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Design of a MAPK signalling cascade balances energetic cost versus accuracy of information transmission. Nat Commun 2020; 11:3494. [PMID: 32661402 PMCID: PMC7359329 DOI: 10.1038/s41467-020-17276-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/22/2020] [Indexed: 01/30/2023] Open
Abstract
Cellular processes are inherently noisy, and the selection for accurate responses in presence of noise has likely shaped signalling networks. Here, we investigate the trade-off between accuracy of information transmission and its energetic cost for a mitogen-activated protein kinase (MAPK) signalling cascade. Our analysis of the pheromone response pathway of budding yeast suggests that dose-dependent induction of the negative transcriptional feedbacks in this network maximizes the information per unit energetic cost, rather than the information transmission capacity itself. We further demonstrate that futile cycling of MAPK phosphorylation and dephosphorylation has a measurable effect on growth fitness, with energy dissipation within the signalling cascade thus likely being subject to evolutionary selection. Considering optimization of accuracy versus the energetic cost of information processing, a concept well established in physics and engineering, may thus offer a general framework to understand the regulatory design of cellular signalling systems. Cellular signalling networks provide information to the cell, but the trade-off between accuracy of information transfer and energetic cost of doing so has not been assessed. Here, the authors investigate a MAPK signalling cascade in budding yeast and find that information is maximised per unit energetic cost.
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2
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Single-cell dynamics and variability of MAPK activity in a yeast differentiation pathway. Proc Natl Acad Sci U S A 2016; 113:E5896-E5905. [PMID: 27651485 DOI: 10.1073/pnas.1610081113] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In response to pheromones, yeast cells activate a MAPK pathway to direct processes important for mating, including gene induction, cell-cycle arrest, and polarized cell growth. Although a variety of assays have been able to elucidate signaling activities at multiple steps in the pathway, measurements of MAPK activity during the pheromone response have remained elusive, and our understanding of single-cell signaling behavior is incomplete. Using a yeast-optimized FRET-based mammalian Erk-activity reporter to monitor Fus3 and Kss1 activity in live yeast cells, we demonstrate that overall mating MAPK activity exhibits distinct temporal dynamics, rapid reversibility, and a graded dose dependence around the KD of the receptor, where phenotypic transitions occur. The complex dose response was found to be largely a consequence of two feedbacks involving cyclin-mediated scaffold phosphorylation and Fus3 autoregulation. Distinct cell cycle-dependent response patterns comprised a large portion of the cell-to-cell variability at each dose, constituting the major source of extrinsic noise in coupling activity to downstream gene-expression responses. Additionally, we found diverse spatial MAPK activity patterns to emerge over time in cells undergoing default, gradient, and true mating responses. Furthermore, ramping up and rapid loss of activity were closely associated with zygote formation in mating-cell pairs, supporting a role for elevated MAPK activity in successful cell fusion and morphogenic reorganization. Altogether, these findings present a detailed view of spatiotemporal MAPK activity during the pheromone response, elucidating its role in mediating complex long-term developmental fates in a unicellular differentiation system.
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Adjustable under-expression of yeast mating pathway proteins in Saccharomyces cerevisiae using a programmed ribosomal frameshift. Appl Microbiol Biotechnol 2016; 100:4997-5005. [PMID: 26837218 DOI: 10.1007/s00253-016-7335-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 01/13/2016] [Accepted: 01/17/2016] [Indexed: 10/22/2022]
Abstract
Experimental research in molecular biology frequently relies on the promotion or suppression of gene expression, an important tool in the study of its functions. Although yeast is among the most studied model systems with the ease of maintenance and manipulation, current experimental methods are mostly limited to gene deletion, suppression or overexpression of genes. Therefore, the ability to reduce protein expressions and then observing the effects would promote a better understanding of the exact functions and their interactions. Reducing protein expression is mainly limited by the difficulties associated with controlling the reduction level, and in some cases, the initial endogenous abundance is too low. For the under-expression to be useful as an experimental tool, repeatability and stability of reduced expression is important. We found that cis-elements in programmed -1 ribosomal frameshifting (-1RFS) of beet western yellow virus (BWYV) could be utilized to reduced protein expression in Saccharomyces cerevisiae. The two main advantages of using -1RFS are adjustable reduction rates and ease of use. To demonstrate the utility of this under-expression system, examples of reduced protein abundance were shown using yeast mating pathway components. The abundance of MAP kinase Fus3 was reduced to approximately 28-75 % of the wild-type value. Other MAP kinase mating pathway components, including Ste5, Ste11, and Ste7, were also under-expressed to verify that the -1RFS system works with different proteins. Furthermore, reduced Fus3 abundance altered the overall signal transduction outcome of the mating pathway, demonstrating the potential for further studies of signal transduction adjustment via under-expression.
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Large-Scale Analysis of Kinase Signaling in Yeast Pseudohyphal Development Identifies Regulation of Ribonucleoprotein Granules. PLoS Genet 2015; 11:e1005564. [PMID: 26447709 PMCID: PMC4598065 DOI: 10.1371/journal.pgen.1005564] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 09/10/2015] [Indexed: 01/10/2023] Open
Abstract
Yeast pseudohyphal filamentation is a stress-responsive growth transition relevant to processes required for virulence in pathogenic fungi. Pseudohyphal growth is controlled through a regulatory network encompassing conserved MAPK (Ste20p, Ste11p, Ste7p, Kss1p, and Fus3p), protein kinase A (Tpk2p), Elm1p, and Snf1p kinase pathways; however, the scope of these pathways is not fully understood. Here, we implemented quantitative phosphoproteomics to identify each of these signaling networks, generating a kinase-dead mutant in filamentous S. cerevisiae and surveying for differential phosphorylation. By this approach, we identified 439 phosphoproteins dependent upon pseudohyphal growth kinases. We report novel phosphorylation sites in 543 peptides, including phosphorylated residues in Ras2p and Flo8p required for wild-type filamentous growth. Phosphoproteins in these kinase signaling networks were enriched for ribonucleoprotein (RNP) granule components, and we observe co-localization of Kss1p, Fus3p, Ste20p, and Tpk2p with the RNP component Igo1p. These kinases localize in puncta with GFP-visualized mRNA, and KSS1 is required for wild-type levels of mRNA localization in RNPs. Kss1p pathway activity is reduced in lsm1Δ/Δ and pat1Δ/Δ strains, and these genes encoding P-body proteins are epistatic to STE7. The P-body protein Dhh1p is also required for hyphal development in Candida albicans. Collectively, this study presents a wealth of data identifying the yeast phosphoproteome in pseudohyphal growth and regulatory interrelationships between pseudohyphal growth kinases and RNPs. Eukaryotic cells affect precise changes in shape and growth in response to environmental and nutritional stress, enabling cell survival and wild-type function. The single-celled budding yeast provides a striking example, undergoing a set of changes under conditions of nitrogen or glucose limitation resulting in the formation of extended cellular chains or filaments. Related filamentous growth transitions are required for virulence in pathogenic fungi and have been studied extensively; however, the full scope of signaling underlying the filamentous growth transition remains to be determined. Here, we used a combination of genetics and proteomics to identify proteins that undergo phosphorylation dependent upon kinases required for filamentous growth. Within this protein set, we identified novel sites of phosphorylation in the yeast proteome and extensive phosphorylation of mRNA-protein complexes regulating mRNA decay and translation. The data indicate an interrelationship between filamentous growth and these ubiquitously conserved sites of RNA regulation: the RNA-protein complexes are required for the filamentous growth transition, and a well studied filamentous growth signaling kinase is required for wild-type numbers of RNA-protein complexes. This interdependence is previously unappreciated, highlighting an additional level of translational control underlying this complex growth transition.
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Vaga S, Bernardo-Faura M, Cokelaer T, Maiolica A, Barnes CA, Gillet LC, Hegemann B, van Drogen F, Sharifian H, Klipp E, Peter M, Saez-Rodriguez J, Aebersold R. Phosphoproteomic analyses reveal novel cross-modulation mechanisms between two signaling pathways in yeast. Mol Syst Biol 2014; 10:767. [PMID: 25492886 PMCID: PMC4300490 DOI: 10.15252/msb.20145112] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cells respond to environmental stimuli via specialized signaling pathways. Concurrent stimuli trigger multiple pathways that integrate information, predominantly via protein phosphorylation. Budding yeast responds to NaCl and pheromone via two mitogen-activated protein kinase cascades, the high osmolarity, and the mating pathways, respectively. To investigate signal integration between these pathways, we quantified the time-resolved phosphorylation site dynamics after pathway co-stimulation. Using shotgun mass spectrometry, we quantified 2,536 phosphopeptides across 36 conditions. Our data indicate that NaCl and pheromone affect phosphorylation events within both pathways, which thus affect each other at more levels than anticipated, allowing for information exchange and signal integration. We observed a pheromone-induced down-regulation of Hog1 phosphorylation due to Gpd1, Ste20, Ptp2, Pbs2, and Ptc1. Distinct Ste20 and Pbs2 phosphosites responded differently to the two stimuli, suggesting these proteins as key mediators of the information exchange. A set of logic models was then used to assess the role of measured phosphopeptides in the crosstalk. Our results show that the integration of the response to different stimuli requires complex interconnections between signaling pathways.
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Affiliation(s)
- Stefania Vaga
- Department of Biology, Institute of Molecular Systems Biology ETH Zürich, Zürich, Switzerland
| | - Marti Bernardo-Faura
- European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge, UK
| | - Thomas Cokelaer
- European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge, UK
| | - Alessio Maiolica
- Department of Biology, Institute of Molecular Systems Biology ETH Zürich, Zürich, Switzerland
| | - Christopher A Barnes
- Department of Biology, Institute of Molecular Systems Biology ETH Zürich, Zürich, Switzerland Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland
| | - Ludovic C Gillet
- Department of Biology, Institute of Molecular Systems Biology ETH Zürich, Zürich, Switzerland
| | - Björn Hegemann
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland
| | - Frank van Drogen
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland
| | - Hoda Sharifian
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland
| | - Edda Klipp
- Department of Biology, Theoretical Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Matthias Peter
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland
| | - Julio Saez-Rodriguez
- European Molecular Biology Laboratory (EMBL), European Bioinformatics Institute (EBI), Cambridge, UK
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology ETH Zürich, Zürich, Switzerland Faculty of Science, University of Zurich, Zurich, Switzerland
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Pincus D, Benjamin K, Burbulis I, Tsong AE, Resnekov O. Reagents for investigating MAPK signalling in model yeast species. Yeast 2010; 27:423-30. [PMID: 20162536 DOI: 10.1002/yea.1758] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Here we present a set of resources (bacterial expression plasmids and antibodies) for the interrogation of proteins involved in yeast MAPK signalling. We constructed bacterial protein expression plasmids for 25 proteins involved in MAPK signalling in budding yeast. From these constructs we expressed and purified proteins and generated rabbit polyclonal antibodies against 13 proteins in the pheromone MAPK pathway. We verified the specificity of the antibodies and employed them to follow pathway proteins in cells stimulated with pheromone. We show that these reagents can be used to detect pheromone-induced post-translational modifications and changes in the oligomeric state of pathway proteins. In addition to recognizing their target proteins in Saccharomyces cerevisiae, these antibodies allow the detection of predicted orthologues in the distant evolutionary relatives Kluyveromyces lactis and Schizosaccharomyces pombe. These antibodies are new tools for investigating MAPK signalling in model yeast species and may be useful for studying MAPK signalling in higher eukaryotes.
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Affiliation(s)
- David Pincus
- Molecular Sciences Institute, 2168 Shattuck Avenue, Berkeley, CA 94704, USA
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Lev S, Tal H, Rose MS, Horwitz BA. Signaling by the pathogenicity-related MAP kinase of Cochliobolus heterostrophus correlates with its local accumulation rather than phosphorylation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:1093-1103. [PMID: 19656044 DOI: 10.1094/mpmi-22-9-1093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Phosphorylated mitogen-activated protein kinases (MAPK) transmit signals by activation of their targets. The extent of signal transduction could depend on MAPK phosphorylation level, concentration, and subcellular localization. The pathogenicity MAPK Chk1 of the fungal corn pathogen Cochliobolus heterostrophus is required for central developmental functions, including appressoria formation, conidiation, melanization, virulence, and female fertility. We followed CHK1 transcript level, protein localization, quantity, phosphorylation, and expression of downstream genes during conidial germination on a surface inductive for appressoria formation and in suspension. The Chk1-GFP protein representing a translational fusion of Chk1 and GFP (green fluorescent protein) was very abundant in ungerminated conidia, accumulated in maturating appressoria and appressorial nuclei, but was uniformly distributed in suspension-grown hyphae. Expression of Chk1-dependent genes was upregulated in appressoria-forming hyphae but not in suspension. Despite Chk1 activation, there was no change in its phosphorylation and total protein quantity. Of all conditions tested, a temperature shift caused a decrease whereas hyperosmotic stress caused an increase in Chk1 phosphorylation. Activation of Chk1 during appressoria formation is apparently manifested by its local accumulation but not by significant changes in phosphorylation.
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Affiliation(s)
- Sophie Lev
- Department of Biology, Technion-Israel Institute of Technology, Haifa Israel
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Zaichick SV, Metodiev MV, Nelson SA, Durbrovskyi O, Draper E, Cooper JA, Stone DE. The mating-specific Galpha interacts with a kinesin-14 and regulates pheromone-induced nuclear migration in budding yeast. Mol Biol Cell 2009; 20:2820-30. [PMID: 19386762 DOI: 10.1091/mbc.e09-01-0069] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
As a budding yeast cell elongates toward its mating partner, cytoplasmic microtubules connect the nucleus to the cell cortex at the growth tip. The Kar3 kinesin-like motor protein is then thought to stimulate plus-end depolymerization of these microtubules, thus drawing the nucleus closer to the site where cell fusion and karyogamy will occur. Here, we show that pheromone stimulates a microtubule-independent interaction between Kar3 and the mating-specific Galpha protein Gpa1 and that Gpa1 affects both microtubule orientation and cortical contact. The membrane localization of Gpa1 was found to polarize early in the mating response, at about the same time that the microtubules begin to attach to the incipient growth site. In the absence of Gpa1, microtubules lose contact with the cortex upon shrinking and Kar3 is improperly localized, suggesting that Gpa1 is a cortical anchor for Kar3. We infer that Gpa1 serves as a positional determinant for Kar3-bound microtubule plus ends during mating.
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Affiliation(s)
- Sofia V Zaichick
- Laboratory for Molecular Biology, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
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Ydenberg CA, Rose MD. Antagonistic regulation of Fus2p nuclear localization by pheromone signaling and the cell cycle. ACTA ACUST UNITED AC 2009; 184:409-22. [PMID: 19188495 PMCID: PMC2646560 DOI: 10.1083/jcb.200809066] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
When yeast cells sense mating pheromone, they undergo a characteristic response involving changes in transcription, cell cycle arrest in early G1, and polarization along the pheromone gradient. Cells in G2/M respond to pheromone at the transcriptional level but do not polarize or mate until G1. Fus2p, a key regulator of cell fusion, localizes to the tip of the mating projection during pheromone-induced G1 arrest. Although Fus2p was expressed in G2/M cells after pheromone induction, it accumulated in the nucleus until after cell division. As cells arrested in G1, Fus2p was exported from the nucleus and localized to the nascent tip. Phosphorylation of Fus2p by Fus3p was required for Fus2p export; cyclin/Cdc28p-dependent inhibition of Fus3p during late G1 through S phase was sufficient to block exit. However, during G2/M, when Fus3p was activated by pheromone signaling, Cdc28p activity again blocked Fus2p export. Our results indicate a novel mechanism by which pheromone-induced proteins are regulated during the transition from mitosis to conjugation.
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Affiliation(s)
- Casey A Ydenberg
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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10
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Bharucha N, Ma J, Dobry CJ, Lawson SK, Yang Z, Kumar A. Analysis of the yeast kinome reveals a network of regulated protein localization during filamentous growth. Mol Biol Cell 2008; 19:2708-17. [PMID: 18417610 PMCID: PMC2441683 DOI: 10.1091/mbc.e07-11-1199] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2007] [Revised: 03/10/2008] [Accepted: 04/09/2008] [Indexed: 11/11/2022] Open
Abstract
The subcellular distribution of kinases and other signaling proteins is regulated in response to cellular cues; however, the extent of this regulation has not been investigated for any gene set in any organism. Here, we present a systematic analysis of protein kinases in the budding yeast, screening for differential localization during filamentous growth. Filamentous growth is an important stress response involving mitogen-activated protein kinase and cAMP-dependent protein kinase signaling modules, wherein yeast cells form interconnected and elongated chains. Because standard strains of yeast are nonfilamentous, we constructed a unique set of 125 kinase-yellow fluorescent protein chimeras in the filamentous Sigma1278b strain for this study. In total, we identified six cytoplasmic kinases (Bcy1p, Fus3p, Ksp1p, Kss1p, Sks1p, and Tpk2p) that localize predominantly to the nucleus during filamentous growth. These kinases form part of an interdependent, localization-based regulatory network: deletion of each individual kinase, or loss of kinase activity, disrupts the nuclear translocation of at least two other kinases. In particular, this study highlights a previously unknown function for the kinase Ksp1p, indicating the essentiality of its nuclear translocation during yeast filamentous growth. Thus, the localization of Ksp1p and the other kinases identified here is tightly controlled during filamentous growth, representing an overlooked regulatory component of this stress response.
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Affiliation(s)
- Nikë Bharucha
- Department of Molecular, Cellular, and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
| | - Jun Ma
- Department of Molecular, Cellular, and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
| | - Craig J. Dobry
- Department of Molecular, Cellular, and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
| | - Sarah K. Lawson
- Department of Molecular, Cellular, and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
| | - Zhifen Yang
- Department of Molecular, Cellular, and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
| | - Anuj Kumar
- Department of Molecular, Cellular, and Developmental Biology, and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216
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11
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Blackwell E, Kim HJN, Stone DE. The pheromone-induced nuclear accumulation of the Fus3 MAPK in yeast depends on its phosphorylation state and on Dig1 and Dig2. BMC Cell Biol 2007; 8:44. [PMID: 17963515 PMCID: PMC2219999 DOI: 10.1186/1471-2121-8-44] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 10/26/2007] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Like mammalian MAP kinases, the mating-specific Fus3 MAPK of yeast accumulates in the nuclei of stimulated cells. Because Fus3 does not appear to be subjected to active nucleo-cytoplasmic transport, it is not clear how its activation by mating pheromone effects the observed change in its localization. One possibility is that the activation of Fus3 changes its affinity for nuclear and cytoplasmic tethers. RESULTS Dig1, Dig2, and Ste12 are nuclear proteins that interact with Fus3. We found that the pheromone-induced nuclear accumulation of a Fus3-GFP reporter is reduced in cells lacking Dig1 or Dig2, whereas Fus3T180AY182A-GFP localization was unaffected by the absence of these proteins. This suggests that Dig1 and Dig2 contribute to the retention of phosphorylated Fus3 in the nucleus. Moreover, overexpression of Ste12 caused the hyper-accumulation of Fus3-GFP (but not Fus3T180AY182A-GFP) in the nuclei of pheromone-treated cells, suggesting that Ste12 also plays a role in the nuclear retention of phosphorylated Fus3, either by directly interacting with it or by transcribing genes whose protein products are Fus3 tethers. We have previously reported that overexpression of the Msg5 phosphatase inhibits the nuclear localization of Fus3. Here we show that this effect depends on the phosphatase activity of Msg5, and provide evidence that both nuclear and cytoplasmic Msg5 can affect the localization of Fus3. CONCLUSION Our data are consistent with a model in which the pheromone-induced phosphorylation of Fus3 increases its affinity for nuclear tethers, which contributes to its nuclear accumulation and is antagonized by Msg5.
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Affiliation(s)
- Ernest Blackwell
- Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - Hye-Jin N Kim
- Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, Illinois 60607, USA
| | - David E Stone
- Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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12
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Rubenstein EM, Schmidt MC. Mechanisms regulating the protein kinases of Saccharomyces cerevisiae. EUKARYOTIC CELL 2007; 6:571-83. [PMID: 17337635 PMCID: PMC1865659 DOI: 10.1128/ec.00026-07] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Eric M Rubenstein
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, W1247 Biomedical Science Tower, Pittsburgh, PA 15261, USA
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13
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Shao D, Zheng W, Qiu W, Ouyang Q, Tang C. Dynamic studies of scaffold-dependent mating pathway in yeast. Biophys J 2006; 91:3986-4001. [PMID: 16980360 PMCID: PMC1635675 DOI: 10.1529/biophysj.106.081661] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mating pathway in Saccharomyces cerevisiae is one of the best understood signal transduction pathways in eukaryotes. It transmits the mating signal from plasma membrane into the nucleus through the G-protein coupled receptor and the mitogen-activated protein kinase (MAPK) cascade. According to current understanding of the mating pathway, we construct a system of ordinary differential equations to describe the process. Our model is consistent with a wide range of experiments, indicating that it captures some main characteristics of the signal transduction along the pathway. Investigation with the model reveals that the shuttling of the scaffold protein and the dephosphorylation of kinases involved in the MAPK cascade cooperate to regulate the response upon pheromone induction and to help preserve the fidelity of the mating signaling. We explored factors affecting the dose-response curves of this pathway and found that both negative feedback and concentrations of the proteins involved in the MAPK cascade play crucial roles. Contrary to some other MAPK systems where signaling sensitivity is being amplified successively along the cascade, here the mating signal is transmitted through the cascade in an almost linear fashion.
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Affiliation(s)
- Danying Shao
- Center for Theoretical Biology, Peking University, Beijing, China
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14
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Schwartz MA, Madhani HD. Control of MAPK signaling specificity by a conserved residue in the MEK-binding domain of the yeast scaffold protein Ste5. Curr Genet 2006; 49:351-63. [PMID: 16463042 DOI: 10.1007/s00294-006-0061-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 01/17/2006] [Accepted: 01/18/2006] [Indexed: 11/30/2022]
Abstract
The yeast kinase scaffold Ste5 has been proposed to prevent unwanted cross-talk between the pheromone response pathway and other MAPK cascades. Protein fusion experiments have demonstrated that covalently tethering signaling components to each other or to Ste5 can determine the outcome of signaling. However, these do not fully test the role of scaffolds in signaling specificity, since fusing components precludes differential dissociation of subpopulations. We performed a targeted genetic screen on STE5 and repeatedly identified recessive mutations in a conserved residue, E756, in the Ste7/MEK-binding domain that caused erroneous activation of the filamentation MAPK pathway by pheromone signaling. Mutant cells exhibited a shift in the MAPK activation pattern such that the filamentation MAPK Kss1 was predominately activated in response to pheromone. Velocity sedimentation studies showed that the mutant scaffold was defective in binding to a phosphorylated subpopulation of Ste7. Our data suggest that increased dissociation of activated Ste7 kinase from the mutant scaffold may cause the observed shift in MAPK activation from Fus3 to Kss1 and the resulting loss of specificity. Cross-talk in ste5-E756G cells was due to both increased activation of Kss1 and reduced Fus3-dependent degradation of the filamentation pathway transcription factor Tec1. These studies demonstrate a role for an endogenous scaffold in signaling specificity.
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Affiliation(s)
- Monica A Schwartz
- Department of Biochemistry and Biophysics, University of California, San Francisco, 600 16th St, 94143-2200, USA
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15
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Bruno KS, Tenjo F, Li L, Hamer JE, Xu JR. Cellular localization and role of kinase activity of PMK1 in Magnaporthe grisea. EUKARYOTIC CELL 2005; 3:1525-32. [PMID: 15590826 PMCID: PMC539019 DOI: 10.1128/ec.3.6.1525-1532.2004] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A mitogen-activated protein (MAP) kinase gene, PMK1, is known to regulate appressorium formation and infectious hyphal growth in the rice blast fungus Magnaporthe grisea. In this study, we constructed a green fluorescent protein gene-PMK1 fusion (GFP-PMK1) to examine the expression and localization of PMK1 in M. grisea during infection-related morphogenesis. The GFP-PMK1 fusion encoded a functional protein that complemented the defect of the pmk1 deletion mutant in appressorium formation and plant infection. Although a weak GFP signal was detectable in vegetative hyphae, conidia, and germ tubes, the expression of GFP-Pmk1 was increased in appressoria and developing conidia. Nuclear localization of GFP-Pmk1 proteins was observed in a certain percentage of appressoria. A kinase-inactive allele and a nonphosphorylatable allele of PMK1 were constructed by site-directed mutagenesis. Expression of these mutant PMK1 alleles did not complement the pmk1 deletion mutant. These data confirm that kinase activity and activation of PMK1 by the upstream MAP kinase kinase are required for appressorium formation and plant infection in M. grisea. When overexpressed with the RP27 promoter in the wild-type strain, both the kinase-inactive and nonphosphorylatable PMK1 fusion proteins caused abnormal germ tube branching. Overexpression of these PMK1 mutant alleles may interfere with the function of native PMK1 during appressorium formation.
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Affiliation(s)
- Kenneth S Bruno
- Department of Botany and Plant Pathology, Lilly Hall, Purdue University, West Lafayette, IN 47907, USA
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16
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Abstract
The intracellular signal transduction pathway by which the yeast Saccharomyces cerevisiae responds to the presence of peptide mating pheromone in its surroundings is one of the best understood signaling pathways in eukaryotes, yet continues to generate new surprises and insights. In this review, we take a brief walk down the pathway, focusing on how the signal is transmitted from the cell-surface receptor-coupled G protein, via a MAP kinase cascade, to the nucleus.
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Affiliation(s)
- Lee Bardwell
- Department of Developmental and Cell Biology, 2208 Natural Sciences I, University of California, Irvine, CA 92697-2300, USA.
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17
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Abstract
The intracellular signal transduction pathway by which the yeast Saccharomyces cerevisiae responds to the presence of peptide mating pheromone in its surroundings is one of the best understood signaling pathways in eukaryotes, yet continues to generate new surprises and insights. In this review, we take a brief walk down the pathway, focusing on how the signal is transmitted from the cell-surface receptor-coupled G protein, via a MAP kinase cascade, to the nucleus.
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Affiliation(s)
- Lee Bardwell
- Department of Developmental and Cell Biology, 2208 Natural Sciences I, University of California, Irvine, CA 92697-2300, USA.
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18
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Andersson J, Simpson DM, Qi M, Wang Y, Elion EA. Differential input by Ste5 scaffold and Msg5 phosphatase route a MAPK cascade to multiple outcomes. EMBO J 2004; 23:2564-76. [PMID: 15192700 PMCID: PMC449765 DOI: 10.1038/sj.emboj.7600250] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2004] [Accepted: 05/04/2004] [Indexed: 11/08/2022] Open
Abstract
Pathway specificity is poorly understood for mitogen-activated protein kinase (MAPK) cascades that control different outputs in response to different stimuli. In yeast, it is not known how the same MAPK cascade activates Kss1 MAPK to promote invasive growth (IG) and proliferation, and both Fus3 and Kss1 MAPKs to promote mating. Previous work has suggested that the Kss1 MAPK cascade is activated independently of the mating G protein (Ste4)-scaffold (Ste5) system during IG. Here we demonstrate that Ste4 and Ste5 activate Kss1 during IG and in response to multiple stimuli including butanol. Ste5 activates Kss1 by generating a pool of active MAPKKK (Ste11), whereas additional scaffolding is needed to activate Fus3. Scaffold-independent activation of Kss1 can occur at multiple steps in the pathway, whereas Fus3 is strictly dependent on the scaffold. Pathway specificity is linked to Kss1 immunity to a MAPK phosphatase that constitutively inhibits basal activation of Fus3 and blocks activation of the mating pathway. These findings reveal the versatility of scaffolds and how a single MAPK cascade mediates different outputs.
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Affiliation(s)
- Jessica Andersson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - David M Simpson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Maosong Qi
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Yunmei Wang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Elaine A Elion
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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Wang Y, Elion EA. Nuclear export and plasma membrane recruitment of the Ste5 scaffold are coordinated with oligomerization and association with signal transduction components. Mol Biol Cell 2003; 14:2543-58. [PMID: 12808050 PMCID: PMC194901 DOI: 10.1091/mbc.e02-10-0699] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Ste5 scaffold activates an associated mitogen-activated protein kinase cascade by binding through its RING-H2 domain to a Gbetagamma dimer (Ste4/Ste18) at the plasma membrane in a recruitment event that requires prior nuclear shuttling of Ste5. Genetic evidence suggests that Ste5 must oligomerize to function, but its impact on Ste5 function and localization is unknown. Herein, we show that oligomerization affects Ste5 activity and localization. The majority of Ste5 is monomeric, suggesting that oligomerization is tightly regulated. Increasing the pool of Ste5 oligomers increases association with Ste11. Remarkably, Ste5 oligomers are also more efficiently exported from the nucleus, retained in the cytoplasm by Ste11 and better recruited to the plasma membrane, resulting in constitutive activation of the mating mitogen-activated protein kinase cascade. Coprecipitation tests show that the RING-H2 domain is the key determinant of oligomerization. Mutational analysis suggests that the leucine-rich domain limits the accessibility of the RING-H2 domain and inhibits export and recruitment in addition to promoting Ste11 association and activation. Our results suggest that the major form of Ste5 is an inactive monomer with an inaccessible RING-H2 domain and Ste11 binding site, whereas the active form is an oligomer that is more efficiently exported and recruited and has a more accessible RING-H2 domain and Ste11 binding site.
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Affiliation(s)
- Yunmei Wang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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20
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Blackwell E, Halatek IM, Kim HJN, Ellicott AT, Obukhov AA, Stone DE. Effect of the pheromone-responsive G(alpha) and phosphatase proteins of Saccharomyces cerevisiae on the subcellular localization of the Fus3 mitogen-activated protein kinase. Mol Cell Biol 2003; 23:1135-50. [PMID: 12556475 PMCID: PMC141143 DOI: 10.1128/mcb.23.4.1135-1150.2003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mating-specific G(alpha) protein of Saccharomyces cerevisiae, Gpa1, stimulates adaptation to pheromone by a mechanism independent of G(beta gamma) sequestration. Genetic evidence suggests that Gpa1 targets the Fus3 mitogen-activated protein kinase, and it has recently been shown that the two proteins interact in cells responding to pheromone. To test the possibility that Gpa1 downregulates the mating signal by affecting the localization of Fus3, we created a Fus3-green fluorescent protein (GFP) fusion protein. In vegetative cells, Fus3-GFP was found in both the cytoplasm and the nucleus. Pheromone stimulated a measurable increase in the ratio of nuclear to cytoplasmic Fus3-GFP. In contrast, the relative level of nuclear Fus3-GFP decreased as cells recovered from pheromone arrest and did not increase when cells adapted to chronic stimulus were challenged again. Accumulation of Fus3-GFP in the nuclei of stimulated cells was also inhibited by overexpression of either wild-type Gpa1, the E364K hyperadaptive mutant form of Gpa1, or the Msg5 dually specific phosphatase. The effects of Gpa1 and Msg5 on Fus3 are partially interdependent. In a genetic screen for adaptive defective mutants, a nonsense allele of the nucleocytoplasmic transport receptor, Kap104, was identified. Truncation of the Kap104 cargo-binding domain blocked the effect of both Gpa1(E364K) and Msg5 on Fus3-GFP localization. Based on these results, we propose that Gpa1 and Msg5 work in concert to downregulate the mating signal and that they do so by inhibiting the pheromone-induced increase of Fus3 in the nucleus. Kap104 is required for the G(alpha)/phosphatase-mediated effect on Fus3 localization.
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Affiliation(s)
- Ernest Blackwell
- Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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21
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Somsen OJG, Siderius M, Bauer FF, Snoep JL, Westerhoff HV. Selectivity in overlapping MAP kinase cascades. J Theor Biol 2002; 218:343-54. [PMID: 12381435 DOI: 10.1006/jtbi.2002.3082] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Some protein kinases operate in more than one mitogen-activated protein-kinase (MAPK) cascade. We here address the question whether specificity of the cascades necessitates physical sequestration of these "promiscuous" kinases (e.g. by binding to scaffolds). A model is constructed, in which two MAPK cascades depend on a single MAP-kinase kinase that is not sequestered in two subpopulations. We show that in this model selective signal transduction is possible provided that there is an additional interaction at the MAP-kinase level, there is no simultaneous activation of more than one response by either signal. We discuss a number of additional interactions that can generate the selectivity, as well as some kinetic features by which this mechanism may be recognized experimentally.
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Affiliation(s)
- Oscar J G Somsen
- Department of Molecular Cell Physiology, Free University Amsterdam, De Boelelaan 1087, NL-1081 HV, Amsterdam, The Netherlands
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22
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Metodiev MV, Matheos D, Rose MD, Stone DE. Regulation of MAPK function by direct interaction with the mating-specific Galpha in yeast. Science 2002; 296:1483-6. [PMID: 12029138 DOI: 10.1126/science.1070540] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The mating response of the budding yeast Saccharomyces cerevisiae is mediated by a prototypical heterotrimeric GTP-binding protein (G protein) and mitogen-activated protein kinase (MAPK) cascade. Although signal transmission by such pathways has been modeled in detail, postreceptor down-regulation is less well understood. The pheromone-responsive G protein alpha subunit (Galpha) of yeast down-regulates the mating signal, but its targets are unknown. We have found that Galpha binds directly to the mating-specific MAPK in yeast cells responding to pheromone. This interaction contributes both to modulation of the mating signal and to the chemotropic response, and it demonstrates direct communication between the top and bottom of a Galpha-MAPK pathway.
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Affiliation(s)
- Metodi V Metodiev
- Department of Biological Sciences, Laboratory for Molecular Biology, University of Illinois at Chicago, 900 South Ashland Avenue (M/C 567), Chicago, IL 60607, USA
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23
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Abstract
All cells have the capacity to respond to chemical and sensory stimuli. Central to many such signaling pathways is the heterotrimeric G protein, which transmits a signal from cell surface receptors to intracellular effectors. Recent studies using the yeast Saccharomyces cerevisiae have produced important advances in our understanding of G protein activation and inactivation. This review focuses on the mechanisms by which G proteins transmit a signal from peptide pheromone receptors to the mating response in yeast and how mechanisms elucidated in yeast can provide insights to signaling events in more complex organisms.
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Affiliation(s)
- Henrik G Dohlman
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
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Dohlman HG, Thorner JW. Regulation of G protein-initiated signal transduction in yeast: paradigms and principles. Annu Rev Biochem 2002; 70:703-54. [PMID: 11395421 DOI: 10.1146/annurev.biochem.70.1.703] [Citation(s) in RCA: 366] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
All cells have the capacity to evoke appropriate and measured responses to signal molecules (such as peptide hormones), environmental changes, and other external stimuli. Tremendous progress has been made in identifying the proteins that mediate cellular response to such signals and in elucidating how events at the cell surface are linked to subsequent biochemical changes in the cytoplasm and nucleus. An emerging area of investigation concerns how signaling components are assembled and regulated (both spatially and temporally), so as to control properly the specificity and intensity of a given signaling pathway. A related question under intensive study is how the action of an individual signaling pathway is integrated with (or insulated from) other pathways to constitute larger networks that control overall cell behavior appropriately. This review describes the signal transduction pathway used by budding yeast (Saccharomyces cerevisiae) to respond to its peptide mating pheromones. This pathway is comprised by receptors, a heterotrimeric G protein, and a protein kinase cascade all remarkably similar to counterparts in multicellular organisms. The primary focus of this review, however, is recent advances that have been made, using primarily genetic methods, in identifying molecules responsible for regulation of the action of the components of this signaling pathway. Just as many of the constituent proteins of this pathway and their interrelationships were first identified in yeast, the functions of some of these regulators have clearly been conserved in metazoans, and others will likely serve as additional models for molecules that carry out analogous roles in higher organisms.
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Affiliation(s)
- H G Dohlman
- Department of Pharmacology, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536-0812, USA.
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25
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van Drogen F, Stucke VM, Jorritsma G, Peter M. MAP kinase dynamics in response to pheromones in budding yeast. Nat Cell Biol 2001; 3:1051-9. [PMID: 11781566 DOI: 10.1038/ncb1201-1051] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although scaffolding is a major regulator of mitogen-activated protein kinase (MAPK) pathways, scaffolding proteins are poorly understood. During yeast mating, MAPK Fus3p is phosphorylated by MAPKK Ste7p, which is activated by MAPKKK Ste11p. This MAPK module interacts with the scaffold molecule Ste5p. Here we show that Ste11p and Ste7p were predominantly cytoplasmic proteins, while Ste5p and Fus3p were found in the nucleus and the cytoplasm. Ste5p, Ste7p and Fus3p also localized to tips of mating projections in pheromone-treated cells. Using fluorescence recovery after photobleaching (FRAP), we demonstrate that Fus3p rapidly shuttles between the nucleus and the cytoplasm independently of pheromones, Fus3p phosphorylation and Ste5p. Membrane-bound Ste5p can specifically recruit Fus3p and Ste7p to the cell cortex. Ste5p remains stably bound at the plasma membrane, unlike activated Fus3p, which dissociates from Ste5p and translocates to the nucleus.
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Affiliation(s)
- F van Drogen
- Swiss Institute for Experimental Cancer Research (ISREC), Chemin des Boveresses 155, 1066 Epalinges/VD, Switzerland
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26
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Abstract
An emerging theme of mitogen-activated protein kinase (MAPK) cascades is that they form molecular assemblies within cells; the spatial organization of which is provided by scaffold proteins. Yeast Ste5p was the first MAPK cascade scaffold to be described. Early work demonstrated that Ste5p selectively tethers the MAPKKK, MAPKK and MAPK of the yeast mating pathway and is essential for efficient activation of the MAPK by the pheromone stimulus. Recent work indicates that Ste5p is not a passive scaffold but plays a direct role in the activation of the MAPKKK by a heterotrimeric G protein and PAK-type kinase. This activation event requires the formation of an active Ste5p oligomer and proper recruitment of Ste5p to a Gβγ dimer at the submembrane of the cell cortex, which suggests that Ste5p forms a stable Ste5p signalosome linked to a G protein. Additional studies underscore the importance of regulated localization of Ste5p to the plasma membrane and have revealed nuclear shuttling as a regulatory device that controls the access of Ste5p to the plasma membrane. A model that links Ste5p oligomerization with stable membrane recruitment is presented. In this model, pathway activation is coordinated with the conversion of a less active closed form of Ste5 containing a protected RING-H2 domain into an active Ste5p dimer that can bind to Gβγ and form a multimeric scaffold lattice upon which the MAPK cascade can assemble.
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Affiliation(s)
- E A Elion
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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Pearson G, Robinson F, Beers Gibson T, Xu BE, Karandikar M, Berman K, Cobb MH. Mitogen-activated protein (MAP) kinase pathways: regulation and physiological functions. Endocr Rev 2001; 22:153-83. [PMID: 11294822 DOI: 10.1210/edrv.22.2.0428] [Citation(s) in RCA: 1318] [Impact Index Per Article: 57.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitogen-activated protein (MAP) kinases comprise a family of ubiquitous proline-directed, protein-serine/threonine kinases, which participate in signal transduction pathways that control intracellular events including acute responses to hormones and major developmental changes in organisms. MAP kinases lie in protein kinase cascades. This review discusses the regulation and functions of mammalian MAP kinases. Nonenzymatic mechanisms that impact MAP kinase functions and findings from gene disruption studies are highlighted. Particular emphasis is on ERK1/2.
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Affiliation(s)
- G Pearson
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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28
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Abstract
The machinery that mediates membrane fusion during yeast mating has remained elusive. But now a post-genomics approach has provided a powerful wedge into this difficult problem: a pheromone-induced multimembrane spanning protein has been identified as a key part of the mating machine.
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Affiliation(s)
- J M White
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA.
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29
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Abstract
Saccharomyces cerevisiae responds to mating pheromones by activating a receptor-G-protein-coupled mitogen-activated protein kinase (MAPK) cascade that is also used by other signaling pathways. The activation of the MAPK cascade may involve conformational changes through prebound receptor and heterotrimeric G-protein. G beta may then recruit Cdc42-bound MAPKKKK Ste20 to MAPKKK Ste11 through direct interactions with Ste20 and the Ste5 scaffold. Ste20 activates Ste11 by derepressing an autoinhibitory domain. An underlying nuclear shuttling machinery may be required for proper recruitment of Ste5 to G beta. Subsequent polarized growth is mediated by a similar mechanism involving Far1, which binds G beta in addition to Cdc24 and Bem1. Far1 and Cdc24 also undergo nuclear shuttling and the nuclear pool of Far1 may temporally regulate access of Cdc24 to the cell cortex.
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Affiliation(s)
- E A Elion
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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30
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Abstract
MAP kinases are a family of protein kinases that are ubiquitously expressed and play roles in most signal transduction pathways. They are activated within protein kinase cascades consisting of at least three kinases acting in series. In many, if not all cases, the three-kinase cascade, conveniently referred to as a MAP kinase module, is organized on scaffolds with a variety of forms and functions. This review discusses similarities and differences in scaffolding proteins and mechanisms in yeast, flies, worms and mammals.
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Affiliation(s)
- M Karandikar
- Department of Pharmacology, Southwestern Medical Center, Dallas, TX 75235-9041, USA
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31
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Choi YJ, Kim SH, Park KS, Choi KY. Differential transmission of G1 cell cycle arrest and mating signals bySaccharomyces cerevisiaeSte5 mutants in the pheromone pathway. Biochem Cell Biol 1999. [DOI: 10.1139/o99-054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Saccharomyces cerevisiae Ste5 is a scaffold protein that recruits many pheromone signaling molecules to sequester the pheromone pathway from other homologous mitogen-activated protein kinase pathways. G1 cell cycle arrest and mating are two different physiological consequences of pheromone signal transduction and Ste5 is required for both processes. However, the roles of Ste5 in G1 arrest and mating are not fully understood. To understand the roles of Ste5 better, we isolated 150 G1 cell cycle arrest defective STE5 mutants by chemical mutagenesis of the gene. Here, we found that two G1 cell cycle arrest defective STE5 mutants (ste5MD248Vand ste5delta-776) retained mating capacity. When overproduced in a wild-type strain, several ste5 mutants also showed different dominant phenotypes for G1 arrest and mating. Isolation and characterization of the mutants suggested separable roles of Ste5 in G1 arrest and mating of S. cerevisiae. In addition, the roles of Asp-248 and Tyr-421, which are important for pheromone signal transduction were further characterized by site-directed mutagenesis studies.Key words: Ste5, Saccharomyces cerevisiae, signal transduction, mating, G1 cell cycle arrest.
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32
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Mahanty SK, Wang Y, Farley FW, Elion EA. Nuclear shuttling of yeast scaffold Ste5 is required for its recruitment to the plasma membrane and activation of the mating MAPK cascade. Cell 1999; 98:501-12. [PMID: 10481914 DOI: 10.1016/s0092-8674(00)81978-9] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Localization of Ste5 to GP at the plasma membrane is essential for transmission of the pheromone signal to associated MAP kinase cascade enzymes. Here, we show that this crucial localization requires prior shuttling of Ste5 through the nucleus. Ste5 shuttles through the nucleus constitutively during vegetative growth. Pheromone enhances nuclear export of Ste5, and this pool translocates vectorially to the cell periphery. Remarkably, Ste5 that cannot transit the nucleus is unable to localize at the periphery and activate the pathway, while Ste5 with enhanced transit through the nucleus has enhanced ability to localize to the periphery and activate the pathway. This novel regulatory scheme may ensure that cytoplasmic Ste5 does not activate downstream kinases in the absence of pheromone and could be applicable to other membrane-recruited signaling proteins.
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Affiliation(s)
- S K Mahanty
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Farley FW, Satterberg B, Goldsmith EJ, Elion EA. Relative dependence of different outputs of the Saccharomyces cerevisiae pheromone response pathway on the MAP kinase Fus3p. Genetics 1999; 151:1425-44. [PMID: 10101167 PMCID: PMC1460551 DOI: 10.1093/genetics/151.4.1425] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fus3p and Kss1p act at the end of a conserved signaling cascade that mediates numerous cellular responses for mating. To determine the role of Fus3p in different outputs, we isolated and characterized a series of partial-function fus3 point mutants for their ability to phosphorylate a substrate (Ste7p), activate Ste12p, undergo G1 arrest, form shmoos, select partners, mate, and recover. All the mutations lie in residues that are conserved among MAP kinases and are predicted to affect either enzyme activity or binding to Ste7p or substrates. The data argue that Fus3p regulates the various outputs assayed through the phosphorylation of multiple substrates. Different levels of Fus3p function are required for individual outputs, with the most function required for shmoo formation, the terminal output. The ability of Fus3p to promote shmoo formation strongly correlates with its ability to promote G1 arrest, suggesting that the two events are coupled. Fus3p promotes recovery through a mechanism that is distinct from its ability to promote G1 arrest and may involve a mechanism that does not require kinase activity. Moreover, catalytically inactive Fus3p inhibits the ability of active Fus3p to activate Ste12p and hastens recovery without blocking G1 arrest or shmoo formation. These results raise the possibility that in the absence of sustained activation of Fus3p, catalytically inactive Fus3p blocks further differentiation by restoring mitotic growth. Finally, suppression analysis argues that Kss1p contributes to the overall pheromone response in a wild-type strain, but that Fus3p is the critical kinase for all of the outputs tested.
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Affiliation(s)
- F W Farley
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
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