the availability of nutrients and in the adaptation to glucose, controlling cytosolic cAMP levels and consequently the cAMP-dependent protein kinase (PKA) activity. Moreover, Ras signalling has been identified in several pathogenic yeasts as a key controller for virulence, due to its involvement in yeast morphogenesis. Nowadays, yeasts are still useful for Ras-like proteins investigation, both as model organisms and as a test tube to study variants of heterologous Ras-like proteins.
Collapse
Affiliation(s)
- Renata Tisi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | | | | |
Collapse
|
7
|
Busti S, Coccetti P, Alberghina L, Vanoni M. Glucose signaling-mediated coordination of cell growth and cell cycle in Saccharomyces cerevisiae. SENSORS 2010; 10:6195-240. [PMID: 22219709 PMCID: PMC3247754 DOI: 10.3390/s100606195] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 05/26/2010] [Accepted: 05/27/2010] [Indexed: 01/05/2023]
Abstract
Besides being the favorite carbon and energy source for the budding yeast Sacchromyces cerevisiae, glucose can act as a signaling molecule to regulate multiple aspects of yeast physiology. Yeast cells have evolved several mechanisms for monitoring the level of glucose in their habitat and respond quickly to frequent changes in the sugar availability in the environment: the cAMP/PKA pathways (with its two branches comprising Ras and the Gpr1/Gpa2 module), the Rgt2/Snf3-Rgt1 pathway and the main repression pathway involving the kinase Snf1. The cAMP/PKA pathway plays the prominent role in responding to changes in glucose availability and initiating the signaling processes that promote cell growth and division. Snf1 (the yeast homologous to mammalian AMP-activated protein kinase) is primarily required for the adaptation of yeast cell to glucose limitation and for growth on alternative carbon source, but it is also involved in the cellular response to various environmental stresses. The Rgt2/Snf3-Rgt1 pathway regulates the expression of genes required for glucose uptake. Many interconnections exist between the diverse glucose sensing systems, which enables yeast cells to fine tune cell growth, cell cycle and their coordination in response to nutritional changes.
Collapse
Affiliation(s)
- Stefano Busti
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano Bicocca, Piazza della Scienza, 2-20126 Milano, Italy.
| | | | | | | |
Collapse
|
8
|
Tisi R, Belotti F, Paiardi C, Brunetti F, Martegani E. The budding yeast RasGEF Cdc25 reveals an unexpected nuclear localization. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2363-74. [DOI: 10.1016/j.bbamcr.2008.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 09/10/2008] [Accepted: 09/10/2008] [Indexed: 11/26/2022]
|
9
|
Paiardi C, Belotti F, Colombo S, Tisi R, Martegani E. The large N-terminal domain of Cdc25 protein of the yeast Saccharomyces cerevisiae is required for glucose-induced Ras2 activation. FEMS Yeast Res 2007; 7:1270-5. [PMID: 17727662 DOI: 10.1111/j.1567-1364.2007.00300.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The Saccharomyces cerevisiae CDC25 gene encodes a guanine nucleotide exchange factor for Ras proteins whose catalytic domain is highly homologous to Ras-guanine nucleotide exchange factors from higher eukaryotes. In this study, glucose-induced Ras activation and cAMP response were investigated in mutants lacking the N-terminal domain of Cdc25 or where the entire CDC25 coding sequence was substituted by an expression cassette for a mammalian guanine nucleotide exchange factor catalytic domain. Our results suggest that an unregulated, low Ras guanine nucleotide exchange factor activity allows a normal glucose-induced cAMP signal that appears to be mediated mainly by the Gpr1/Gpa2 system, but it was not enough to sustain the glucose-induced increase of Ras2-GTP normally observed in a wild-type strain.
Collapse
Affiliation(s)
- Chiara Paiardi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
| | | | | | | | | |
Collapse
|
10
|
Belotti F, Tisi R, Martegani E. The N-terminal region of the Saccharomyces cerevisiae RasGEF Cdc25 is required for nutrient-dependent cell-size regulation. MICROBIOLOGY-SGM 2006; 152:1231-1242. [PMID: 16549685 DOI: 10.1099/mic.0.28683-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In the yeast Saccharomyces cerevisiae, the Cdc25/Ras/cAMP/protein kinase A (PKA) pathway plays a major role in the control of metabolism, stress resistance and proliferation, in relation to the available nutrients and conditions. The budding yeast RasGEF Cdc25 was the first RasGEF to be identified in any organism, but very little is known about its activity regulation. Recently, it was suggested that the dispensable N-terminal domain of Cdc25 could negatively control the catalytic activity of the protein. In order to investigate the role of this domain, strains were constructed that produced two different versions of the C-terminal domain of Cdc25 (aa 907-1589 and 1147-1589). The carbon-source-dependent cell size control mechanism present in the wild type was found in the first of these mutants, but was lost in the second mutant, for which the cell size, determined as protein content, was the same during exponential growth in both ethanol- and glucose-containing media. A biparametric analysis demonstrated that this effect was essentially due to the inability of the mutant producing the shorter sequence to modify its protein content at budding. A similar phenotype was observed in strains that lacked CDC25, but which possessed a mammalian GEF catalytic domain. Taken together, these results suggest that Cdc25 is involved in the regulation of cell size in the presence of different carbon sources. Moreover, production of the aa 876-1100 fragment increased heat-stress resistance in the wild-type strain, and rescued heat-shock sensitivity in the ira1Delta background. Further work will aim to clarify the role of this region in Cdc25 activity and Ras/cAMP pathway regulation.
Collapse
Affiliation(s)
- Fiorella Belotti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Renata Tisi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Enzo Martegani
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| |
Collapse
|
11
|
Folch-Mallol JL, Martínez LM, Casas SJ, Yang R, Martínez-Anaya C, López L, Hernández A, Nieto-Sotelo J. New roles for CDC25 in growth control, galactose regulation and cellular differentiation in Saccharomyces cerevisiae. MICROBIOLOGY-SGM 2005; 150:2865-2879. [PMID: 15347746 DOI: 10.1099/mic.0.27144-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Living organisms display large differences in stress resistance throughout their life cycles. To study the coordinated regulation of development and stress responses in exponentially growing yeast, mutants that displayed elevated heat-shock resistance at this stage were screened for. Here, two new mutant alleles of CDC25 in Saccharomyces cerevisiae, cdc25-21 and cdc25-22, are described. During exponential growth in glucose at 25 degrees C, these mutants are resistant to heat, oxidative, osmotic and ionic shock, accumulate stress-protein transcripts, show slow growth rates, thick cell walls and glycogen hyperaccumulation and lack cAMP signalling in response to glucose. Genetic and cellular analyses revealed that the stationary-phase phenotypes of cdc25-21 and cdc25-22 mutants are not due to entrance to a G(0) state during exponential growth, but are the result of a prolonged G(1) phase. It was found that, in the W303 background, CDC25 is dispensable for growth in glucose media. However, CDC25 is essential for growth in galactose, in non-fermentable carbon sources and under continuous incubation at 38 degrees C. In conclusion, the function of the catalytic, C-terminal domain of Cdc25p is not only important for fermentative growth, but also for growth in non-fermentable carbon sources and to trigger galactose derepression.
Collapse
Affiliation(s)
- Jorge Luis Folch-Mallol
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| | - Luz María Martínez
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| | - Sergio J Casas
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| | - Runying Yang
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| | - Claudia Martínez-Anaya
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| | - Lorena López
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| | - Alejandra Hernández
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| | - Jorge Nieto-Sotelo
- Department of Plant Molecular Biology, Instituto de Biotecnología de la UNAM, 62250 Cuernavaca, Mor., Mexico
| |
Collapse
|
12
|
Maidan MM, De Rop L, Serneels J, Exler S, Rupp S, Tournu H, Thevelein JM, Van Dijck P. The G protein-coupled receptor Gpr1 and the Galpha protein Gpa2 act through the cAMP-protein kinase A pathway to induce morphogenesis in Candida albicans. Mol Biol Cell 2005; 16:1971-86. [PMID: 15673611 PMCID: PMC1073676 DOI: 10.1091/mbc.e04-09-0780] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We investigated the role in cell morphogenesis and pathogenicity of the Candida albicans GPR1 gene, encoding the G protein-coupled receptor Gpr1. Deletion of C. albicans GPR1 has only minor effects in liquid hypha-inducing media but results in strong defects in the yeast-to-hypha transition on solid hypha-inducing media. Addition of cAMP, expression of a constitutively active allele of the Galpha protein Gpa2 or of the catalytic protein kinase A subunit TPK1 restores the wild-type phenotype of the CaGPR1-deleted strain. Overexpression of HST7, encoding a component of the mitogen-activated protein kinase pathway, does not suppress the defect in filamentation. These results indicate that CaGpr1 functions upstream in the cAMP-protein kinase A (PKA) pathway. We also show that, in the presence of glucose, CaGpr1 is important for amino acid-induced transition from yeast to hyphal cells. Finally, as opposed to previous reports, we show that CaGpa2 acts downstream of CaGpr1 as activator of the cAMP-PKA pathway but that deletion of neither CaGpr1 nor CaGpa2 affects glucose-induced cAMP signaling. In contrast, the latter is abolished in strains lacking CaCdc25 or CaRas1, suggesting that the CaCdc25-CaRas1 rather than the CaGpr1-CaGpa2 module mediates glucose-induced cAMP signaling in C. albicans.
Collapse
Affiliation(s)
- Mykola M Maidan
- Department of Molecular Microbiology, Flanders Interuniversity Institute for Biotechnology (VIB) and Laboratory of Molecular Cell Biology, Katholieke Universiteit Leuven, Flanders, Belgium
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Colombo S, Ronchetti D, Thevelein JM, Winderickx J, Martegani E. Activation state of the Ras2 protein and glucose-induced signaling in Saccharomyces cerevisiae. J Biol Chem 2004; 279:46715-22. [PMID: 15339905 DOI: 10.1074/jbc.m405136200] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activity of adenylate cyclase in the yeast Saccharomyces cerevisiae is controlled by two G-protein systems, the Ras proteins and the Galpha 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 glucose-induced increase in cAMP. This increase is severely delayed in a strain lacking Cdc25, the guanine nucleotide exchange factor for Ras proteins. Deletion of the Ras-GAPs IRA2 (alone or with IRA1) or the presence of RAS2Val19 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 glucose-induced 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.
Collapse
Affiliation(s)
- Sonia Colombo
- Dipartimento di Biotecnologie e Bioscienze, Università Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | | | | | | | | |
Collapse
|
14
|
Tisi R, Belotti F, Wera S, Winderickx J, Thevelein JM, Martegani E. Evidence for inositol triphosphate as a second messenger for glucose-induced calcium signalling in budding yeast. Curr Genet 2003; 45:83-9. [PMID: 14618376 DOI: 10.1007/s00294-003-0465-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2003] [Revised: 10/21/2003] [Accepted: 10/23/2003] [Indexed: 10/26/2022]
Abstract
The Saccharomyces cerevisiae phospholipase C Plc1 is involved in cytosolic transient glucose-induced calcium increase, which also requires the Gpr1/Gpa2 receptor/G protein complex and glucose hexokinases. Differing from mammalian cells, this increase in cytosolic calcium concentration is mainly due to an influx from the external medium. No inositol triphosphate receptor homologue has been identified in the S. cerevisiae genome; and, therefore, the transduction mechanism from Plc1 activation to calcium flux generation still has to be identified. Inositol triphosphate (IP(3)) in yeast is rapidly transformed into IP(4) and IP(5) by a dual kinase, Arg82. Then another kinase, Ipk1, phosphorylates the IP(5) into IP(6). In mutant cells that do not express either of these kinases, the glucose-induced calcium signal was not only detectable but was even wider than in the wild-type strain. IP(3) accumulation upon glucose addition was completely absent in the plc1Delta strain and was amplified both by deletion of either ARG82 or IPK1 genes and by overexpression of PLC1. These results taken together suggest that Plc1p activation by glucose, leading to cleavage of PIP(2) and generation of IP(3), seems to be sufficient for raising the calcium level in the cytosol. This is the first indication for a physiological role of IP(3) signalling in S. cerevisiae. Many aspects about the signal transduction mechanism and the final effectors require further study.
Collapse
Affiliation(s)
- Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | | | | | | | | | | |
Collapse
|
15
|
Rudoni S, Colombo S, Coccetti P, Martegani E. Role of guanine nucleotides in the regulation of the Ras/cAMP pathway in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1538:181-9. [PMID: 11336789 DOI: 10.1016/s0167-4889(01)00067-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The CDC25 gene product is a guanine nucleotide exchange factor for Ras proteins in yeast. Recently it has been suggested that the intracellular levels of guanine nucleotides may influence the exchange reaction. To test this hypothesis we measured the levels of nucleotides in yeast cells under different growth conditions and the relative amount of Ras2-GTP. The intracellular GTP/GDP ratio was found to be very sensitive to growth conditions: the ratio is high, close to that of ATP/ADP during exponential growth, but it decreases rapidly before the beginning of stationary phase, and it drops further under starvation conditions. The addition of glucose to glucose-starved cells causes a fast increase of the GTP/GDP ratio. The relative amount of Ras2-GTP changes in a parallel way suggesting that there is a correlation with the cytosolic GTP/GDP ratio. In addition 'in vitro' mixed-nucleotide exchange experiments done on purified Ras2 protein demonstrated that the GTP and GDP concentrations influence the extent of Ras2-GTP loading giving further support to their possible regulatory role.
Collapse
Affiliation(s)
- S Rudoni
- Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Italy
| | | | | | | |
Collapse
|
16
|
Nutrient-induced signal transduction through the protein kinase A pathway and its role in the control of metabolism, stress resistance, and growth in yeast. Enzyme Microb Technol 2000; 26:819-825. [PMID: 10862891 DOI: 10.1016/s0141-0229(00)00177-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Yeast cells growing in the presence of glucose or a related rapidly-fermented sugar differ strongly in a variety of physiological properties compared to cells growing in the absence of glucose. Part of these differences appear to be caused by the protein kinase A (PKA) and related signal transduction pathways. Addition of glucose to cells previously deprived of glucose triggers cAMP accumulation, which is apparently mediated by the Gpr1-Gpa2 G-protein coupled receptor system. However, the resulting effect on PKA-controlled properties is only transient when there is no complete growth medium present. When an essential nutrient is lacking, the cells arrest in the stationary phase G0. At the same time they acquire all characteristics of cells with low PKA activity, even if there is ample glucose present. When the essential nutrient is added again, a similar PKA-dependent protein phosphorylation cascade is triggered as observed after addition of glucose to glucose-deprived cells, but which is not cAMP-mediated. Because the pathway involved requires a fermentable carbon source and a complete growth medium, at least for its sustained activation, it has been called "fermentable growth medium (FGM)-induced pathway."
Collapse
|
17
|
Chen RA, Michaeli T, Van Aelst L, Ballester R. A role for the noncatalytic N terminus in the function of Cdc25, a Saccharomyces cerevisiae Ras-guanine nucleotide exchange factor. Genetics 2000; 154:1473-84. [PMID: 10747046 PMCID: PMC1461032 DOI: 10.1093/genetics/154.4.1473] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Saccharomyces cerevisiae CDC25 gene encodes a guanine nucleotide exchange factor (GEF) for Ras proteins. Its catalytic domain is highly homologous to Ras-GEFs from all eukaryotes. Even though Cdc25 is the first Ras-GEF identified in any organism, we still know very little about how its function is regulated in yeast. In this work we provide evidence for the involvement of the N terminus of Cdc25 in the regulation of its activity. A truncated CDC25 lacking the noncatalytic C-terminal coding sequence was identified in a screen of high-copy suppressors of the heat-shock-sensitive phenotype of strains in which the Ras pathway is hyper-activated. The truncated gene acts as a dominant-negative mutant because it only suppresses the heat-shock sensitivity of strains that require the function of CDC25. Our two-hybrid assays and immunoprecipitation analyses show interactions between the N terminus of Cdc25 and itself, the C terminus, and the full-length protein. These results suggest that the dominant-negative effect may be a result of oligomerization with endogenous Cdc25. Further evidence of the role of the N terminus of Cdc25 in the regulation of its activity is provided by the mapping of the activating mutation of CDC25HS20 to the serine residue at position 365 in the noncatalytic N-terminal domain. This mutation induces a phenotype similar to activating mutants of other genes in the Ras pathway in yeast. Hence, the N terminus may exert a negative control on the catalytic activity of the protein. Taken together these results suggest that the N terminus plays a crucial role in regulating Cdc25 and consequently Ras activity, which in S. cerevisiae is essential for cell cycle progression.
Collapse
Affiliation(s)
- R A Chen
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93106, USA
| | | | | | | |
Collapse
|
18
|
Thevelein JM, de Winde JH. Novel sensing mechanisms and targets for the cAMP-protein kinase A pathway in the yeast Saccharomyces cerevisiae. Mol Microbiol 1999; 33:904-18. [PMID: 10476026 DOI: 10.1046/j.1365-2958.1999.01538.x] [Citation(s) in RCA: 474] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cAMP-protein kinase A (PKA) pathway in the yeast Saccharomyces cerevisiae plays a major role in the control of metabolism, stress resistance and proliferation, in particular in connection with the available nutrient conditions. Extensive information has been obtained on the core section of the pathway, i.e. Cdc25, Ras, adenylate cyclase, PKA, and on components interacting directly with this core section, such as the Ira proteins, Cap/Srv2 and the two cAMP phosphodiesterases. Recent work has now started to reveal upstream regulatory components and downstream targets of the pathway. A G-protein-coupled receptor system (Gpr1-Gpa2) acts upstream of adenylate cyclase and is required for glucose activation of cAMP synthesis in concert with a glucose phosphorylation-dependent mechanism. Although a genuine signalling role for the Ras proteins remains unclear, they appear to mediate at least part of the potent stimulation of cAMP synthesis by intracellular acidification. Recently, several new targets of the PKA pathway have been discovered. These include the Msn2 and Msn4 transcription factors mediating part of the induction of STRE-controlled genes by a variety of stress conditions, the Rim15 protein kinase involved in stationary phase induction of a similar set of genes and the Pde1 low-affinity cAMP phosphodiesterase, which specifically controls agonist-induced cAMP signalling. A major issue that remains to be resolved is the precise connection between the cAMP-PKA pathway and other nutrient-regulated components involved in the control of growth and of phenotypic characteristics correlated with growth, such as the Sch9 and Yak1 protein kinases. Cln3 appears to play a crucial role in the connection between the availability of certain nutrients and Cdc28 kinase activity, but it remains to be clarified which nutrient-controlled pathways control Cln3 levels.
Collapse
Affiliation(s)
- J M Thevelein
- Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit Leuven, Kardinaal Mercierlaan 92, B-3001 Leuven-Heverlee, Flanders, Belgium.
| | | |
Collapse
|
19
|
Kraakman L, Lemaire K, Ma P, Teunissen AW, Donaton MC, Van Dijck P, Winderickx J, de Winde JH, Thevelein JM. A Saccharomyces cerevisiae G-protein coupled receptor, Gpr1, is specifically required for glucose activation of the cAMP pathway during the transition to growth on glucose. Mol Microbiol 1999; 32:1002-12. [PMID: 10361302 DOI: 10.1046/j.1365-2958.1999.01413.x] [Citation(s) in RCA: 268] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the yeast Saccharomyces cerevisiae the accumulation of cAMP is controlled by an elaborate pathway. Only two triggers of the Ras adenylate cyclase pathway are known. Intracellular acidification induces a Ras-mediated long-lasting cAMP increase. Addition of glucose to cells grown on a non-fermentable carbon source or to stationary-phase cells triggers a transient burst in the intracellular cAMP level. This glucose-induced cAMP signal is dependent on the G alpha-protein Gpa2. We show that the G-protein coupled receptor (GPCR) Gpr1 interacts with Gpa2 and is required for stimulation of cAMP synthesis by glucose. Gpr1 displays sequence homology to GPCRs of higher organisms. The absence of Gpr1 is rescued by the constitutively activated Gpa2Val-132 allele. In addition, we isolated a mutant allele of GPR1, named fil2, in a screen for mutants deficient in glucose-induced loss of heat resistance, which is consistent with its lack of glucose-induced cAMP activation. Apparently, Gpr1 together with Gpa2 constitute a glucose-sensing system for activation of the cAMP pathway. Deletion of Gpr1 and/or Gpa2 affected cAPK-controlled features (levels of trehalose, glycogen, heat resistance, expression of STRE-controlled genes and ribosomal protein genes) specifically during the transition to growth on glucose. Hence, an alternative glucose-sensing system must signal glucose availability for the Sch9-dependent pathway during growth on glucose. This appears to be the first example of a GPCR system activated by a nutrient in eukaryotic cells. Hence, a subfamily of GPCRs might be involved in nutrient sensing.
Collapse
Affiliation(s)
- L Kraakman
- Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit Leuven, Institute of Botany and Microbiology
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Mintzer KA, Field J. The SH3 domain of the S. cerevisiae Cdc25p binds adenylyl cyclase and facilitates Ras regulation of cAMP signalling. Cell Signal 1999; 11:127-35. [PMID: 10048790 DOI: 10.1016/s0898-6568(98)00044-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Cdc25 and Ras are two proteins required for cAMP signalling in the budding yeast Saccharomyces cerevisiae. Cdc25 is the guanine nucleotide exchange protein that activates Ras. Ras, in turn, activates adenylyl cyclase. Cdc25 has a Src homology 3 (SH3) domain near the N-terminus and a catalytic domain in the C-terminal region. We find that a point mutation in the SH3 domain attenuates cAMP signalling in response to glucose feeding. Furthermore, we demonstrate, by using recombinant adenylyl cyclase and Cdc25, that the SH3 domain of Cdc25 can bind directly to adenylyl cyclase. Binding was specific, because the SH3 domain of Abp1p (actin-binding protein 1), which binds the 70,000 Mr subunit of adenylyl cyclase, CAP/Srv2, failed to bind adenylyl cyclase. A binding site for Cdc25-SH3 localised to the C-terminal catalytic region of adenylyl cyclase. Finally, pre-incubation with Ras enhanced the SH3-bound adenylyl cyclase activity. These studies suggest that a direct interaction between Cdc25 and adenylyl cyclase promotes efficient assembly of the adenylyl cyclase complex.
Collapse
Affiliation(s)
- K A Mintzer
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
| | | |
Collapse
|
21
|
Colombo S, Ma P, Cauwenberg L, Winderickx J, Crauwels M, Teunissen A, Nauwelaers D, de Winde JH, Gorwa MF, Colavizza D, Thevelein JM. Involvement of distinct G-proteins, Gpa2 and Ras, in glucose- and intracellular acidification-induced cAMP signalling in the yeast Saccharomyces cerevisiae. EMBO J 1998; 17:3326-41. [PMID: 9628870 PMCID: PMC1170671 DOI: 10.1093/emboj/17.12.3326] [Citation(s) in RCA: 252] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Adenylate cyclase activity in Saccharomyces cerevisiae is dependent on Ras proteins. Both addition of glucose to glucose-deprived (derepressed) cells and intracellular acidification trigger an increase in the cAMP level in vivo. We show that intracellular acidification, but not glucose, causes an increase in the GTP/GDP ratio on the Ras proteins independent of Cdc25 and Sdc25. Deletion of the GTPase-activating proteins Ira1 and Ira2, or expression of the RAS2(val19) allele, causes an enhanced GTP/GDP basal ratio and abolishes the intracellular acidification-induced increase. In the ira1Delta ira2Delta strain, intracellular acidification still triggers a cAMP increase. Glucose also did not cause an increase in the GTP/GDP ratio in a strain with reduced feedback inhibition of cAMP synthesis. Further investigation indicated that feedback inhibition by cAPK on cAMP synthesis acts independently of changes in the GTP/GDP ratio on Ras. Stimulation by glucose was dependent on the Galpha-protein Gpa2, whose deletion confers the typical phenotype associated with a reduced cAMP level: higher heat resistance, a higher level of trehalose and glycogen and elevated expression of STRE-controlled genes. However, the typical fluctuation in these characteristics during diauxic growth on glucose was still present. Overexpression of Ras2(val19) inhibited both the acidification- and glucose-induced cAMP increase even in a protein kinase A-attenuated strain. Our results suggest that intracellular acidification stimulates cAMP synthesis in vivo at least through activation of the Ras proteins, while glucose acts through the Gpa2 protein. Interaction of Ras2(val19) with adenylate cyclase apparently prevents its activation by both agonists.
Collapse
Affiliation(s)
- S Colombo
- Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit Leuven, Flanders, Belgium
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Sagee S, Sherman A, Shenhar G, Robzyk K, Ben-Doy N, Simchen G, Kassir Y. Multiple and distinct activation and repression sequences mediate the regulated transcription of IME1, a transcriptional activator of meiosis-specific genes in Saccharomyces cerevisiae. Mol Cell Biol 1998; 18:1985-95. [PMID: 9528770 PMCID: PMC121428 DOI: 10.1128/mcb.18.4.1985] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
IME1 encodes a transcriptional activator required for the transcription of meiosis-specific genes and initiation of meiosis in Saccharomyces cerevisiae. The transcription of IME1 is repressed in the presence of glucose, and a low basal level of IME1 RNA is observed in vegetative cultures with acetate as the sole carbon source. Upon nitrogen depletion a transient induction in the transcription of IME1 is observed in MATa/MATalpha diploids but not in MAT-insufficient strains. In this study we demonstrate that the transcription of IME1 is controlled by an extremely unusual large 5' region, over 2,100 bp long. This area is divided into four different upstream controlling sequences (UCS). UCS2 promotes the transcription of IME1 in the presence of a nonfermentable carbon source. UCS2 is flanked by three negative regions: UCS1, which exhibits URS activity in the presence of nitrogen, and UCS3 and UCS4, which repress the activity of UCS2 in MAT-insufficient cells. UCS2 consists of alternate positive and negative elements: three distinct constitutive URS elements that prevent the function of any upstream activating sequence (UAS) under all growth conditions, a constitutive UAS element that promotes expression under all growth conditions, a UAS element that is active only in vegetative media, and two discrete elements that function as UASs in the presence of acetate. Sequence analysis of IME1 revealed the presence of two almost identical 30- to 32-bp repeats. Surprisingly, one repeat, IREd, exhibits constitutive URS activity, whereas the other repeat, IREu, serves as a carbon-source-regulated UAS element. The RAS-cyclic AMP-dependent protein kinase cAPK pathway prevents the UAS activity of IREu in the presence of glucose as the sole carbon source, while the transcriptional activators Msn2p and Msn4p promote the UAS activity of this repeat in the presence of acetate. We suggest that the use of multiple negative and positive elements is essential to restrict transcription to the appropriate conditions and that the combinatorial effect of the entire region leads to the regulated transcription of IME1.
Collapse
Affiliation(s)
- S Sagee
- Faculty of Biology, Technion, Haifa, Israel
| | | | | | | | | | | | | |
Collapse
|
23
|
Christensen ST, Leick V, Rasmussen L, Wheatley DN. Signaling in unicellular eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 1997; 177:181-253. [PMID: 9378617 DOI: 10.1016/s0074-7696(08)62233-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Aspects of intercellular and intracellular signaling systems in cell survival, proliferation, differentiation, chemosensory behavior, and programmed cell death in free-living unicellular eukaryotes have been reviewed. Comparisons have been made with both bacteria and metazoa. The central organisms were flagellates (Trypanosoma, Leishmania, and Crithidia), slime molds (Dictyostelium), yeast cells (Saccharomyces cerevisiae), and ciliates (Paramecium, Euplotes, and Tetrahymena). There are two novel aspects in this review. First, cellular responses are viewed in an evolutionary perspective, rather than from the more prevailing one, in which the unicellular eukaryotes are seen by the mammalian organisms. Second, results obtained with cell cultures in minimal, chemically defined nutrient media at low cell densities where intercellular signaling is strongly reduced are discussed. These results shed light on control mechanisms and their cooperation inside the living cell. Intracellular systems have many common features in unicellular and multicellular organisms.
Collapse
Affiliation(s)
- S T Christensen
- Department of Medical Biochemistry and Genetics, Panum Institute, University of Copenhagen, Denmark
| | | | | | | |
Collapse
|
24
|
Boy-Marcotte E, Ikonomi P, Jacquet M. SDC25, a dispensable Ras guanine nucleotide exchange factor of Saccharomyces cerevisiae differs from CDC25 by its regulation. Mol Biol Cell 1996; 7:529-39. [PMID: 8730097 PMCID: PMC275907 DOI: 10.1091/mbc.7.4.529] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The SDC25 gene of Saccharomyces cerevisiae is homologous to CDC25. Its 3' domain encodes a guanine nucleotide exchange factor (GEF) for Ras. Nevertheless, the GEF encoded by CDC24 is determinant for the Ras/cAMP pathway activation in growth. We demonstrate that the SDC25 gene product is a functional GEF for Ras: the complete SDC25 gene functionally replaces CDC25 when overexpressed or when transcribed under CDC25 transcriptional control at the CDC25 locus. Chimeric proteins between Sdc25p and Cdc25p are also functional GEFs for Ras. We also show that the two genes are differentially regulated: SDC25 is not transcribed at a detectable level in growth conditions when glucose is the carbon source. It is transcribed at the end of growth when nutrients are depleted and in cells grown on nonfermentable carbon sources. In contrast, CDC25 accumulation is slightly reduced when glucose is replaced by a nonfermentable carbon source.
Collapse
Affiliation(s)
- E Boy-Marcotte
- Institut de Génétique et Microbiologie, URA Centre National de la Recherche Scientifique D1354, Université Paris XI, Orsay, France
| | | | | |
Collapse
|
25
|
Boy-Marcotte E, Tadi D, Perrot M, Boucherie H, Jacquet M. High cAMP levels antagonize the reprogramming of gene expression that occurs at the diauxic shift in Saccharomyces cerevisiae. MICROBIOLOGY (READING, ENGLAND) 1996; 142 ( Pt 3):459-467. [PMID: 8868420 DOI: 10.1099/13500872-142-3-459] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In order to analyse the involvement of the cAMP pathway in the regulation of gene expression in Saccharomyces cerevisiae, we have examined the effect of cAMP on protein synthesis by using two-dimensional gel electrophoresis. cAMP had only a minor effect on the protein pattern of cells growing exponentially on glucose. However, it interfered with the changes in gene expression normally occurring upon glucose exhaustion in yeast cultures, maintaining a protein pattern typical of cells growing on glucose. This effect was accompanied by a delay before growth recovery on ethanol. We propose a model in which the cAMP-signalling pathway has a role in the maintenance of gene expression, rather than in the determination of a specific programme. A decrease of cAMP would then be required for metabolic transitions such as the diauxic phase.
Collapse
Affiliation(s)
- Emmanuelle Boy-Marcotte
- Institut de Génétique et Microbiologie, URA CNRS D1354, Université Paris XI, Bâtiment 400, 91405 Orsay Cedex, France
| | - Djamila Tadi
- Institut de Génétique et Microbiologie, URA CNRS D1354, Université Paris XI, Bâtiment 400, 91405 Orsay Cedex, France
| | - Michel Perrot
- Laboratoire de Génétique, UPR CNRS 9026, Avenue des Facultés, 33405 Talence Cedex, France
| | - Helian Boucherie
- Laboratoire de Génétique, UPR CNRS 9026, Avenue des Facultés, 33405 Talence Cedex, France
| | - Michel Jacquet
- Institut de Génétique et Microbiologie, URA CNRS D1354, Université Paris XI, Bâtiment 400, 91405 Orsay Cedex, France
| |
Collapse
|
26
|
Kaplon T, Jacquet M. The cellular content of Cdc25p, the Ras exchange factor in Saccharomyces cerevisiae, is regulated by destabilization through a cyclin destruction box. J Biol Chem 1995; 270:20742-7. [PMID: 7657656 DOI: 10.1074/jbc.270.35.20742] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Cdc25p and Sdc25p proteins were the first members of the family of guanine nucleotide exchange factors to be identified. These proteins promote the formation of active Ras-GTP complex from inactive Ras-GDP complex by exchange of GDP for GTP. Therefore Cdc25p which is the main positive regulator of Ras, regulates through Ras the activity of adenylate cyclase in Saccharomyces cerevisiae. The amino-terminal part of Cdc25p has a sequence similar to the cyclin destruction box (CDB) of mitotic cyclins. This sequence has been reported to be required for ubiquitin-dependent proteolysis. In this study we show that Cdc25p is an unstable polypeptide with a half-life of 15-20 min. Its instability depends upon the presence of the CDB which can also confer instability to other proteins. Degradation of Cdc25p and CDB containing beta-galactosidase was found to be independent of various cell cycle arrest points. The fast degradation of Cdc25p opens the possibility that Ras and the cAMP cascade in yeast are directly modulated by the cellular content of the guanine nucleotide exchange factor rather than variation in activity or localization control.
Collapse
Affiliation(s)
- T Kaplon
- Institut de Génétique et Microbiologie, CNRS URA 1354, Université Paris XI, Orsay, France
| | | |
Collapse
|
27
|
Bhattacharya S, Chen L, Broach JR, Powers S. Ras membrane targeting is essential for glucose signaling but not for viability in yeast. Proc Natl Acad Sci U S A 1995; 92:2984-8. [PMID: 7708760 PMCID: PMC42343 DOI: 10.1073/pnas.92.7.2984] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Ras proteins are small GTP binding proteins that serve as critical relays in a variety of signal transduction pathways in eukaryotic cells. Like most metazoan Ras proteins, yeast Ras is post-translationally modified by addition of a farnesyl and a palmitoyl moiety, and these modifications are required for targeting the protein to the cytoplasmic face of the plasma membrane and for biological activity of the protein. We have constructed mutants of the yeast (Saccharomyces cerevisiae) Ras that are farnesylated in vivo but are not palmitoylated. These mutant proteins are not localized to the plasma membrane but function in the cell as well as the wild-type protein. Such mutants are viable but fail to induce a transient increase in intracellular cAMP concentration in response to glucose addition, although this deficiency does not yield a marked growth phenotype. These results are consistent with the hypothesis that the essential role of the farnesyl moiety on yeast Ras is to enhance productive interaction between Ras and its essential downstream target, adenylyl cyclase, rather than to localize Ras to the plasma membrane.
Collapse
Affiliation(s)
- S Bhattacharya
- Department of Molecular Biology, Princeton University, NJ 08544, USA
| | | | | | | |
Collapse
|
28
|
Hofer F, Fields S, Schneider C, Martin GS. Activated Ras interacts with the Ral guanine nucleotide dissociation stimulator. Proc Natl Acad Sci U S A 1994; 91:11089-93. [PMID: 7972015 PMCID: PMC45172 DOI: 10.1073/pnas.91.23.11089] [Citation(s) in RCA: 223] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The yeast two-hybrid system was used to identify proteins that interact with Ras. The H-Ras protein was found to interact with a guanine nucleotide dissociation stimulator (GDS) that has been previously shown to regulate guanine nucleotide exchange on another member of the Ras protein family, Ral. The interaction is mediated by the C-terminal, noncatalytic segment of the RalGDS and can be detected both in vivo, using the two-hybrid system, and in vitro, with purified recombinant proteins. The interaction of the RalGDS C-terminal segment with Ras is specific, dependent on activation of Ras by GTP, and blocked by a mutation that affects Ras effector function. These characteristics are similar to those previously demonstrated for the interaction between Ras and its putative effector, Raf, suggesting that the RalGDS may also be a Ras effector. Consistent with this idea, the RalGDS was found to inhibit the binding of Raf to Ras.
Collapse
Affiliation(s)
- F Hofer
- Department of Molecular and Cell Biology, University of California, Berkeley 94720-3204
| | | | | | | |
Collapse
|
29
|
Camus C, Boy-Marcotte E, Jacquet M. Two subclasses of guanine exchange factor (GEF) domains revealed by comparison of activities of chimeric genes constructed from CDC25, SDC25 and BUD5 in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1994; 245:167-76. [PMID: 7816024 DOI: 10.1007/bf00283264] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Guanine Exchange Factor (GEF) activity for Ras proteins has been associated with a conserved domain in Cdc25p, Sdc25p in Saccharomyces cerevisiae and several other proteins recently found in other eukaryotes. We have assessed the structure-function relationships between three different members of this family in S. cerevisiae, Cdc25p, Sdc25p and Bud5p. Cdc25p controls the Ras pathway, whereas Bud5p controls bud site localization. We demonstrate that the GEF domain of Sdc25p is closely related to that of Cdc25p. We first constructed a thermosensitive allele of SDC25 by specifically altering amino acid positions known to be changed in the cdc25-1 mutation. Secondly, we constructed three chimeric genes from CDC25 and SDC25, the products of which are as active in the Ras pathway as are the wild-type proteins. In contrast, similar chimeras made between CDC25 and BUD5 lead to proteins that are inactive both in the Ras and budding control pathways. This difference in the ability of chimeric proteins to retain activity allows us to define two subclasses of structurally different GEFs: Cdc25p and Sdc25p are Ras-specific GEFs, and Bud5p is a putative GEF for the Rsr1/Bud1 Rap-like protein.
Collapse
Affiliation(s)
- C Camus
- Laboratoire Information génétique et développement, Institut de Génétique et Microbiologie, URA C.N.R.S, Université, Paris-Sud, Orsay, France
| | | | | |
Collapse
|
30
|
Küntzel H, Rottjakob HW, Schwed A, Zwerschke W. START control in cycling Saccharomyces cerevisiae cells. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1994; 48:1-28. [PMID: 7938547 DOI: 10.1016/s0079-6603(08)60851-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- H Küntzel
- Max-Planck-Institut für Experimentelle Medizin, Göttingen, Germany
| | | | | | | |
Collapse
|
31
|
Kraakman LS, Griffioen G, Zerp S, Groeneveld P, Thevelein JM, Mager WH, Planta RJ. Growth-related expression of ribosomal protein genes in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1993; 239:196-204. [PMID: 8389977 DOI: 10.1007/bf00281618] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The rate of ribosomal protein gene (rp-gene) transcription in yeast is accurately adjusted to the cellular requirement for ribosomes under various growth conditions. However, the molecular mechanisms underlying this co-ordinated transcriptional control have not yet been elucidated. Transcriptional activation of rp-genes is mediated through two different multifunctional transacting factors, ABF1 and RAP1. In this report, we demonstrate that changes in cellular rp-mRNA levels during varying growth conditions are not parallelled by changes in the in vitro binding capacity of ABF1 or RAP1 for their cognate sequences. In addition, the nutritional upshift response of rp-genes observed after addition of glucose to a culture growing on a non-fermentative carbon source turns out not to be the result of increased expression of the ABF1 and RAP1 genes or of elevated DNA-binding activity of these factors. Therefore, growth rate-dependent transcription regulation of rp-genes is most probably not mediated by changes in the efficiency of binding of ABF1 and RAP1 to the upstream activation sites of these genes, but rather through other alterations in the efficiency of transcription activation. Furthermore, we tested the possibility that cAMP may play a role in elevating rp-gene expression during a nutritional shift-up. We found that the nutritional upshift response occurs normally in several mutants defective in cAMP metabolism.
Collapse
Affiliation(s)
- L S Kraakman
- Department of Biochemistry and Molecular Biology, Vrije Universiteit, Amsterdam, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
Transport of sugars is a fundamental property of all eukaryotic cells. Of particular importance is the uptake of glucose, a preferred carbon and energy source. The rate of glucose utilization in yeast is often dictated by the activity and concentration of glucose transporters in the plasma membrane. Given the importance of transport as a site of control of glycolytic flux, the regulation of glucose transporters is necessarily complex. The molecular analysis of these transporters in Saccharomyces has revealed the existence of a multigene family of sugar carriers. Recent data have raised the question of the actual role of all of these proteins in sugar catabolism, as some appear to be lowly expressed, and point mutations of these genes may confer pleiotropic phenotypes, inconsistent with a simple role as catabolic transporters. The transporters themselves appear to be intimately involved in the process of sensing glucose, a model for which there is growing support.
Collapse
Affiliation(s)
- L F Bisson
- Department of Viticulture and Enology, University of California, Davis 95616-8749
| | | | | | | |
Collapse
|
33
|
Thevelein JM. The RAS-adenylate cyclase pathway and cell cycle control in Saccharomyces cerevisiae. Antonie Van Leeuwenhoek 1992; 62:109-30. [PMID: 1444331 DOI: 10.1007/bf00584466] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The cell cycle of Saccharomyces cerevisiae contains a decision point in G1 called 'start', which is composed of two specific sites. Nutrient-starved cells arrest at the first site while pheromone-treated cells arrest at the second site. Functioning of the RAS-adenylate cyclase pathway is required for progression over the nutrient-starvation site while overactivation of the pathway renders the cells unable to arrest at this site. However, progression of cycling cells over the nutrient-starvation site does not appear to be triggered by the RAS-adenylate cyclase pathway in response to a specific stimulus, such as an exogenous nutrient. The essential function of the pathway appears to be limited to provision of a basal level of cAMP. cAMP-dependent protein kinase rather than cAMP might be the universal integrator of nutrient availability in yeast. On the other hand stimulation of the pathway in glucose-derepressed yeast cells by rapidly-fermented sugars, such as glucose, is well documented and might play a role in the control of the transition from gluconeogenic growth to fermentative growth. The initial trigger of this signalling pathway is proposed to reside in a 'glucose sensing complex' which has both a function in controlling the influx of glucose into the cell and in activating in addition to the RAS-adenylate cyclase pathway all other glucose-induced regulatory pathways in yeast. Two crucial problems remaining to be solved with respect to cell cycle control are the nature of the connection between the RAS-adenylate cyclase pathway and nitrogen-source induced progression over the nutrient-starvation site of 'start' and second the nature of the downstream processes linking the RAS-adenylate cyclase pathway to Cyclin/CDC28 controlled progression over the pheromone site of 'start'.
Collapse
Affiliation(s)
- J M Thevelein
- Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit te Leuven, Heverlee, Flanders, Belgium
| |
Collapse
|
34
|
dos Passos JB, Vanhalewyn M, Brandão RL, Castro IM, Nicoli JR, Thevelein JM. Glucose-induced activation of plasma membrane H(+)-ATPase in mutants of the yeast Saccharomyces cerevisiae affected in cAMP metabolism, cAMP-dependent protein phosphorylation and the initiation of glycolysis. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1136:57-67. [PMID: 1322708 DOI: 10.1016/0167-4889(92)90085-p] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Addition of glucose-related fermentable sugars or protonophores to derepressed cells of the yeast Saccharomyces cerevisiae causes a 3- to 4-fold activation of the plasma membrane H(+)-ATPase within a few minutes. These conditions are known to cause rapid increases in the cAMP level. In yeast strains carrying temperature-sensitive mutations in genes required for cAMP synthesis, incubation at the restrictive temperature reduced the extent of H(+)-ATPase activation. Incubation of non-temperature-sensitive strains, however, at such temperatures also caused reduction of H(+)-ATPase activation. Yeast strains which are specifically deficient in the glucose-induced cAMP increase (and not in basal cAMP synthesis) still showed plasma membrane H(+)-ATPase activation. Yeast mutants with widely divergent activity levels of cAMP-dependent protein kinase displayed very similar levels of activation of the plasma membrane H(+)-ATPase. This was also true for a yeast mutant carrying a deletion in the CDC25 gene. These results show that the cAMP-protein kinase A signaling pathway is not required for glucose activation of the H(+)-ATPase. They also contradict the specific requirement of the CDC25 gene product. Experiments with yeast strains carrying point or deletion mutations in the genes coding for the sugar phosphorylating enzymes hexokinase PI and PII and glucokinase showed that activation of the H(+)-ATPase with glucose or fructose was completely dependent on the presence of a kinase able to phosphorylate the sugar. These and other data concerning the role of initial sugar metabolism in triggering activation are consistent with the idea that the glucose-induced activation pathways of cAMP-synthesis and H(+)-ATPase have a common initiation point.
Collapse
Affiliation(s)
- J B dos Passos
- Laboratorium voor Moleculaire Celbiologie, Katholieke Universiteit, Leuven, Belgium
| | | | | | | | | | | |
Collapse
|
35
|
Martegani E, Vanoni M, Zippel R, Coccetti P, Brambilla R, Ferrari C, Sturani E, Alberghina L. Cloning by functional complementation of a mouse cDNA encoding a homologue of CDC25, a Saccharomyces cerevisiae RAS activator. EMBO J 1992; 11:2151-7. [PMID: 1376246 PMCID: PMC556682 DOI: 10.1002/j.1460-2075.1992.tb05274.x] [Citation(s) in RCA: 163] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae genetic and biochemical evidence indicates that the product of the CDC25 gene activates the RAS/adenylyl cyclase/protein kinase A pathway by acting as a guanine nucleotide protein. Here we report the isolation of a mouse brain cDNA homologous to CDC25. The mouse cDNA, called CDC25Mm, complements specifically point mutations and deletion/disruptions of the CDC25 gene. In addition, it restores the cAMP levels and CDC25-dependent glucose-induced cAMP signalling in a yeast strain bearing a disruption of the CDC25 gene. The CDC25Mm-encoded protein is 34% identical with the catalytic carboxy terminal part of the CDC25 protein and shares significant homology with other proteins belonging to the same family. The protein encoded by CDC25Mm, prepared as a glutathione S-transferase fusion in Escherichia coli cells, activates adenylyl cyclase in yeast membranes in a RAS2-dependent manner. Northern blot analysis of mouse brain poly(A)+ RNA reveals two major transcripts of approximately 1700 and 5200 nucleotides. Transcripts were found also in mouse heart and at a lower level in liver and spleen.
Collapse
Affiliation(s)
- E Martegani
- Dipartimento di Fisiologia e Biochimica Generali, Università degli Studi di Milano, Italy
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Hohmann S, Huse K, Valentin E, Mbonyi K, Thevelein JM, Zimmermann FK. Glucose-induced regulatory defects in the Saccharomyces cerevisiae byp1 growth initiation mutant and identification of MIG1 as a partial suppressor. J Bacteriol 1992; 174:4183-8. [PMID: 1597433 PMCID: PMC206133 DOI: 10.1128/jb.174.12.4183-4188.1992] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Saccharomyces cerevisiae byp1-3 mutants displayed a long lag phase when shifted from a nonfermentable carbon source to a medium containing glucose. The byp1-3 mutation also caused several defects in regulatory phenomena which occur during the transition from the derepressed state to the repressed state. As opposed to wild-type cells, the addition of glucose to cells of the byp1-3 mutant grown on nonfermentable carbon sources did not induce a cyclic AMP signal. Fructose-2,6-bisphosphate formation and inactivation of fructose-1,6-bisphosphatase were severely delayed, but trehalase activation was not affected. In addition, the induction of pyruvate decarboxylase both at the level of activity and that of transcription was very slow compared with that in wild-type cells. These pleotropic defects in glucose-induced regulatory phenomena might be responsible for the very long lag phase of byp1-3 cells and the inability of ascospores to initiate growth after germination on glucose media. Screening of a yeast gene library for clones complementing the byp1-3 phenotype resulted in the isolation of a truncated form of the previously described zinc finger transcription repressor MIG1. The entire MIG1 gene and the truncated form suppressed even on a single-copy vector the growth initiation defect but not the regulatory abnormalities of the byp1-3 mutant. MIG1 is not allelic to byp1-3.
Collapse
Affiliation(s)
- S Hohmann
- Institut für Mikrobiologie, Technische Hochschule Darmstadt, Germany
| | | | | | | | | | | |
Collapse
|
37
|
González MI, Stucka R, Blázquez MA, Feldmann H, Gancedo C. Molecular cloning of CIF1, a yeast gene necessary for growth on glucose. Yeast 1992; 8:183-92. [PMID: 1315471 DOI: 10.1002/yea.320080304] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The cif1 mutation of Saccharomyces cerevisiae (Navon et al., Biochemistry 18, 4487-4499, 1979) causes inability to grow on glucose and absence of catabolite inactivation. We have cloned the CIF1 gene by complementation of function and located it in a 2.75 kb SphI-BstEII fragment situated at ca. 18 kb centromere distal of LYS2 and ca. 80 kb centromere proximal of TYR1 on chromosome II. Southern analysis demonstrated that CIF1 is present in a single copy in the yeast genome. Northern analysis revealed that the corresponding mRNA of 1.8 kb is more abundant in cells grown on galactose than in those grown on glucose. A protein of ca. 54 kDa was predicted from the open reading frame in the sequenced fragment. In strains carrying the cif1 mutation the intracellular concentration of ATP decreased immediately after addition of glucose while the intracellular concentration of cAMP did not increase. cAMP concentration increased in response to galactose or 2,4-dinitrophenol. Disruption of BCY1 or overexpression of CDC25 in a cif1 background did not restore growth on glucose, suggesting that the absence of cAMP signal is not the primary cause of lack of growth on glucose. Complementation tests showed that cif1 is not allelic to fdp1 although the two genes seem to be functionally related.
Collapse
Affiliation(s)
- M I González
- Instituto de Investigaciones Biomédicas C.S.I.C., Facultad de Medicina UAM, Madrid, Spain
| | | | | | | | | |
Collapse
|
38
|
Abstract
Molecular genetics has proved quite successful in identifying the components of RAS-mediated signal transduction in the yeast Saccharomyces cerevisiae and in defining the nature of their interactions. Recently, the emphasis has shifted to a biochemical approach as the processes of guanine nucleotide exchange, GTPase stimulation activity and posttranslational modification of Ras proteins have all been reproduced in vitro.
Collapse
Affiliation(s)
- J R Broach
- Department of Molecular Biology, Princeton University, New Jersey 08544
| |
Collapse
|
39
|
Thevelein JM. Fermentable sugars and intracellular acidification as specific activators of the RAS-adenylate cyclase signalling pathway in yeast: the relationship to nutrient-induced cell cycle control. Mol Microbiol 1991; 5:1301-7. [PMID: 1664904 DOI: 10.1111/j.1365-2958.1991.tb00776.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The RAS proteins of the yeast Saccharomyces cerevisiae fulfil a similar control function on yeast adenylate cyclase as the mammalian Gs proteins on mammalian adenylate cyclase. The discovery that glucose and other fermentable sugars act as specific activators of the RAS-adenylate cyclase pathway in yeast appeared to offer a mechanism for the way in which at least one nutrient would control progression over the start point in the G1 phase of the yeast cell cycle by means of this pathway. Recently, however, evidence has been obtained to show that the glucose-activation pathway of adenylate cyclase is a glucose-repressible pathway and therefore not operative during growth on glucose. In addition, mutant strains were obtained which lack the glucose-activation pathway and show normal exponential growth on glucose. This appears to confine the physiological role of this pathway to control of the transition from the derepressed state (growth on respirative carbon sources) to the repressed state (growth on fermentative carbon sources) by means of an already well-documented cAMP-triggered protein phosphorylation cascade. Intracellular acidification also stimulates the RAS-adenylate cyclase pathway, which might constitute a rescue mechanism for cells suffering from stress conditions. The presence of a nitrogen source does not stimulate the RAS-adenylate cyclase pathway. Although other nutrient signals for the pathway might still be discovered, it appears more and more likely that the well-known requirement of cAMP for progression over the start point of the yeast cell cycle is limited to providing a basal cAMP level rather than acting as a second messenger for an extracellular signal.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- J M Thevelein
- Laboratorium voor Cellulaire Biochemie, Katholieke Universiteit te Leuven, Belgium
| |
Collapse
|