1
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Chumley MM, Khasawneh FA, Otto A, Gedeon T. A Nonlinear Delay Model for Metabolic Oscillations in Yeast Cells. Bull Math Biol 2023; 85:122. [PMID: 37934330 DOI: 10.1007/s11538-023-01227-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 10/19/2023] [Indexed: 11/08/2023]
Abstract
We introduce two time-delay models of metabolic oscillations in yeast cells. Our model tests a hypothesis that the oscillations occur as multiple pathways share a limited resource which we equate to the number of available ribosomes. We initially explore a single-protein model with a constraint equation governing the total resource available to the cell. The model is then extended to include three proteins that share a resource pool. Three approaches are considered at constant delay to numerically detect oscillations. First, we use a spectral element method to approximate the system as a discrete map and evaluate the stability of the linearized system about its equilibria by examining its eigenvalues. For the second method, we plot amplitudes of the simulation trajectories in 2D projections of the parameter space. We use a history function that is consistent with published experimental results to obtain metabolic oscillations. Finally, the spectral element method is used to convert the system to a boundary value problem whose solutions correspond to approximate periodic solutions of the system. Our results show that certain combinations of total resource available and the time delay, lead to oscillations. We observe that an oscillation region in the parameter space is between regions admitting steady states that correspond to zero and constant production. Similar behavior is found with the three-protein model where all proteins require the same production time. However, a shift in the protein production rates peaks occurs for low available resource suggesting that our model captures the shared resource pool dynamics.
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Affiliation(s)
- Max M Chumley
- Mechanical Engineering, Michigan State University, East Lansing, MI, USA
| | - Firas A Khasawneh
- Mechanical Engineering, Michigan State University, East Lansing, MI, USA.
| | - Andreas Otto
- Institute of Physics, Chemnitz University of Technology, 09107, Chemnitz, Germany
- Fraunhofer Institute for Machine Tools and Forming Technology IWU, Reichenhainer Str. 88, 09126, Chemnitz, Germany
| | - Tomas Gedeon
- Mathematical Sciences, Montana State University, Bozeman, MT, USA
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2
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Minden S, Aniolek M, Noorman H, Takors R. Mimicked Mixing-Induced Heterogeneities of Industrial Bioreactors Stimulate Long-Lasting Adaption Programs in Ethanol-Producing Yeasts. Genes (Basel) 2023; 14:genes14050997. [PMID: 37239357 DOI: 10.3390/genes14050997] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/24/2023] [Accepted: 04/26/2023] [Indexed: 05/28/2023] Open
Abstract
Commercial-scale bioreactors create an unnatural environment for microbes from an evolutionary point of view. Mixing insufficiencies expose individual cells to fluctuating nutrient concentrations on a second-to-minute scale while transcriptional and translational capacities limit the microbial adaptation time from minutes to hours. This mismatch carries the risk of inadequate adaptation effects, especially considering that nutrients are available at optimal concentrations on average. Consequently, industrial bioprocesses that strive to maintain microbes in a phenotypic sweet spot, during lab-scale development, might suffer performance losses when said adaptive misconfigurations arise during scale-up. Here, we investigated the influence of fluctuating glucose availability on the gene-expression profile in the industrial yeast Ethanol Red™. The stimulus-response experiment introduced 2 min glucose depletion phases to cells growing under glucose limitation in a chemostat. Even though Ethanol Red™ displayed robust growth and productivity, a single 2 min depletion of glucose transiently triggered the environmental stress response. Furthermore, a new growth phenotype with an increased ribosome portfolio emerged after complete adaptation to recurring glucose shortages. The results of this study serve a twofold purpose. First, it highlights the necessity to consider the large-scale environment already at the experimental development stage, even when process-related stressors are moderate. Second, it allowed the deduction of strain engineering guidelines to optimize the genetic background of large-scale production hosts.
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Affiliation(s)
- Steven Minden
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Maria Aniolek
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
| | - Henk Noorman
- Royal DSM, 2613 AX Delft, The Netherlands
- Department of Biotechnology, Delft University of Technology, 2628 CD Delft, The Netherlands
| | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, 70569 Stuttgart, Germany
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3
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Minden S, Aniolek M, Noorman H, Takors R. Performing in spite of starvation: How Saccharomyces cerevisiae maintains robust growth when facing famine zones in industrial bioreactors. Microb Biotechnol 2022; 16:148-168. [PMID: 36479922 PMCID: PMC9803336 DOI: 10.1111/1751-7915.14188] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/08/2022] [Accepted: 11/13/2022] [Indexed: 12/13/2022] Open
Abstract
In fed-batch operated industrial bioreactors, glucose-limited feeding is commonly applied for optimal control of cell growth and product formation. Still, microbial cells such as yeasts and bacteria are frequently exposed to glucose starvation conditions in poorly mixed zones or far away from the feedstock inlet point. Despite its commonness, studies mimicking related stimuli are still underrepresented in scale-up/scale-down considerations. This may surprise as the transition from glucose limitation to starvation has the potential to provoke regulatory responses with negative consequences for production performance. In order to shed more light, we performed gene-expression analysis of Saccharomyces cerevisiae grown in intermittently fed chemostat cultures to study the effect of limitation-starvation transitions. The resulting glucose concentration gradient was representative for the commercial scale and compelled cells to tolerate about 76 s with sub-optimal substrate supply. Special attention was paid to the adaptation status of the population by discriminating between first time and repeated entry into the starvation regime. Unprepared cells reacted with a transiently reduced growth rate governed by the general stress response. Yeasts adapted to the dynamic environment by increasing internal growth capacities at the cost of rising maintenance demands by 2.7%. Evidence was found that multiple protein kinase A (PKA) and Snf1-mediated regulatory circuits were initiated and ramped down still keeping the cells in an adapted trade-off between growth optimization and down-regulation of stress response. From this finding, primary engineering guidelines are deduced to optimize both the production host's genetic background and the design of scale-down experiments.
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Affiliation(s)
- Steven Minden
- Institute of Biochemical EngineeringUniversity of StuttgartStuttgartGermany
| | - Maria Aniolek
- Institute of Biochemical EngineeringUniversity of StuttgartStuttgartGermany
| | - Henk Noorman
- Royal DSMDelftThe Netherlands,Department of BiotechnologyDelft University of TechnologyDelftThe Netherlands
| | - Ralf Takors
- Institute of Biochemical EngineeringUniversity of StuttgartStuttgartGermany
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4
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Prathom K, Young TR. Universality of stable multi-cluster periodic solutions in a population model of the cell cycle with negative feedback. JOURNAL OF BIOLOGICAL DYNAMICS 2021; 15:455-522. [PMID: 34490835 DOI: 10.1080/17513758.2021.1971781] [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: 02/23/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
We study a population model where cells in one part of the cell cycle may affect the progress of cells in another part. If the influence, or feedback, from one part to another is negative, simulations of the model almost always result in multiple temporal clusters formed by groups of cells. We study regions in parameter space where periodic 'k-cyclic' solutions are stable. The regions of stability coincide with sub-triangles on which certain events occur in a fixed order. For boundary sub-triangles with order 'rs1', we prove that the k-cyclic periodic solution is asymptotically stable if the index of the sub-triangle is relatively prime with respect to the number of clusters k and neutrally stable otherwise. For negative linear feedback, we prove that the interior of the parameter set is covered by stable sub-triangles, i.e. a stable k-cyclic solution always exists for some k. We observe numerically that the result also holds for many forms of nonlinear feedback, but may break down in extreme cases.
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5
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Nguyen TM, Telek S, Zicler A, Martinez JA, Zacchetti B, Kopp J, Slouka C, Herwig C, Grünberger A, Delvigne F. Reducing phenotypic instabilities of a microbial population during continuous cultivation based on cell switching dynamics. Biotechnol Bioeng 2021; 118:3847-3859. [PMID: 34129251 DOI: 10.1002/bit.27860] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/11/2021] [Accepted: 06/12/2021] [Indexed: 12/19/2022]
Abstract
Predicting the fate of individual cells among a microbial population (i.e., growth and gene expression) remains a challenge, especially when this population is exposed to very dynamic environmental conditions, such as those encountered during continuous cultivation. Indeed, the dynamic nature of a continuous cultivation process implies the potential diversification of the microbial population resulting in genotypic and phenotypic heterogeneity. The present work focused on the induction of the arabinose operon in Escherichia coli as a model system to study this diversification process in continuous cultivations. As a preliminary step, the green fluorescent protein (GFP) level triggered by an arabinose-inducible ParaBAD promoter was tracked by flow cytometry in chemostat cultivations with glucose-arabinose co-feeding. For a wide range of glucose-arabinose co-feeding concentrations in the chemostats, the simultaneous occurrence of GFP positive and negative subpopulation was observed. In the second set of experiments, continuous cultivation was performed by adding glucose continuously and arabinose based on the capability of individual cells to switch from low GFP to high GFP expression states, performed with a technology setup called segregostat. In the segregostat cultivation mode, on-line flow cytometry analysis was used for adjusting the arabinose/glucose transitions based on the phenotypic switching profiles of the microbial population. This strategy allowed finding an appropriate arabinose pulsing frequency, leading to prolonged maintenance of the induction level with a limited increase in the phenotypic diversity for more than 60 generations. The results suggest that the steady forcing of individual cells into a given phenotypic trajectory may not be the best strategy for controlling cell populations. Instead, allowing individual cells to switch periodically around a predefined threshold seems to be a more robust strategy leading to oscillations, but within a predictable cell population behavior range.
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Affiliation(s)
- Thai M Nguyen
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Samuel Telek
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Andrew Zicler
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Juan A Martinez
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Boris Zacchetti
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Julian Kopp
- Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical, Environmental and Biological Engineering, Vienna University of Technology, Vienna, Austria
| | - Christoph Slouka
- Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical, Environmental and Biological Engineering, Vienna University of Technology, Vienna, Austria
| | - Christoph Herwig
- Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical, Environmental and Biological Engineering, Vienna University of Technology, Vienna, Austria.,Research Division Biochemical Engineering, Institute of Chemical Environmental and Bioscience Engineering, Vienna University of Technology, Vienna, Austria
| | - Alexander Grünberger
- Multiscale Bioengineering, Technical Faculty, Bielefeld Germany & CeBiTec, Bielefeld University, Bielefeld, Germany
| | - Frank Delvigne
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
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6
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Oh TJ, Fan H, Skeeters SS, Zhang K. Steering Molecular Activity with Optogenetics: Recent Advances and Perspectives. Adv Biol (Weinh) 2021; 5:e2000180. [PMID: 34028216 PMCID: PMC8218620 DOI: 10.1002/adbi.202000180] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/14/2020] [Indexed: 12/24/2022]
Abstract
Optogenetics utilizes photosensitive proteins to manipulate the localization and interaction of molecules in living cells. Because light can be rapidly switched and conveniently confined to the sub-micrometer scale, optogenetics allows for controlling cellular events with an unprecedented resolution in time and space. The past decade has witnessed an enormous progress in the field of optogenetics within the biological sciences. The ever-increasing amount of optogenetic tools, however, can overwhelm the selection of appropriate optogenetic strategies. Considering that each optogenetic tool may have a distinct mode of action, a comparative analysis of the current optogenetic toolbox can promote the further use of optogenetics, especially by researchers new to this field. This review provides such a compilation that highlights the spatiotemporal accuracy of current optogenetic systems. Recent advances of optogenetics in live cells and animal models are summarized, the emerging work that interlinks optogenetics with other research fields is presented, and exciting clinical and industrial efforts to employ optogenetic strategy toward disease intervention are reported.
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Affiliation(s)
- Teak-Jung Oh
- 600 South Mathews Avenue, 314 B Roger Adams Laboratory, Urbana, IL, 61801, USA
| | - Huaxun Fan
- 600 South Mathews Avenue, 314 B Roger Adams Laboratory, Urbana, IL, 61801, USA
| | - Savanna S Skeeters
- 600 South Mathews Avenue, 314 B Roger Adams Laboratory, Urbana, IL, 61801, USA
| | - Kai Zhang
- 600 South Mathews Avenue, 314 B Roger Adams Laboratory, Urbana, IL, 61801, USA
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7
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Dengler L, Örd M, Schwab LM, Loog M, Ewald JC. Regulation of trehalase activity by multi-site phosphorylation and 14-3-3 interaction. Sci Rep 2021; 11:962. [PMID: 33441790 PMCID: PMC7806596 DOI: 10.1038/s41598-020-80357-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 12/17/2020] [Indexed: 11/16/2022] Open
Abstract
Protein phosphorylation enables a rapid adjustment of cellular activities to diverse intracellular and environmental stimuli. Many phosphoproteins are targeted on more than one site, which allows the integration of multiple signals and the implementation of complex responses. However, the hierarchy and interplay between multiple phospho-sites are often unknown. Here, we study multi‐site phosphorylation using the yeast trehalase Nth1 and its activator, the 14-3-3 protein Bmh1, as a model. Nth1 is known to be phosphorylated by the metabolic kinase PKA on four serine residues and by the cell cycle kinase CDK on one residue. However, how these five phospho-sites adjust Nth1 activity remains unclear. Using a novel reporter construct, we investigated the contribution of the individual sites for the regulation of the trehalase and its 14-3-3 interactor. In contrast to the constitutively phosphorylated S20 and S83, the weaker sites S21 and S60 are only phosphorylated by increased PKA activity. For binding Bmh1, S83 functions as the high‐affinity “gatekeeper” site, but successful binding of the Bmh1 dimer and thus Nth1 activation requires S60 as a secondary site. Under nutrient-poor conditions with low PKA activity, S60 is not efficiently phosphorylated and the cell cycle dependent phosphorylation of S66 by Cdk1 contributes to Nth1 activity, likely by providing an alternative Bmh1 binding site. Additionally, the PKA sites S20 and S21 modulate the dephosphorylation of Nth1 on downstream Bmh1 sites. In summary, our results expand our molecular understanding of Nth1 regulation and provide a new aspect of the interaction of 14-3-3 proteins with their targets.
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Affiliation(s)
- Lisa Dengler
- Interfaculty Institute of Cell Biology, University of Tübingen, 72076, Tübingen, Germany
| | - Mihkel Örd
- Institute of Technology, University of Tartu, 50411, Tartu, Estonia
| | - Lucca M Schwab
- Interfaculty Institute of Cell Biology, University of Tübingen, 72076, Tübingen, Germany
| | - Mart Loog
- Institute of Technology, University of Tartu, 50411, Tartu, Estonia
| | - Jennifer C Ewald
- Interfaculty Institute of Cell Biology, University of Tübingen, 72076, Tübingen, Germany.
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8
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Matencio A, García-Carmona F, López-Nicolás JM. Characterization of Resveratrol, Oxyresveratrol, Piceatannol and Roflumilast as Modulators of Phosphodiesterase Activity. Study of Yeast Lifespan. Pharmaceuticals (Basel) 2020; 13:E225. [PMID: 32872677 PMCID: PMC7559934 DOI: 10.3390/ph13090225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/14/2020] [Accepted: 08/28/2020] [Indexed: 11/19/2022] Open
Abstract
Our desire to live longer has led to an ever-increasing number of novel antiaging products. However, few molecules have any real effect and new ones need to be studied before they can be used commercially. In this contribution, activation of the caloric restriction (CR) pathway was studied using different three (resveratrol, oxyresveratrol and piceatannol)-a family with demonstrated bioactivity on phosphodiesterase activity. The high-affinity phosphodiesterase type 2 (PDE2) of Saccharomyces cerevisiae was expressed in Escherichia coli, purified and characterized. The activity and the inhibitory activity of each stilbene was studied, and the findings were compared in vitro and in silico with those obtained with roflumilast-a human PDE4 inhibitor widely used in chronic obstructive pulmonary diseases. Finally, an in vivo chronological lifespan assay using WT S. cerevisiae and ΔPDE2 S. cerevisiae strains was carried out. It was demonstrated that stilbenes can modulate yPDE2 activity, increasing the lifespan of the yeast by 18% over a control (in combination with other pathways). In addition, roflumilast increased the lifespan in the WT strain. The findings as a whole would increase the range of lifespan products available and suggest novel uses for approved drugs.
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Affiliation(s)
| | | | - José Manuel López-Nicolás
- Departamento de Bioquímica y Biología Molecular A, Unidad Docente de Biología, Facultad de Veterinaria, Regional Campus of International Excellence “Campus Mare Nostrum”, Universidad de Murcia, 30003 Murcia, Spain; (A.M.); (F.G.-C.)
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9
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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.
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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
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10
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Zhang L, Winkler S, Schlottmann FP, Kohlbacher O, Elias JE, Skotheim JM, Ewald JC. Multiple Layers of Phospho-Regulation Coordinate Metabolism and the Cell Cycle in Budding Yeast. Front Cell Dev Biol 2019; 7:338. [PMID: 31921850 PMCID: PMC6927922 DOI: 10.3389/fcell.2019.00338] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 11/29/2019] [Indexed: 01/20/2023] Open
Abstract
The coordination of metabolism and growth with cell division is crucial for proliferation. While it has long been known that cell metabolism regulates the cell division cycle, it is becoming increasingly clear that the cell division cycle also regulates metabolism. In budding yeast, we previously showed that over half of all measured metabolites change concentration through the cell cycle indicating that metabolic fluxes are extensively regulated during cell cycle progression. However, how this regulation is achieved still remains poorly understood. Since both the cell cycle and metabolism are regulated to a large extent by protein phosphorylation, we here decided to measure the phosphoproteome through the budding yeast cell cycle. Specifically, we chose a cell cycle synchronization strategy that avoids stress and nutrient-related perturbations of metabolism, and we grew the yeast on ethanol minimal medium to force cells to utilize their full biosynthetic repertoire. Using a tandem-mass-tagging approach, we found over 200 sites on metabolic enzymes and transporters to be phospho-regulated. These sites were distributed among many pathways including carbohydrate catabolism, lipid metabolism, and amino acid synthesis and therefore likely contribute to changing metabolic fluxes through the cell cycle. Among all one thousand sites whose phosphorylation increases through the cell cycle, the CDK consensus motif and an arginine-directed motif were highly enriched. This arginine-directed R-R-x-S motif is associated with protein-kinase A, which regulates metabolism and promotes growth. Finally, we also found over one thousand sites that are dephosphorylated through the G1/S transition. We speculate that the phosphatase Glc7/PP1, known to regulate both the cell cycle and carbon metabolism, may play an important role because its regulatory subunits are phospho-regulated in our data. In summary, our results identify extensive cell cycle dependent phosphorylation and dephosphorylation of metabolic enzymes and suggest multiple mechanisms through which the cell division cycle regulates metabolic signaling pathways to temporally coordinate biosynthesis with distinct phases of the cell division cycle.
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Affiliation(s)
- Lichao Zhang
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, United States
| | - Sebastian Winkler
- Applied Bioinformatics, Department of Computer Science, University of Tübingen, Tübingen, Germany
| | - Fabian P. Schlottmann
- Molecular Cell Biology, Interfaculty Institute of Cell Biology, University of Tübingen, Tübingen, Germany
| | - Oliver Kohlbacher
- Applied Bioinformatics, Department of Computer Science, University of Tübingen, Tübingen, Germany
- Institute for Translational Bioinformatics, University Hospital Tübingen, Tübingen, Germany
- Institute for Bioinformatics and Medical Informatics, University of Tübingen, Tübingen, Germany
- Quantitative Biology Center, University of Tübingen, Tübingen, Germany
- Biomolecular Interactions, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Josh E. Elias
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, United States
| | - Jan M. Skotheim
- Department of Biology, Stanford University, Stanford, CA, United States
| | - Jennifer C. Ewald
- Molecular Cell Biology, Interfaculty Institute of Cell Biology, University of Tübingen, Tübingen, Germany
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11
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Vamvakas SS, Kapolos J, Farmakis L, Koskorellou G, Genneos F. Ser625 of msn2 transcription factor is indispensable for ethanol tolerance and alcoholic fermentation process. Biotechnol Prog 2019; 35:e2837. [PMID: 31087774 DOI: 10.1002/btpr.2837] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/03/2019] [Accepted: 05/08/2019] [Indexed: 11/11/2022]
Abstract
The genetic modification of yeast strains can be used as an approach for the improvement of ethanol fermentation. msn2p transcription factor is implicated in yeast stress response and its activation is controlled by protein kinase A (PKA). PKA activation inhibits the translocation of msn2p to the nucleus. An in silico analysis of msn2 protein sequence revealed serine residue at position 625 as a potent target of PKA. Thus, substitution of this serine residue with alanine increases the susceptibility of the cells to ethanol challenge reducing IC50 from 3% vol/vol to 2.42% vol/vol. Additionally, cells carrying this substitution were shown a significantly reduced fermentation rate at 30°C and 18°C increasing the total fermentation time by approximately two and three times, respectively. These results clearly indicate that Ser625 is absolutely necessary for yeast to retain its fermentation ability and ethanol tolerance.
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Affiliation(s)
| | - John Kapolos
- Deparment of Food Technology, Technological Educational Institute of Peloponnese, Kalamata, Greece
| | - Lambros Farmakis
- Deparment of Food Technology, Technological Educational Institute of Peloponnese, Kalamata, Greece
| | - Gregoria Koskorellou
- Deparment of Food Technology, Technological Educational Institute of Peloponnese, Kalamata, Greece
| | - Fotios Genneos
- Deparment of Food Technology, Technological Educational Institute of Peloponnese, Kalamata, Greece
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12
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Alblova M, Smidova A, Kalabova D, Lentini Santo D, Obsil T, Obsilova VO. Allosteric activation of yeast enzyme neutral trehalase by calcium and 14-3-3 protein. Physiol Res 2019; 68:147-160. [DOI: 10.33549/physiolres.933950] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Neutral trehalase 1 (Nth1) from Saccharomyces cerevisiae catalyzes disaccharide trehalose hydrolysis and helps yeast to survive adverse conditions, such as heat shock, starvation or oxidative stress. 14-3-3 proteins, master regulators of hundreds of partner proteins, participate in many key cellular processes. Nth1 is activated by phosphorylation followed by 14-3-3 protein (Bmh) binding. The activation mechanism is also potentiated by Ca(2+) binding within the EF-hand-like motif. This review summarizes the current knowledge about trehalases and the molecular and structural basis of Nth1 activation. The crystal structure of fully active Nth1 bound to 14-3-3 protein provided the first high-resolution view of a trehalase from a eukaryotic organism and showed 14-3-3 proteins as structural modulators and allosteric effectors of multi-domain binding partners.
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Affiliation(s)
- M. Alblova
- Department of Structural Biology of Signaling Proteins, Division BIOCEV, Institute of Physiology of the Czech Academy of Sciences, Vestec, Czech Republic.
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13
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Causton HC. Metabolic rhythms: A framework for coordinating cellular function. Eur J Neurosci 2018; 51:1-12. [PMID: 30548718 DOI: 10.1111/ejn.14296] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 11/13/2018] [Accepted: 11/19/2018] [Indexed: 01/02/2023]
Abstract
Circadian clocks are widespread among eukaryotes and generally involve feedback loops coupled with metabolic processes and redox balance. The organising power of these oscillations has not only allowed organisms to anticipate day-night cycles, but also acts to temporally compartmentalise otherwise incompatible processes, enhance metabolic efficiency, make the system more robust to noise and propagate signals among cells. While daily rhythms and the function of the circadian transcription-translation loop have been the subject of extensive research over the past four decades, cycles of shorter period and respiratory oscillations, with which they are intertwined, have received less attention. Here, we describe features of yeast respiratory oscillations, which share many features with daily and 12 hr cellular oscillations in animal cells. This relatively simple system enables the analysis of dynamic rhythmic changes in metabolism, independent of cellular oscillations that are a product of the circadian transcription-translation feedback loop. Knowledge gained from studying ultradian oscillations in yeast will lead to a better understanding of the basic mechanistic principles and evolutionary origins of oscillatory behaviour among eukaryotes.
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Affiliation(s)
- Helen C Causton
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York City, New York
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14
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Miller KJ, Box WG, Boulton CA, Smart KA. Cell Cycle Synchrony of Propagated and Recycled Lager Yeast and its Impact on Lag Phase in Fermenter. JOURNAL OF THE AMERICAN SOCIETY OF BREWING CHEMISTS 2018. [DOI: 10.1094/asbcj-2011-1216-01] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Katherine J. Miller
- Division of Food Sciences, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Wendy G. Box
- Division of Food Sciences, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Christopher A. Boulton
- Division of Food Sciences, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Katherine A. Smart
- Division of Food Sciences, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
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15
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Laporte D, Jimenez L, Gouleme L, Sagot I. Yeast quiescence exit swiftness is influenced by cell volume and chronological age. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 5:104-111. [PMID: 29417058 PMCID: PMC5798409 DOI: 10.15698/mic2018.02.615] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/29/2017] [Indexed: 01/12/2023]
Abstract
Quiescence exit swiftness is crucial not only for micro-organisms in competition for an environmental niche, such as yeast, but also for the maintenance of tissue homeostasis in multicellular species. Here we explore the effect of replicative and chronological age on Saccharomyces cerevisiae quiescence exit efficiency. Our study reveals that this step strongly relies on the cell volume in quiescence but is not influenced by cell replicative age, at least for cells that have undergone less than 10 divisions. Furthermore, we establish that chronological age strongly impinges on cell's capacities to exit quiescence. This effect is not related to cell volume or due to cell's inability to metabolize external glucose but rather seems to depend on intracellular trehalose concentration. Overall, our data illustrate that the quiescent state is a continuum evolving with time, early and deep quiescence being distinguishable by the cell's proficiency to re-enter the proliferation cycle.
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Affiliation(s)
- Damien Laporte
- CNRS, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, UMR5095 - 33077 Bordeaux cedex, France
| | - Laure Jimenez
- CNRS, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, UMR5095 - 33077 Bordeaux cedex, France
| | - Laëtitia Gouleme
- CNRS, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, UMR5095 - 33077 Bordeaux cedex, France
| | - Isabelle Sagot
- CNRS, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, UMR5095 - 33077 Bordeaux cedex, France
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16
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Zhao G, Chen Y, Carey L, Futcher B. Cyclin-Dependent Kinase Co-Ordinates Carbohydrate Metabolism and Cell Cycle in S. cerevisiae. Mol Cell 2017; 62:546-57. [PMID: 27203179 DOI: 10.1016/j.molcel.2016.04.026] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 03/17/2016] [Accepted: 04/21/2016] [Indexed: 01/15/2023]
Abstract
Cyclin-dependent kinases (CDKs) control cell division in eukaryotes by phosphorylating proteins involved in division. But successful proliferation requires co-ordination between division and cellular growth in mass. Previous proteomic studies suggested that metabolic proteins, as well as cell division proteins, could potentially be substrates of cyclin-dependent kinases. Here we focus on two metabolic enzymes of the yeast S. cerevisiae, neutral trehalase (Nth1) and glycogen phosphorylase (Gph1), and show that their activities are likely directly controlled by CDK activity, thus allowing co-ordinate regulation of carbohydrate metabolism with cell division processes. In this case, co-ordinate regulation may optimize the decision to undertake a final cell division as nutrients are being exhausted. Co-regulation of cell division processes and metabolic processes by CDK activity may be a general phenomenon important for co-ordinating the cell cycle with growth.
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Affiliation(s)
- Gang Zhao
- Department of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Yuping Chen
- Department of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794, USA; Graduate Program in Genetics, Stony Brook University, Stony Brook, NY 11794, USA
| | - Lucas Carey
- Department of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Bruce Futcher
- Department of Molecular Genetics & Microbiology, Stony Brook University, Stony Brook, NY 11794, USA.
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17
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Ewald JC, Kuehne A, Zamboni N, Skotheim JM. The Yeast Cyclin-Dependent Kinase Routes Carbon Fluxes to Fuel Cell Cycle Progression. Mol Cell 2017; 62:532-45. [PMID: 27203178 DOI: 10.1016/j.molcel.2016.02.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 10/26/2015] [Accepted: 02/11/2016] [Indexed: 01/12/2023]
Abstract
Cell division entails a sequence of processes whose specific demands for biosynthetic precursors and energy place dynamic requirements on metabolism. However, little is known about how metabolic fluxes are coordinated with the cell division cycle. Here, we examine budding yeast to show that more than half of all measured metabolites change significantly through the cell division cycle. Cell cycle-dependent changes in central carbon metabolism are controlled by the cyclin-dependent kinase (Cdk1), a major cell cycle regulator, and the metabolic regulator protein kinase A. At the G1/S transition, Cdk1 phosphorylates and activates the enzyme Nth1, which funnels the storage carbohydrate trehalose into central carbon metabolism. Trehalose utilization fuels anabolic processes required to reliably complete cell division. Thus, the cell cycle entrains carbon metabolism to fuel biosynthesis. Because the oscillation of Cdk activity is a conserved feature of the eukaryotic cell cycle, we anticipate its frequent use in dynamically regulating metabolism for efficient proliferation.
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Affiliation(s)
- Jennifer C Ewald
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Andreas Kuehne
- Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland; PhD Program Systems Biology, Life Science Zurich Graduate School, 8057 Zurich, Switzerland
| | - Nicola Zamboni
- Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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18
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Mellor J. The molecular basis of metabolic cycles and their relationship to circadian rhythms. Nat Struct Mol Biol 2017; 23:1035-1044. [PMID: 27922609 DOI: 10.1038/nsmb.3311] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 09/23/2016] [Indexed: 12/12/2022]
Abstract
Metabolic cycles result from the partitioning of oxidative and reductive metabolism into rhythmic phases of gene expression and oscillating post-translational protein modifications. Relatively little is known about how these switches in gene expression are controlled, although recent studies have suggested that transcription itself may play a central role. This review explores the molecular basis of the metabolic and gene-expression oscillations in the yeast Saccharomyces cerevisiae, as well as how they relate to other biological time-keeping mechanisms, such as circadian rhythms.
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Affiliation(s)
- Jane Mellor
- Department of Biochemistry, University of Oxford, Oxford, UK
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19
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Papagiannakis A, Niebel B, Wit EC, Heinemann M. Autonomous Metabolic Oscillations Robustly Gate the Early and Late Cell Cycle. Mol Cell 2016; 65:285-295. [PMID: 27989441 DOI: 10.1016/j.molcel.2016.11.018] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 09/26/2016] [Accepted: 11/09/2016] [Indexed: 10/20/2022]
Abstract
Eukaryotic cell division is known to be controlled by the cyclin/cyclin dependent kinase (CDK) machinery. However, eukaryotes have evolved prior to CDKs, and cells can divide in the absence of major cyclin/CDK components. We hypothesized that an autonomous metabolic oscillator provides dynamic triggers for cell-cycle initiation and progression. Using microfluidics, cell-cycle reporters, and single-cell metabolite measurements, we found that metabolism of budding yeast is a CDK-independent oscillator that oscillates across different growth conditions, both in synchrony with and also in the absence of the cell cycle. Using environmental perturbations and dynamic single-protein depletion experiments, we found that the metabolic oscillator and the cell cycle form a system of coupled oscillators, with the metabolic oscillator separately gating and maintaining synchrony with the early and late cell cycle. Establishing metabolism as a dynamic component within the cell-cycle network opens new avenues for cell-cycle research and therapeutic interventions for proliferative disorders.
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Affiliation(s)
- Alexandros Papagiannakis
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
| | - Bastian Niebel
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
| | - Ernst C Wit
- Probability and Statistics, Johann Bernoulli Institute of Mathematics and Computer Science, University of Groningen, Nijenborgh 9, 9747 AG Groningen, the Netherlands
| | - Matthias Heinemann
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
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20
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Golkowski M, Shimizu-Albergine M, Suh HW, Beavo JA, Ong SE. Studying mechanisms of cAMP and cyclic nucleotide phosphodiesterase signaling in Leydig cell function with phosphoproteomics. Cell Signal 2015; 28:764-78. [PMID: 26643407 DOI: 10.1016/j.cellsig.2015.11.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 11/26/2015] [Indexed: 12/21/2022]
Abstract
Many cellular processes are modulated by cyclic AMP and nucleotide phosphodiesterases (PDEs) regulate this second messenger by catalyzing its breakdown. The major unique function of testicular Leydig cells is to produce testosterone in response to luteinizing hormone (LH). Treatment of Leydig cells with PDE inhibitors increases cAMP levels and the activity of its downstream effector, cAMP-dependent protein kinase (PKA), leading to a series of kinase-dependent signaling and transcription events that ultimately increase testosterone release. We have recently shown that PDE4B and PDE4C as well as PDE8A and PDE8B are expressed in rodent Leydig cells and that combined inhibition of PDE4 and PDE8 leads to dramatically increased steroid biosynthesis. Here we investigated the effect of PDE4 and PDE8 inhibition on the molecular mechanisms of cAMP actions in a mouse MA10 Leydig cell line model with SILAC mass spectrometry-based phosphoproteomics. We treated MA10 cells either with PDE4 family specific inhibitor (Rolipram) and PDE8 family specific inhibitor (PF-04957325) alone or in combination and quantified the resulting phosphorylation changes at five different time points between 0 and 180min. We identified 28,336 phosphosites from 4837 proteins and observed significant regulation of 749 sites in response to PDE4 and PDE8 inhibitor treatment. Of these, 132 phosphosites were consensus PKA sites. Our data strongly suggest that PDE4 and PDE8 inhibitors synergistically regulate phosphorylation of proteins required for many different cellular processes, including cell cycle progression, lipid and glucose metabolism, transcription, endocytosis and vesicle transport. Our data suggests that cAMP, PDE4 and PDE8 coordinate steroidogenesis by acting on not one rate-limiting step but rather multiple pathways. Moreover, the pools of cAMP controlled by these PDEs also coordinate many other metabolic processes that may be regulated to assure timely and sufficient testosterone secretion in response to LH.
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Affiliation(s)
- Martin Golkowski
- Department of Pharmacology, School of Medicine, University of Washington, USA
| | | | - Hyong Won Suh
- Department of Pharmacology, School of Medicine, University of Washington, USA
| | - Joseph A Beavo
- Department of Pharmacology, School of Medicine, University of Washington, USA.
| | - Shao-En Ong
- Department of Pharmacology, School of Medicine, University of Washington, USA.
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21
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Quan Z, Cao L, Tang Y, Yan Y, Oliver SG, Zhang N. The Yeast GSK-3 Homologue Mck1 Is a Key Controller of Quiescence Entry and Chronological Lifespan. PLoS Genet 2015; 11:e1005282. [PMID: 26103122 PMCID: PMC4477894 DOI: 10.1371/journal.pgen.1005282] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 05/14/2015] [Indexed: 02/06/2023] Open
Abstract
Upon starvation for glucose or any other core nutrient, yeast cells exit from the mitotic cell cycle and acquire a set of G0-specific characteristics to ensure long-term survival. It is not well understood whether or how cell cycle progression is coordinated with the acquisition of different G0-related features during the transition to stationary phase (SP). Here, we identify the yeast GSK-3 homologue Mck1 as a key regulator of G0 entry and reveal that Mck1 acts in parallel to Rim15 to activate starvation-induced gene expression, the acquisition of stress resistance, the accumulation of storage carbohydrates, the ability of early SP cells to exit from quiescence, and their chronological lifespan. FACS and microscopy imaging analyses indicate that Mck1 promotes mother-daughter cell separation and together with Rim15, modulates cell size. This indicates that the two kinases coordinate the transition-phase cell cycle, cell size and the acquisition of different G0-specific features. Epistasis experiments place MCK1, like RIM15, downstream of RAS2 in antagonising cell growth and activating stress resistance and glycogen accumulation. Remarkably, in the ras2∆ cells, deletion of MCK1 and RIM15 together, compared to removal of either of them alone, compromises respiratory growth and enhances heat tolerance and glycogen accumulation. Our data indicate that the nutrient sensor Ras2 may prevent the acquisition of G0-specific features via at least two pathways. One involves the negative regulation of the effectors of G0 entry such as Mck1 and Rim15, while the other likely to involve its functions in promoting respiratory growth, a phenotype also contributed by Mck1 and Rim15.
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Affiliation(s)
- Zhenzhen Quan
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Lu Cao
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Yingzhi Tang
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Yanchun Yan
- Graduate school of Chinese Academy of Agricultural Sciences, Zhongguancun, Beijing, PR China
| | - Stephen G. Oliver
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Nianshu Zhang
- Cambridge Systems Biology Centre and Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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22
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Wang D, Chen F, Wei G, Jiang M, Dong M. The mechanism of improved pullulan production by nitrogen limitation in batch culture of Aureobasidium pullulans. Carbohydr Polym 2015; 127:325-31. [PMID: 25965490 DOI: 10.1016/j.carbpol.2015.03.079] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 03/25/2015] [Accepted: 03/27/2015] [Indexed: 11/17/2022]
Abstract
Batch culture of Aureobasidium pullulans CCTCC M 2012259 for pullulan production at different concentrations of ammonium sulfate and yeast extract was investigated. Increased pullulan production was obtained under nitrogen-limiting conditions, as compared to that without nitrogen limitation. The mechanism of nitrogen limitation favoring to pullulan overproduction was revealed by determining the activity as well as gene expression of key enzymes, and energy supply for pullulan biosynthesis. Results indicated that nitrogen limitation increased the activities of α-phosphoglucose mutase and glucosyltransferase, up-regulated the transcriptional levels of pgm1 and fks genes, and supplied more ATP intracellularly, which were propitious to further pullulan biosynthesis. The economic analysis of batch pullulan production indicated that nitrogen limitation could reduce more than one third of the cost of raw materials when glucose was supplemented to a total concentration of 70 g/L. This study also helps to understand the mechanism of other polysaccharide overproduction by nitrogen limitation.
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Affiliation(s)
- Dahui Wang
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China; School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, PR China
| | - Feifei Chen
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, PR China
| | - Gongyuan Wei
- School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, PR China
| | - Min Jiang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, Nanjing 210009, PR China
| | - Mingsheng Dong
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China.
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23
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Ultradian metabolic rhythm in the diazotrophic cyanobacterium Cyanothece sp. ATCC 51142. Proc Natl Acad Sci U S A 2013; 110:13210-5. [PMID: 23878254 DOI: 10.1073/pnas.1301171110] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The unicellular cyanobacterium Cyanothece sp. American Type Culture Collection (ATCC) 51142 is capable of performing oxygenic photosynthesis during the day and microoxic nitrogen fixation at night. These mutually exclusive processes are possible only by temporal separation by circadian clock or another cellular program. We report identification of a temperature-dependent ultradian metabolic rhythm that controls the alternating oxygenic and microoxic processes of Cyanothece sp. ATCC 51142 under continuous high irradiance and in high CO2 concentration. During the oxygenic photosynthesis phase, nitrate deficiency limited protein synthesis and CO2 assimilation was directed toward glycogen synthesis. The carbohydrate accumulation reduced overexcitation of the photosynthetic reactions until a respiration burst initiated a transition to microoxic N2 fixation. In contrast to the circadian clock, this ultradian period is strongly temperature-dependent: 17 h at 27 °C, which continuously decreased to 10 h at 39 °C. The cycle was expressed by an oscillatory modulation of net O2 evolution, CO2 uptake, pH, fluorescence emission, glycogen content, cell division, and culture optical density. The corresponding ultradian modulation was also observed in the transcription of nitrogenase-related nifB and nifH genes and in nitrogenase activities. We propose that the control by the newly identified metabolic cycle adds another rhythmic component to the circadian clock that reflects the true metabolic state depending on the actual temperature, irradiance, and CO2 availability.
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24
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Abstract
For unicellular organisms, the decision to enter the cell cycle can be viewed most fundamentally as a metabolic problem. A cell must assess its nutritional and metabolic status to ensure it can synthesize sufficient biomass to produce a new daughter cell. The cell must then direct the appropriate metabolic outputs to ensure completion of the division process. Herein, we discuss the changes in metabolism that accompany entry to, and exit from, the cell cycle for the unicellular eukaryote Saccharomyces cerevisiae. Studies of budding yeast under continuous, slow-growth conditions have provided insights into the essence of these metabolic changes at unprecedented temporal resolution. Some of these mechanisms by which cell growth and proliferation are coordinated with metabolism are likely to be conserved in multicellular organisms. An improved understanding of the metabolic basis of cell cycle control promises to reveal fundamental principles governing tumorigenesis, metazoan development, niche expansion, and many additional aspects of cell and organismal growth control.
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Affiliation(s)
- Ling Cai
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038, USA.
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25
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Young TR, Fernandez B, Buckalew R, Moses G, Boczko EM. Clustering in cell cycle dynamics with general response/signaling feedback. J Theor Biol 2011; 292:103-15. [PMID: 22001733 DOI: 10.1016/j.jtbi.2011.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 09/14/2011] [Accepted: 10/03/2011] [Indexed: 10/16/2022]
Abstract
Motivated by experimental and theoretical work on autonomous oscillations in yeast, we analyze ordinary differential equations models of large populations of cells with cell-cycle dependent feedback. We assume a particular type of feedback that we call responsive/signaling (RS), but do not specify a functional form of the feedback. We study the dynamics and emergent behavior of solutions, particularly temporal clustering and stability of clustered solutions. We establish the existence of certain periodic clustered solutions as well as "uniform" solutions and add to the evidence that cell-cycle dependent feedback robustly leads to cell-cycle clustering. We highlight the fundamental differences in dynamics between systems with negative and positive feedback. For positive feedback systems the most important mechanism seems to be the stability of individual isolated clusters. On the other hand we find that in negative feedback systems, clusters must interact with each other to reinforce coherence. We conclude from various details of the mathematical analysis that negative feedback is most consistent with observations in yeast experiments.
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Affiliation(s)
- Todd R Young
- Department of Mathematics, Ohio University, Athens, OH, USA.
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26
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Genetics and Regulation of Glycogen and Trehalose Metabolism in Saccharomyces cerevisiae. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/978-3-642-21467-7_2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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27
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Chang WQ, Wu XZ, Cheng AX, Zhang L, Ji M, Lou HX. Retigeric acid B exerts antifungal effect through enhanced reactive oxygen species and decreased cAMP. Biochim Biophys Acta Gen Subj 2011; 1810:569-76. [PMID: 21320573 DOI: 10.1016/j.bbagen.2011.02.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 01/30/2011] [Accepted: 02/02/2011] [Indexed: 11/28/2022]
Abstract
BACKGROUND Retigeric acid B (RAB), a triterpene acid isolated from Lobaria kurokawae exerts antifungal effect. The present study was designed to elucidate the underlying mechanisms by which RAB regulates the proliferation and cell death of Candida albicans. METHODS We measured the metabolic activity of C. albicans with WST1 Cell Proliferation and Cytotoxicity Assay Kit, analyzed the cell cycle by flow cytometry, visualized the ultrastructure by transmission electron microscopy (TEM) and investigated the apoptosis and necrosis induced by RAB using confocal microscopy. The reactive oxygen species (ROS) accumulation was determined by spectrophotometry, flow cytometry and fluorescent microscopy. The mtΔψ was detected using flow cytometry. And the levels of intracellular cAMP and ATP were measured with cAMP ELISA and ATP Assay Kits, respectively. RESULTS The proliferation of the yeasts was blocked in G(2)/M phase by a low dose of RAB treatment and in G(1) phase at high concentration. When cultured in phosphate buffered saline (PBS) deprived of energy source, yeasts displayed the phenotype of death caused by accumulated ROS, mtΔψ hyperpolarization and dramatic decrease in ATP level in the presence of high dose of RAB. GENERAL SIGNIFICANCE RAB inhibits the growth of C. albicans by stimulating ROS production and reducing intracellular cAMP. The ROS accumulation, mtΔψ hyperpolarization, ATP depletion and damaged plasma membrane integrity together mediate cell death of C. albicans induced by RAB. Our findings provide a novel molecular mechanism for exploring possible applications of lichen derived metabolites in fighting fungal infection in humans.
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Affiliation(s)
- Wen-Qiang Chang
- Department of Natural Product Chemistry, Shandong University, Jinan, People's Republic of China
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28
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Boczko EM, Stowers CC, Gedeon T, Young TR. ODE, RDE and SDE models of cell cycle dynamics and clustering in yeast. JOURNAL OF BIOLOGICAL DYNAMICS 2010; 4:328-45. [PMID: 20563236 PMCID: PMC2885793 DOI: 10.1080/17513750903288003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Biologists have long observed periodic-like oxygen consumption oscillations in yeast populations under certain conditions, and several unsatisfactory explanations for this phenomenon have been proposed. These ‘autonomous oscillations’ have often appeared with periods that are nearly integer divisors of the calculated doubling time of the culture. We hypothesize that these oscillations could be caused by a form of cell cycle synchronization that we call clustering. We develop some novel ordinary differential equation models of the cell cycle. For these models, and for random and stochastic perturbations, we give both rigorous proofs and simulations showing that both positive and negative growth rate feedback within the cell cycle are possible agents that can cause clustering of populations within the cell cycle. It occurs for a variety of models and for a broad selection of parameter values. These results suggest that the clustering phenomenon is robust and is likely to be observed in nature. Since there are necessarily an integer number of clusters, clustering would lead to periodic-like behaviour with periods that are nearly integer divisors of the period of the cell cycle. Related experiments have shown conclusively that cell cycle clustering occurs in some oscillating yeast cultures.
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Affiliation(s)
- Erik M. Boczko
- Department of Biomedical Informatics, Vanderbilt University
| | | | - Tomas Gedeon
- Department of Mathematics, Montana State University
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29
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Mechanisms of ethanol tolerance in Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2010; 87:829-45. [DOI: 10.1007/s00253-010-2594-3] [Citation(s) in RCA: 170] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/29/2010] [Accepted: 03/29/2010] [Indexed: 12/18/2022]
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30
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Lam CMC, Yeung PKK, Lee HC, Wong JTY. Cyclic ADP-ribose links metabolism to multiple fission in the dinoflagellate Crypthecodinium cohnii. Cell Calcium 2009; 45:346-57. [PMID: 19201464 DOI: 10.1016/j.ceca.2008.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 11/27/2008] [Accepted: 12/31/2008] [Indexed: 12/19/2022]
Abstract
Cellular metabolism is required for cell proliferation. However, the way in which metabolic signals are conveyed to cell cycle decisions is unclear. Cyclic ADP-ribose (cADPR), the NAD(+) metabolite, mobilizes calcium from calcium stores in many cells. We found that dinoflagellate cells with higher metabolic rate underwent multiple fission (MF), a division mode in which cells can exceed twice their sizes at G1. A temperature shift-down experiment suggested that MF involves a commitment point at late G1. In fast-growing cells, cADPR level peaked in G(1) and increased with increasing concentrations of glucose in the medium. Addition of glycolytic poison iodoacetate inhibited cell growth, reduced cADPR levels as well as the commitment of cell cycles in fast-growing cells. Commitment of MF cell cycles was induced by a cell permeant cADPR agonist, but blocked by a specific antagonist of cADPR-induced Ca(2+) release. Our results establish cADPR as a link between cellular metabolism and cell cycle control.
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Affiliation(s)
- Connie M C Lam
- Department of Biology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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31
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Tu BP, Mohler RE, Liu JC, Dombek KM, Young ET, Synovec RE, McKnight SL. Cyclic changes in metabolic state during the life of a yeast cell. Proc Natl Acad Sci U S A 2007; 104:16886-91. [PMID: 17940006 PMCID: PMC2040445 DOI: 10.1073/pnas.0708365104] [Citation(s) in RCA: 195] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Indexed: 11/18/2022] Open
Abstract
Budding yeast undergo robust oscillations in oxygen consumption during continuous growth in a nutrient-limited environment. Using liquid chromatography-mass spectrometry and comprehensive 2D gas chromatography-mass spectrometry-based metabolite profiling methods, we have determined that the intracellular concentrations of many metabolites change periodically as a function of these metabolic cycles. These results reveal the logic of cellular metabolism during different phases of the life of a yeast cell. They may further indicate that oscillation in the abundance of key metabolites might help control the temporal regulation of cellular processes and the establishment of a cycle. Such oscillations in metabolic state might occur during the course of other biological cycles.
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Affiliation(s)
- Benjamin P. Tu
- *Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038; and
| | | | - Jessica C. Liu
- *Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038; and
| | | | - Elton T. Young
- Biochemistry, University of Washington, Seattle, WA 98195
| | | | - Steven L. McKnight
- *Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038; and
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32
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Cazzaniga P, Pescini D, Besozzi D, Mauri G, Colombo S, Martegani E. Modeling and stochastic simulation of the Ras/cAMP/PKA pathway in the yeast Saccharomyces cerevisiae evidences a key regulatory function for intracellular guanine nucleotides pools. J Biotechnol 2007; 133:377-85. [PMID: 18023904 DOI: 10.1016/j.jbiotec.2007.09.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Revised: 09/06/2007] [Accepted: 09/29/2007] [Indexed: 11/26/2022]
Abstract
In the yeast Saccharomyces cerevisiae, the Ras/cAMP/PKA pathway is involved in the regulation of metabolism and cell cycle progression. The pathway is tightly regulated by several control mechanisms, as the feedback cycle ruled by the activity of phosphodiesterase. Here, we present a discrete mathematical model for the Ras/cAMP/PKA pathway that considers its principal cytoplasmic components and their mutual interactions. The tau-leaping algorithm is then used to perform stochastic simulations of the model. We investigate this system under various conditions, and we test how different values of several stochastic reaction constants affect the pathway behaviour. Finally, we show that the level of guanine nucleotides, GTP and GDP, could be relevant metabolic signals for the regulation of the whole pathway.
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Affiliation(s)
- Paolo Cazzaniga
- Università degli Studi di Milano-Bicocca, Dipartimento di Informatica, Sistemistica e Comunicazione, Viale Sarca 336, 20126 Milano, Italy
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33
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Transcriptome changes and cAMP oscillations in an archaeal cell cycle. BMC Cell Biol 2007; 8:21. [PMID: 17562013 PMCID: PMC1906763 DOI: 10.1186/1471-2121-8-21] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Accepted: 06/11/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The cell cycle of all organisms includes mass increase by a factor of two, replication of the genetic material, segregation of the genome to different parts of the cell, and cell division into two daughter cells. It is tightly regulated and typically includes cell cycle-specific oscillations of the levels of transcripts, proteins, protein modifications, and signaling molecules. Until now cell cycle-specific transcriptome changes have been described for four eukaryotic species ranging from yeast to human, but only for two prokaryotic species. Similarly, oscillations of small signaling molecules have been identified in very few eukaryotic species, but not in any prokaryote. RESULTS A synchronization procedure for the archaeon Halobacterium salinarum was optimized, so that nearly 100% of all cells divide in a time interval that is 1/4th of the generation time of exponentially growing cells. The method was used to characterize cell cycle-dependent transcriptome changes using a genome-wide DNA microarray. The transcript levels of 87 genes were found to be cell cycle-regulated, corresponding to 3% of all genes. They could be clustered into seven groups with different transcript level profiles. Cluster-specific sequence motifs were detected around the start of the genes that are predicted to be involved in cell cycle-specific transcriptional regulation. Notably, many cell cycle genes that have oscillating transcript levels in eukaryotes are not regulated on the transcriptional level in H. salinarum. Synchronized cultures were also used to identify putative small signaling molecules. H. salinarum was found to contain a basal cAMP concentration of 200 microM, considerably higher than that of yeast. The cAMP concentration is shortly induced directly prior to and after cell division, and thus cAMP probably is an important signal for cell cycle progression. CONCLUSION The analysis of cell cycle-specific transcriptome changes of H. salinarum allowed to identify a strategy of transcript level regulation that is different from all previously characterized species. The transcript levels of only 3% of all genes are regulated, a fraction that is considerably lower than has been reported for four eukaryotic species (6%-28%) and for the bacterium C. crescentus (19%). It was shown that cAMP is present in significant concentrations in an archaeon, and the phylogenetic profile of the adenylate cyclase indicates that this signaling molecule is widely distributed in archaea. The occurrence of cell cycle-dependent oscillations of the cAMP concentration in an archaeon and in several eukaryotic species indicates that cAMP level changes might be a phylogenetically old signal for cell cycle progression.
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34
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Singh A, Sharma S, Khuller GK. cAMP regulates vegetative growth and cell cycle in Candida albicans. Mol Cell Biochem 2007; 304:331-41. [PMID: 17557192 DOI: 10.1007/s11010-007-9516-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Accepted: 05/16/2007] [Indexed: 11/24/2022]
Abstract
We demonstrate here the regulatory role of cAMP in cell cycle of Candida albicans. cAMP was found to be a positive signal for growth and morphogenesis. Phosphodiesterase inhibitor aminophylline exhibited significant effects, i.e., increased growth, as well as induced morphogenesis. Atropine and trifluoperazine negatively regulated (inhibited) growth and did not induce morphogenesis. These changes were attributed to increase in cAMP levels and protein kinase A (PKA) activity in presence of aminophylline, while reduction was observed in atropine and trifluoperazine (TFP) grown cells. Alteration in cAMP signaling pathway affected the cell cycle progression in Candida albicans. Increased cAMP levels in aminophylline grown cells reduced the duration of cell cycle by inciting the cell cycle-specific expression of G1 cyclins (CLN1 and CLN2). However atropine and trifluoperazine delayed the expression of G1 cyclins and hence prolonged the cell cycle. Implication of cAMP signaling pathway in both the cell cycle and morphogenesis further opened the channels to explore the potential of this pathway to serve as a target for development of new antifungal drugs.
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Affiliation(s)
- Ajay Singh
- Department of Biochemistry, Post Graduate Institute of Medical Education & Research (PGIMER), Chandigarh 160012, India
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35
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Ramakrishnan V, Theodoris G, Bisson LF. Loss of IRA2 suppresses the growth defect on low glucose caused by the snf3 mutation in Saccharomyces cerevisiae. FEMS Yeast Res 2007; 7:67-77. [PMID: 17311585 DOI: 10.1111/j.1567-1364.2006.00159.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
SNF3 encodes a low-glucose sensor in Saccharomyces cerevisiae that regulates the expression of a subset of hexose transporter genes. Deletion of SNF3 prevents rapid adaptation to low glucose concentration. Novel spontaneous suppressor mutants of the snf3Delta phenotype were isolated. The mutations isolated fell into one of two groups: those that increase the expression of transporters regulated by Snf3p, and those that show no detectable effect on the regulation of these genes. The physiologic role of one mutation, rgg2 (restoration of growth on glucose), that did not affect HXT gene expression was assessed by transcriptome analysis. Genes involved in glycogen metabolism and cAMP pathways were affected by the rgg2 mutation, suggesting a cellular role as a regulatory protein. Attempts to clone the wild-type RGG2 allele were unsuccessful. The glycogen phenotype and genetic crossing allowed rgg2 to be identified as an allele of the IRA2 gene. Suppression of the snf3 mutant phenotype by deletion of IRA2 was confirmed. A possible mechanism of the suppression of the snf3 growth defect by mutation of ira2 is discussed.
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Affiliation(s)
- Vidhya Ramakrishnan
- Department of Viticulture and Enology, University of California, Davis, Davis, CA 95616-8749, USA
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36
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Murray DB, Lloyd D. A tuneable attractor underlies yeast respiratory dynamics. Biosystems 2006; 90:287-94. [PMID: 17074432 DOI: 10.1016/j.biosystems.2006.09.032] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 09/12/2006] [Accepted: 09/13/2006] [Indexed: 11/25/2022]
Abstract
Our understanding of the molecular structure and function in the budding yeast, Saccharomyces cerevisiae, surpasses that of all other eukaryotic cells. However, the fundamental properties of the complex processes and their control systems have been difficult to reconstruct from detailed dissection of their molecular components. Spontaneous oscillatory dynamics observed in self-synchronized continuous cultures is pervasive, involves much of the cellular network, and provides unique insights into integrative cell physiology. Here, in non-invasive experiments in vivo, we exploit these oscillatory dynamics to analyse the global timing of the cellular network to show the presence of a low-order chaotic component. Although robust to a wide range of environmental perturbations, the system responds and reacts to the imposition of harsh environmental conditions, in this case low pH, by dynamic re-organization of respiration, and this feeds upwards to affect cell division. These complex dynamics can be represented by a tuneable attractor that orchestrates cellular complexity and coherence to the environment.
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Affiliation(s)
- Douglas B Murray
- The Systems Biology Institute, 953 Shinanomachi Research Park, Keio University School of Medicine, 35 Shinanomachi, Shimjuku-ku, Tokyo 160-852, Japan.
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37
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Tu BP, McKnight SL. Metabolic cycles as an underlying basis of biological oscillations. Nat Rev Mol Cell Biol 2006; 7:696-701. [PMID: 16823381 DOI: 10.1038/nrm1980] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The evolutionary origins of periodic phenomena in biology, such as the circadian cycle, the hibernation cycle and the sleep-wake cycle, remain a mystery. We discuss the concept of temporal compartmentalization of metabolism that takes place during such cycles, and suggest that cyclic changes in a cell's metabolic state might be a fundamental driving force for such biological oscillations.
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Affiliation(s)
- Benjamin P Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390, USA.
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38
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Xu Z, Tsurugi K. A potential mechanism of energy-metabolism oscillation in an aerobic chemostat culture of the yeast Saccharomyces cerevisiae. FEBS J 2006; 273:1696-709. [PMID: 16623706 DOI: 10.1111/j.1742-4658.2006.05201.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The energy-metabolism oscillation in aerobic chemostat cultures of yeast is a periodic change of the respiro-fermentative and respiratory phase. In the respiro-fermentative phase, the NADH level was kept high and respiration was suppressed, and glucose was anabolized into trehalose and glycogen at a rate comparable to that of catabolism. On the transition to the respiratory phase, cAMP levels increased triggering the breakdown of storage carbohydrates and the increased influx of glucose into the glycolytic pathway activated production of glycerol and ethanol consuming NADH. The resulting increase in the NAD(+)/NADH ratio stimulated respiration in combination with a decrease in the level of ATP, which was consumed mainly in the formation of biomass accompanying budding, and the accumulated ethanol and glycerol were gradually degraded by respiration via NAD(+)-dependent oxidation to acetate and the respiratory phase ceased after the recovery of NADH and ATP levels. However, the mRNA levels of both synthetic and degradative enzymes of storage carbohydrates were increased around the early respiro-fermentative phase, when storage carbohydrates are being synthesized, suggesting that the synthetic enzymes were expressed directly as active forms while the degradative enzymes were activated late by cAMP. In summary, the energy-metabolism oscillation is basically regulated by a feedback loop of oxido-reductive reactions of energy metabolism mediated by metabolites like NADH and ATP, and is modulated by metabolism of storage carbohydrates in combination of post-translational and transcriptional regulation of the related enzymes. A potential mechanism of energy-metabolism oscillation is proposed.
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Affiliation(s)
- Zhaojun Xu
- Department of Biochemistry 2, University of Yamanashi, Faculty of Medicine, Tamaho, Japan
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39
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Abstract
Slowly growing budding yeast store carbohydrate, then liquidate it in late G1 phase of the cell cycle, superimposing a metabolic cycle on the cell cycle. This metabolic cycle may separate biochemically incompatible processes. Alternatively it may provide a burst of energy and material for commitment to the cell cycle. Stored carbohydrate could explain the size requirement for cells passing the Start point.
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Affiliation(s)
- Bruce Futcher
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794, USA.
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40
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Cazzaniga P, Pescini D, Besozzi D, Mauri G. Tau Leaping Stochastic Simulation Method in P Systems. MEMBRANE COMPUTING 2006. [DOI: 10.1007/11963516_19] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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41
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Kwok ACM, Wong JTY. Lipid Biosynthesis and its Coordination with Cell Cycle Progression. ACTA ACUST UNITED AC 2005; 46:1973-86. [PMID: 16239308 DOI: 10.1093/pcp/pci213] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The activation of cell cycle regulators at the G1/S boundary has been linked to the cellular protein synthesis rate. It is conceivable that regulatory mechanisms are required to allow cells to coordinate the synthesis of other macromolecules with cell cycle progression. The availability of highly synchronized cells and flow cytometric methods facilitates investigation of the dynamics of lipid synthesis in the entire cell cycle of the heterotrophic dinoflagellate Crypthecodinium cohnii. Flow cytograms of Nile red-stained cells revealed a stepwise increase in the polar lipid content and a continuous increase in neutral lipid content in the dinoflagellate cell cycle. A cell cycle delay at early G1, but not G2/M, was observed upon inhibition of lipid synthesis. However, lipid synthesis continued during cell cycle arrest at the G1/S transition. A cell cycle delay was not observed when inhibitors of cellulose synthesis and fatty acid synthesis were added after the late G1 phase of the cell cycle. This implicates a commitment point that monitors the synthesis of fatty acids at the late G1 phase of the dinoflagellate cell cycle. Reduction of the glucose concentration in the medium down-regulated the G1 cell size with a concomitant forward shift of the commitment point. Inhibition of lipid synthesis up-regulated cellulose synthesis and resulted in an increase in cellulosic contents, while an inhibition of cellulose synthesis had no effects on lipid synthesis. Fatty acid synthesis and cellulose synthesis are apparently coupled to the cell cycle via independent pathways.
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Affiliation(s)
- Alvin C M Kwok
- Department of Biology, Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong SAR, PR China
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42
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Glynn P. Neuropathy target esterase and phospholipid deacylation. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1736:87-93. [PMID: 16137924 DOI: 10.1016/j.bbalip.2005.08.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Revised: 08/01/2005] [Accepted: 08/01/2005] [Indexed: 10/25/2022]
Abstract
Certain organophosphates react with the active site serine residue of neuropathy target esterase (NTE) and cause axonal degeneration and paralysis. Cloning of NTE revealed the presence of homologues in eukaryotes from yeast to man and that the protein has both a catalytic and a regulatory domain. The latter contains sequences similar to the regulatory subunit of protein kinase A, suggesting that NTE may bind cyclic AMP. NTE is tethered via an amino-terminal transmembrane segment to the cytoplasmic face of the endoplasmic reticulum. Unlike wild-type yeast, mutants lacking NTE activity cannot deacylate CDP-choline pathway-synthesized phosphatidylcholine (PtdCho) to glycerophosphocholine (GroPCho) and fatty acids. In cultured mammalian cells, GroPCho levels rise and fall, respectively, in response to experimental over-expression, and inhibition, of NTE. A complex of PtdCho and Sec14p, a yeast phospholipid-binding protein, both inhibits the rate-limiting step in PtdCho synthesis and enhances deacylation of PtdCho by NTE. While yeast can maintain PtdCho homeostasis in the absence of NTE, certain post-mitotic metazoan cells may not be able to, and some NTE-null animals have deleterious phenotypes. NTE is not required for cell division in the early mammalian embryo or in larval and pupal forms of Drosophila, but is essential for placenta formation and survival of neurons in the adult. In vertebrates, the relative importance of NTE and calcium-independent phospholipase A2 for homeostatic PtdCho deacylation in particular cell types, possible interactions of NTE with Sec14p homologues and cyclic AMP, and whether deranged phospholipid metabolism underlies organophosphate-induced neuropathy are areas which require further investigation.
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Affiliation(s)
- Paul Glynn
- MRC Toxicology Unit, University of Leicester, Leicester LE1 9HN, UK.
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43
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Boer VM, Daran JM, Almering MJH, de Winde JH, Pronk JT. Contribution of the Saccharomyces cerevisiae transcriptional regulator Leu3p to physiology and gene expression in nitrogen- and carbon-limited chemostat cultures. FEMS Yeast Res 2005; 5:885-97. [PMID: 15949974 DOI: 10.1016/j.femsyr.2005.04.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Revised: 03/23/2005] [Accepted: 04/04/2005] [Indexed: 11/19/2022] Open
Abstract
Transcriptional regulation of branched-chain amino-acid metabolism in Saccharomyces cerevisiae involves two key regulator proteins, Leu3p and Gcn4p. Leu3p is a pathway-specific regulator, known to regulate six genes involved in branched-chain amino-acid metabolism and one gene in nitrogen assimilation. Gcn4p is a global regulator, involved in the general response to amino-acid and purine starvation. To investigate the contribution of Leu3p in regulation of gene expression, a leu3Delta strain was compared to an isogenic reference strain using DNA-microarray analysis. This comparison was performed for both glucose-grown/ammonium-limited and ethanol-limited/ammonium-excess chemostat cultures. In ethanol-limited cultures, absence of Leu3p led to reduced transcript levels of six of the seven established Leu3p target genes, but did not affect key physiological parameters. In ammonium-limited cultures, absence of Leu3p caused a drastic decrease in storage carbohydrate content. mRNA levels of genes involved in storage carbohydrate metabolism were also found reduced. Under N-limited conditions, the leu3Delta genotype elicited an amino-acid starvation response, leading to increased transcript levels of many amino-acid biosynthesis genes. By combining the transcriptome data with data from earlier studies that measured DNA binding of Leu3p both in vitro and in vivo, BAT1, GAT1 and OAC1 were identified as additional Leu3p-regulated genes. This study demonstrates that unravelling of transcriptional regulation networks should preferably include several cultivation conditions and requires a combination of experimental approaches.
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Affiliation(s)
- Viktor M Boer
- Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands
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44
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Oliva A, Rosebrock A, Ferrezuelo F, Pyne S, Chen H, Skiena S, Futcher B, Leatherwood J. The cell cycle-regulated genes of Schizosaccharomyces pombe. PLoS Biol 2005; 3:e225. [PMID: 15966770 PMCID: PMC1157095 DOI: 10.1371/journal.pbio.0030225] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Accepted: 04/21/2005] [Indexed: 12/12/2022] Open
Abstract
Many genes are regulated as an innate part of the eukaryotic cell cycle, and a complex transcriptional network helps enable the cyclic behavior of dividing cells. This transcriptional network has been studied in Saccharomyces cerevisiae (budding yeast) and elsewhere. To provide more perspective on these regulatory mechanisms, we have used microarrays to measure gene expression through the cell cycle of Schizosaccharomyces pombe (fission yeast). The 750 genes with the most significant oscillations were identified and analyzed. There were two broad waves of cell cycle transcription, one in early/mid G2 phase, and the other near the G2/M transition. The early/mid G2 wave included many genes involved in ribosome biogenesis, possibly explaining the cell cycle oscillation in protein synthesis in S. pombe. The G2/M wave included at least three distinctly regulated clusters of genes: one large cluster including mitosis, mitotic exit, and cell separation functions, one small cluster dedicated to DNA replication, and another small cluster dedicated to cytokinesis and division. S. pombe cell cycle genes have relatively long, complex promoters containing groups of multiple DNA sequence motifs, often of two, three, or more different kinds. Many of the genes, transcription factors, and regulatory mechanisms are conserved between S. pombe and S. cerevisiae. Finally, we found preliminary evidence for a nearly genome-wide oscillation in gene expression: 2,000 or more genes undergo slight oscillations in expression as a function of the cell cycle, although whether this is adaptive, or incidental to other events in the cell, such as chromatin condensation, we do not know. A comprehensive examination of gene expression throughout the cell cycle of fission yeast is compared with recent related studies to highlight robust transcriptional patterns.
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Affiliation(s)
- Anna Oliva
- 1 Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Adam Rosebrock
- 1 Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Francisco Ferrezuelo
- 1 Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Saumyadipta Pyne
- 2 Department of Computer Science, Stony Brook University, Stony Brook, New York, United States of America
| | - Haiying Chen
- 1 Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Steve Skiena
- 2 Department of Computer Science, Stony Brook University, Stony Brook, New York, United States of America
| | - Bruce Futcher
- 1 Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Janet Leatherwood
- 1 Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
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45
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Jules M, François J, Parrou JL. Autonomous oscillations in Saccharomyces cerevisiae during batch cultures on trehalose. FEBS J 2005; 272:1490-500. [PMID: 15752364 DOI: 10.1111/j.1742-4658.2005.04588.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report that autonomous oscillations, which usually happen in aerobic glucose-limited continuous cultures of yeast at low dilution rate, were also observed in trehalose discontinuous cultures of Saccharomyces cerevisiae. This unexpected oscillatory behaviour was therefore examined using fast Fourier transformation of online gas measurements. This robust mathematical analysis underlined the existence of two types of oscillation. The first was found to be linked to the cell cycle because (a) the periodicity corresponded to a fraction of the generation time and (b) the oscillations were accompanied by a transient increase in the budding index, mobilization of storage carbohydrates, and fermentative activity. Moreover, these oscillations occurred in a range of specific growth rates between 0.04 and 0.15 h(-1). All these criteria were consistent with the cell-cycle-related metabolic oscillations observed in the same range of growth rates in glucose-limited continuous cultures. The second type were short-period respiratory oscillations, independent of the specific growth rate. Both types of oscillation were found to take place consecutively and/or simultaneously during batch culture on trehalose. In addition, mobilization of intracellular trehalose emerged as a key parameter for the sustainability of these autonomous oscillations as they were no longer observed in a mutant defective in neutral trehalase activity. We propose that batch culture on trehalose may be an excellent device for further investigation of the molecular mechanisms that underlie autonomous oscillations in yeast.
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Affiliation(s)
- Matthieu Jules
- Centre de Bioingenierie Gilbert Durand, UMR-CNRS 5504, UMR-INRA 792, Institut National des Sciences Appliquées, Toulouse, France
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46
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Park JI, Grant CM, Dawes IW. The high-affinity cAMP phosphodiesterase of Saccharomyces cerevisiae is the major determinant of cAMP levels in stationary phase: involvement of different branches of the Ras-cyclic AMP pathway in stress responses. Biochem Biophys Res Commun 2005; 327:311-9. [PMID: 15629464 DOI: 10.1016/j.bbrc.2004.12.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2004] [Indexed: 10/26/2022]
Abstract
The Ras-cyclic AMP (cAMP) pathway is a major determinant of intrinsic stress resistance of the yeast Saccharomyces cerevisiae. Here, we isolated IRA2, encoding the Ras GTPase activator, as a global stress response gene. Subsequently, we studied the other negative regulators on the separate branch of the Ras-cAMP pathway, the low- or high-affinity cAMP phosphodiesterase encoded by PDE1 or PDE2, respectively. Deletion of PDE2, similar to ira2 deletion, rendered cells sensitive to freeze-thawing, peroxides, paraquat, cycloheximide, heavy metals, NaCl, heat, or cold shock. However, deletion of PDE1 did not affect stress tolerance, although it exacerbated stress sensitivity caused by the pde2 deletion, indicating that PDE1 can partly compensate for PDE2. Deletion of IRA2 uniquely led to high sensitivity to cumene hydroperoxide, suggesting that IRA2 may have a distinct role for the response to this stress. Stress sensitivity of yeast cells in general correlated with the basal level of cAMP. Interestingly, yeast cells lacking PDE2 maintained higher cAMP levels in stationary phase than exponential growth phase, suggesting that Pde2p is the major regulator of cAMP levels in stationary phase. Depletion of Ras activity could not effectively suppress stress sensitivity caused by lack of cAMP phosphodiesterases although it could suppress stress sensitivity caused by lack of IRA2, indicating that cAMP accumulation in stationary phase can be mediated by other signaling proteins in addition to Ras. Our study shows that control of cAMP basal levels is important for determining intrinsic stress tolerance of yeast, and that the cAMP level during stationary phase is a result of a dynamic balance between its rates of synthesis and degradation.
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Affiliation(s)
- Jong-In Park
- Ramaciotti Centre for Gene Function Analysis, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia
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47
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Wittmann C, Hans M, van Winden WA, Ras C, Heijnen JJ. Dynamics of intracellular metabolites of glycolysis and TCA cycle during cell-cycle-related oscillation inSaccharomyces cerevisiae. Biotechnol Bioeng 2005; 89:839-47. [PMID: 15690349 DOI: 10.1002/bit.20408] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In the present work LC-MS/MS was applied to measure the concentrations of intermediates of glycolysis and TCA cycle during autonomous, cell-cycle synchronized oscillations in aerobic, glucose-limited chemostat cultures of Saccharomyces cerevisiae. This study complements previously reported oscillations in carbon dioxide production rate, intracellular concentrations of trehalose and various free amino acids, and extracellular acetate and pyruvate in the same culture. Of the glycolytic intermediates, fructose 1,6-bisphosphate, 2- and 3-phosphoglycerate, and phosphoenolpyruvate show the most pronounced oscillatory behavior, the latter three compounds oscillating out of phase with the former. This agrees with previously observed metabolic control by phosphofructokinase and pyruvate kinase. Although individually not clearly oscillating, several intermediates of the TCA cycle, i.e., alpha-ketoglutarate, succinate, fumarate, and malate, exhibited increasing concentration during the cell cycle phase with high carbon flux through glycolysis and TCA cycle. The average mass action ratios of beta-phosphoglucomutase and fumarase agreed well with previously determined in vitro equilibrium constants. Minor differences resulted for phosphoglucose isomerase and enolase. Together with the observed close correlation of the pool sizes of the involved metabolites, this might indicate that, in vivo, these reactions are operating close to equilibrium, whereby care must be taken due to possible differences between in vivo and in vitro conditions. Combining the data with previously determined intracellular amino acid levels from the same culture, a few clear correlations between catabolism and anabolism could be identified: phosphoglycerate/serine and alpha-ketoglutarate/lysine exhibited correlated oscillatory behavior, albeit with different phase shifts. Oscillations in intracellular amino acids might therefore be, at least partly, following oscillations of their anabolic precursors.
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Affiliation(s)
- Christoph Wittmann
- Biochemical Engineering, Saarland University, POB 151150, 66123 Saarbrücken, Germany.
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Guillou V, Plourde-Owobi L, Parrou JL, Goma G, François J. Role of reserve carbohydrates in the growth dynamics of Saccharomyces cerevisiae. FEMS Yeast Res 2004; 4:773-87. [PMID: 15450184 DOI: 10.1016/j.femsyr.2004.05.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2004] [Revised: 05/03/2004] [Accepted: 05/04/2004] [Indexed: 11/17/2022] Open
Abstract
The purpose of this study was to explore the role of glycogen and trehalose in the ability of Saccharomyces cerevisiae to respond to a sudden rise of the carbon flux. To this end, aerobic glucose-limited continuous cultures were challenged with a sudden increase of the dilution rate from 0.05 to 0.15 h(-1). Under this condition, a rapid mobilization of glycogen and trehalose was observed which coincided with a transient burst of budding and a decrease of cell biomass. Experiments carried out with mutants defective in storage carbohydrates indicated a predominant role of glycogen in the adaptation to this perturbation. However, the real importance of trehalose in this response was veiled by the unexpected phenotypes harboured by the tps1 mutant, chosen for its inability to synthesize trehalose. First, the biomass yield of this mutant was 25% lower than that of the isogenic wild-type strain at dilution rate of 0.05 h(-1), and this difference was annulled when cultures were run at a higher dilution rate of 0.15 h(-1). Second, the tps1 mutant was more effective to sustain the dilution rate shift-up, apparently because it had a faster glycolytic rate and an apparent higher capacity to consume glucose with oxidative phosphorylation than the wild type. Consequently, a tps1gsy1gsy2 mutant was able to adapt to the dilution rate shift-up after a long delay, likely because the detrimental effects from the absence of glycogen was compensated for by the tps1 mutation. Third, a glg1Deltaglg2Delta strain, defective in glycogen synthesis because of the lack of the glycogen initiation protein, recovered glycogen accumulation upon further deletion of TPS1. This recovery, however, required glycogen synthase. Finally, we demonstrated that the rapid breakdown of reserve carbohydrates triggered by the shift-up is merely due to changes in the concentrations of hexose-6-phosphate and UDPglucose, which are the main metabolic effectors of the rate-limiting enzymes of glycogen and trehalose pathways.
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Affiliation(s)
- Vincent Guillou
- Centre de Bioingéniérie Gilbert Durand, Laboratoire Biotechnologie et Bioprocédés, UMR-CNRS 5504 & UMR-INRA 792, 31077 Toulouse Cedex 04, France
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Henson MA. Modeling the synchronization of yeast respiratory oscillations. J Theor Biol 2004; 231:443-58. [PMID: 15501474 DOI: 10.1016/j.jtbi.2004.07.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Revised: 06/30/2004] [Accepted: 07/12/2004] [Indexed: 10/26/2022]
Abstract
The budding yeast Saccharomyces cerevisiae exhibits autonomous oscillations when grown aerobically in continuous culture with ethanol as the primary carbon source. A single cell model that includes the sulfate assimilation and ethanol degradation pathways recently has been developed to study these respiratory oscillations. We utilize an extended version of this single cell model to construct large cell ensembles for investigation of a proposed synchronization mechanism involving hydrogen sulfide. Ensembles with as many as 10,000 cells are used to simulate population synchronization and to compute transient number distributions from asynchronous initial cell states. Random perturbations in intracellular kinetic parameters are introduced to study the synchronization of single cells with small variations in their unsynchronized oscillation periods. The cell population model is shown to be consistent with available experimental data and to provide insights into the regulatory mechanisms responsible for the synchronization of yeast metabolic oscillations.
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Affiliation(s)
- Michael A Henson
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003-9303, USA.
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Park JI, Collinson EJ, Grant CM, Dawes IW. Rom2p, the Rho1 GTP/GDP exchange factor of Saccharomyces cerevisiae, can mediate stress responses via the Ras-cAMP pathway. J Biol Chem 2004; 280:2529-35. [PMID: 15545276 DOI: 10.1074/jbc.m407900200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The Ras-cyclic AMP pathway is connected to other nutrient-regulated signaling pathways and mediates the global stress responses of Saccharomyces cerevisiae. Here, we show that Rom2p, the Rho1 GTP/GDP exchange factor, can mediate stress responses and cell growth via the Ras-cAMP pathways. ROM2 was isolated as a suppresser of heat and NaCl sensitivity caused by the lack of the Ras-GTPase activator Ira2p or of cAMP phosphodiesterases. Subsequent analysis of strains with a rom2 deletion showed that Rom2p is essential for resistance to a variety of stresses caused by freeze-thawing, oxidants, cycloheximide, NaCl, or cobalt ions. Stress sensitivity and the growth defect caused by the rom2 deletion could be suppressed by depleting Ras or protein kinase A (PKA) activity or by overexpressing the high affinity cAMP phosphodiesterase Pde2p. In addition, overexpression of ROM2 could not rescue cells lacking the regulatory subunit of PKA, indicating that the Ras-adenylate, cyclase-PKA cascade is essential for Rom2p-mediated stress responses and cell growth. Deletion of IRA2 exacerbated the freeze-thaw sensitivity and growth defect of the rom2 mutant, indicating that Rom2p signaling may control Ras independently of IRA2. Increases in cAMP levels were detected in the rom2 deletion mutants, and these were comparable with the effects of an ira2 mutation. The effects of the deletion of ROM2 on sensitivity to hydrogen peroxide, paraquat, and cobalt ions, but not to caffeine, were reduced when a constitutive allele of RHO1 was introduced on a single copy plasmid. However, the effects of the deletion of ROM2 on sensitivity to diamide and NaCl were exacerbated. Taken together, our data indicate that Rom2p can regulate PKA activity by controlling cAMP levels via the Ras-cAMP pathway and that for those stresses related to oxidative stress, this cross-talk is probably mediated via the Rho1p-activated MAPK pathway.
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Affiliation(s)
- Jong-In Park
- Ramaciotti Centre for Gene Function Analysis, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia
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