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Nelson B, Parsons AB, Evangelista M, Schaefer K, Kennedy K, Ritchie S, Petryshen TL, Boone C. Fus1p interacts with components of the Hog1p mitogen-activated protein kinase and Cdc42p morphogenesis signaling pathways to control cell fusion during yeast mating. Genetics 2004; 166:67-77. [PMID: 15020407 PMCID: PMC1470681 DOI: 10.1534/genetics.166.1.67] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell fusion in the budding yeast Saccharomyces cerevisiae is a temporally and spatially regulated process that involves degradation of the septum, which is composed of cell wall material, and occurs between conjugating cells within a prezygote, followed by plasma membrane fusion. The plasma membrane protein Fus1p is known to be required for septum degradation during cell fusion, yet its role at the molecular level is not understood. We identified Sho1p, an osmosensor for the HOG MAPK pathway, as a binding partner for Fus1 in a two-hybrid screen. The Sho1p-Fus1p interaction occurs directly and is mediated through the Sho1p-SH3 domain and a proline-rich peptide ligand on the Fus1p COOH-terminal cytoplasmic region. The cell fusion defect associated with fus1Delta mutants is suppressed by a sho1Delta deletion allele, suggesting that Fus1p negatively regulates Sho1p signaling to ensure efficient cell fusion. A two-hybrid matrix containing fusion proteins and pheromone response pathway signaling molecules reveals that Fus1p may participate in a complex network of interactions. In particular, the Fus1p cytoplasmic domain interacts with Chs5p, a protein required for secretion of specialized Chs3p-containing vesicles during bud development, and chs5Delta mutants were defective in cell surface localization of Fus1p. The Fus1p cytoplasmic domain also interacts with the activated GTP-bound form of Cdc42p and the Fus1p-SH3 domain interacts with Bni1p, a yeast formin that participates in cell fusion and controls the assembly of actin cables to polarize secretion in response to Cdc42p signaling. Taken together, our results suggest that Fus1p acts as a scaffold for the assembly of a cell surface complex involved in polarized secretion of septum-degrading enzymes and inhibition of HOG pathway signaling to promote cell fusion.
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Affiliation(s)
- Bryce Nelson
- Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada
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2
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Matheos D, Metodiev M, Muller E, Stone D, Rose MD. Pheromone-induced polarization is dependent on the Fus3p MAPK acting through the formin Bni1p. ACTA ACUST UNITED AC 2004; 165:99-109. [PMID: 15067022 PMCID: PMC2172092 DOI: 10.1083/jcb.200309089] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
During mating, budding yeast cells reorient growth toward the highest concentration of pheromone. Bni1p, a formin homologue, is required for this polarized growth by facilitating cortical actin cable assembly. Fus3p, a pheromone-activated MAP kinase, is required for pheromone signaling and cell fusion. We show that Fus3p phosphorylates Bni1p in vitro, and phosphorylation of Bni1p in vivo during the pheromone response is dependent on Fus3p. fus3 mutants exhibited multiple phenotypes similar to bni1 mutants, including defects in actin and cell polarization, as well as Kar9p and cytoplasmic microtubule localization. Disruption of the interaction between Fus3p and the receptor-associated Gα subunit caused similar mutant phenotypes. After pheromone treatment, Bni1p-GFP and Spa2p failed to localize to the cortex of fus3 mutants, and cell wall growth became completely unpolarized. Bni1p overexpression suppressed the actin assembly, cell polarization, and cell fusion defects. These data suggest a model wherein activated Fus3p is recruited back to the cortex, where it activates Bni1p to promote polarization and cell fusion.
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Affiliation(s)
- Dina Matheos
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, USA
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3
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Ren B, Robert F, Wyrick JJ, Aparicio O, Jennings EG, Simon I, Zeitlinger J, Schreiber J, Hannett N, Kanin E, Volkert TL, Wilson CJ, Bell SP, Young RA. Genome-wide location and function of DNA binding proteins. Science 2000; 290:2306-9. [PMID: 11125145 DOI: 10.1126/science.290.5500.2306] [Citation(s) in RCA: 1390] [Impact Index Per Article: 57.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Understanding how DNA binding proteins control global gene expression and chromosomal maintenance requires knowledge of the chromosomal locations at which these proteins function in vivo. We developed a microarray method that reveals the genome-wide location of DNA-bound proteins and used this method to monitor binding of gene-specific transcription activators in yeast. A combination of location and expression profiles was used to identify genes whose expression is directly controlled by Gal4 and Ste12 as cells respond to changes in carbon source and mating pheromone, respectively. The results identify pathways that are coordinately regulated by each of the two activators and reveal previously unknown functions for Gal4 and Ste12. Genome-wide location analysis will facilitate investigation of gene regulatory networks, gene function, and genome maintenance.
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Affiliation(s)
- B Ren
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
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4
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Fujimura H. The immunosuppressive drug leflunomide affects mating-pheromone response and sporulation by different mechanisms in Saccharomyces cerevisiae. FEMS Microbiol Lett 2000; 191:57-60. [PMID: 11004400 DOI: 10.1111/j.1574-6968.2000.tb09319.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Leflunomide (LFM) is a novel anti-inflammatory and immunosuppressive drug, and inhibits the growth of cytokine-stimulated lymphoid cells in vitro. The effect of LFM on haploid and diploid cells of Saccharomyces cerevisiae was investigated to elucidate the molecular mechanism of action of the drug. Using a halo assay, LFM was shown to enhance the cell cycle arrest of haploid cells induced by mating pheromone alpha-factor. LFM also inhibited sporulation of diploid cells completely. S. cerevisiae genes which were cloned to suppress the anti-proliferative effect when present in increased copy number were introduced and examined for their activity to suppress the effect of LFM. Out of them, MLF4/SSH4, was found to suppress the sporulation-inhibitory effect of LFM. However, MLF4 failed to suppress the enhancing effect of LFM on pheromone response. Thus, LFM is suggested to act on haploid and diploid cells by different mechanisms.
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Affiliation(s)
- H Fujimura
- Laboratory of Advanced Technology, Discovery Research Laboratories, Nippon Hoechst Marion Roussel, 1-3-2 Minamidai, 350-1165, Kawagoe, Japan
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Fujimura H. Cell-cell recognition and pheromone response of the yeast Saccharomyces globosus. FEMS Microbiol Lett 1999; 173:63-8. [PMID: 10220882 DOI: 10.1111/j.1574-6968.1999.tb13485.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Sexual agglutination and pheromone interaction between cells of two mating types, a and alpha, in the yeast Saccharomyces globosus were studied. S. globosus was shown to produce mating-type-specific factors analogs to a- and alpha-mating pheromones of Saccharomyces cerevisiae and to undergo the sexual agglutination reaction between cells of two mating types. While the sexual agglutination of cells of different species was not observed, mating type a cells of each species were shown to respond to alpha-factors produced by the other species. Thus, the mating response of S. globosus was shown to be identical to what has been observed in two other species of the same genera: S. cerevisiae and Saccharomyces kluyveri.
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6
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Gammie AE, Brizzio V, Rose MD. Distinct morphological phenotypes of cell fusion mutants. Mol Biol Cell 1998; 9:1395-410. [PMID: 9614182 PMCID: PMC25358 DOI: 10.1091/mbc.9.6.1395] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cell fusion in yeast is the process by which two haploid cells fuse to form a diploid zygote. To dissect the pathway of cell fusion, we phenotypically and genetically characterized four cell fusion mutants, fus6/spa2, fus7/rvs161, fus1, and fus2. First, we examined the complete array of single and double mutants. In all cases but one, double mutants exhibited stronger cell fusion defects than single mutants. The exception was rvs161Delta fus2Delta, suggesting that Rvs161p and Fus2p act in concert. Dosage suppression analysis showed that Fus1p and Fus2p act downstream or parallel to Rvs161p and Spa2p. Second, electron microscopic analysis was used to define the mutant defects in cell fusion. In wild-type prezygotes vesicles were aligned and clustered across the cell fusion zone. The vesicles were associated with regions of cell wall thinning. Analysis of Fus- zygotes indicated that Fus1p was required for the normal localization of the vesicles to the zone of cell fusion, and Spa2p facilitated their clustering. In contrast, Fus2p and Rvs161p appeared to act after vesicle positioning. These findings lead us to propose that cell fusion is mediated in part by the localized release of vesicles containing components essential for cell fusion.
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Affiliation(s)
- A E Gammie
- Princeton University, Princeton, New Jersey 08544-1014, USA
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7
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Fujimura HA. Identification of the mgc1 mutation which affects mating-pheromone-induced morphogenesis in the yeast Saccharomyces cerevisiae. FEMS Microbiol Lett 1998; 161:359-64. [PMID: 9570127 DOI: 10.1111/j.1574-6968.1998.tb12969.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Cells of the yeast Saccharomyces cerevisiae undergo morphogenesis in response to the mating pheromones a- and alpha-factors. The 'shmoo' morphology involves localized cell surface projection formation and cytoskeleton protein synthesis. This polarization is presumed to be a prelude to mating between mating partners with opposite mating types, a and alpha. To identify genes involved in pheromone-induced morphogenesis, a system in which a gpa1 fus3 double mutant was used as a parent strain was developed, and mutants which showed altered morphogenesis in response to mating pheromone were identified. The mutation was designated mgc1 for morphogenesis control by mating pheromones. The mgc1 mutant arrested cell division in response to alpha-factor and mated with cells of the opposite mating type, but did not form a typical projection in response to pheromones.
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Affiliation(s)
- H A Fujimura
- Laboratory for Advanced Technology, Nippon Hoechst Marion Roussel, Kawagoe, Japan
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8
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Hung W, Olson KA, Breitkreutz A, Sadowski I. Characterization of the basal and pheromone-stimulated phosphorylation states of Ste12p. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 245:241-51. [PMID: 9151949 DOI: 10.1111/j.1432-1033.1997.00241.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Saccharomyces cerevisiae transcription factor Ste12p is required for basal and activated expression of pheromone-responsive genes, and for invasive growth in haploid cells. In diploid yeast, Ste12p is implicated in pseudohyphal development. The ability of Ste12p to effect these various responses in three different cell types must require stringent regulation of its transcriptional activation function and interaction with additional transcription factors. We have examined the phosphorylation state of Ste12p in untreated and pheromone-treated haploid cells, and found eight constitutively phosphorylated peptides. Phosphorylation at the constitutive sites does not require the protein kinases of the pheromone-response pathway. Treatment of haploid yeast with mating pheromone causes the appearance of novel relatively minor phosphorylations on Ste12p. Brief [35S]methionine labeling reveals novel pheromone-dependent, electrophoretically slower migrating Ste12p species. Similarly, the sole difference we observe in tryptic phosphopeptides generated from Ste12p from pheromone-treated and untreated cells is the transient appearance of two novel minor hydrophobic phosphopeptides. The pheromone-dependent phosphorylation of Ste12p requires an intact pheromone-response pathway and localization of Ste12p to the nucleus, but does not require the Ste12p DNA-binding domain. We conclude from these experiments that the pheromone-response pathway induces the formation of specific hyperphosphorylation on Ste12p, which can only be detected as apparently minor modifications in vivo. We argue that, if Ste12p is regulated by direct pheromone-responsive phosphorylation, then that phosphorylation must be represented by the two novel phosphopeptides. However, we cannot exclude the possibility that pheromone-responsive transcription is controlled by direct phosphorylation of a target other than Ste12p.
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Affiliation(s)
- W Hung
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
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Toda T, Dhut S, Superti-Furga G, Gotoh Y, Nishida E, Sugiura R, Kuno T. The fission yeast pmk1+ gene encodes a novel mitogen-activated protein kinase homolog which regulates cell integrity and functions coordinately with the protein kinase C pathway. Mol Cell Biol 1996; 16:6752-64. [PMID: 8943330 PMCID: PMC231678 DOI: 10.1128/mcb.16.12.6752] [Citation(s) in RCA: 183] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have isolated a gene, pmk1+, a third mitogen-activated protein kinase (MAPK) gene homolog from the fission yeast Schizosaccharomyces pombe. The predicted amino acid sequence shows the most homology (63 to 65% identity) to those of budding yeast Saccharomyces Mpk1 and Candida Mkc1. The Pmk1 protein contains phosphorylated tyrosines, and the level of tyrosine phosphorylation was increased in the dsp1 mutant which lacks an attenuating phosphatase for Pmk1. The level of tyrosine phosphorylation appears constant during hypotonic or heat shock treatment. The cells with pmk1 deleted (delta pmk1) are viable but show various defective phenotypes, including cell wall weakness, abnormal cell shape, a cytokinesis defect, and altered sensitivities to cations, such as hypersensitivity to potassium and resistance to sodium. Consistent with a high degree of conservation of amino acid sequence, multicopy plasmids containing the MPK1 gene rescued the defective phenotypes of the delta pmk1 mutant. The frog MAPK gene also suppressed the pmk1 disruptant. The results of genetic analysis indicated that Pmk1 lies on a novel MAPK pathway which does not overlap functionally with the other two MAPK pathways, the Spk1-dependent mating signal pathway and Sty1/Spc1/Phh1-dependent stress-sensing pathway. In Saccharomyces cerevisiae, Mpk1 is involved in cell wall integrity and functions downstream of the protein kinase C homolog. In contrast, in S. pombe, Pmk1 may not act in a linear manner with respect to fission yeast protein kinase C homologs. Interestingly, however, these two pathways are not independent; instead, they regulate cell integrity in a coordinate manner.
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Affiliation(s)
- T Toda
- Cell Regulation Laboratory, Imperial Cancer Research Fund, London, United Kingdom.
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10
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Fujimura HA. Yeast homolog of mammalian mitogen-activated protein kinase, FUS3/DAC2 kinase, is required both for cell fusion and for G1 arrest of the cell cycle and morphological changes by the cdc37 mutation. J Cell Sci 1994; 107 ( Pt 9):2617-22. [PMID: 7844175 DOI: 10.1242/jcs.107.9.2617] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Saccharomyces cerevisiae FUS3/DAC2 protein kinase, a homolog of mammalian mitogen-activated protein (MAP) kinase, inactivates a G1 cyclin encoded by the CLN3 gene to arrest cell division in the G1 phase and activates a transcriptional factor STE12 in response to mating pheromone during sexual conjugation. To elucidate the role of the FUS3/DAC2 gene product in the mating process, I constructed and characterized dac2 cln3 double mutants. Here, I show that FUS3/DAC2 is required for completion of cell fusion even in the dac2 cln3 double mutants in which the pheromone response is restored, suggesting that FUS3/DAC2 plays a positive role in cell fusion during conjugation. In addition, the cdc dac2 and cdc37 ste double mutants were constructed and investigated for their phenotypes to clarify the relationship between FUS3/DAC2, STE7 or STE11 and CDC gene products (CDC28, 36, 37 and 39). The results indicate that FUS3/DAC2 may act upstream of CDC28 and provide evidence that the G1 arrest and morphological changes conferred by the cdc37 mutation may require FUS3/DAC2 (MAP kinase), STE7(MEK) and STE11 (MEK kinase).
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Affiliation(s)
- H A Fujimura
- Laboratory of Genetics and Microbiology, Developmental and Reproductive Biology Center, Yamagata, Japan
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11
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Yorihuzi T, Ohsumi Y. Saccharomyces cerevisiae MATa mutant cells defective in pointed projection formation in response to alpha-factor at high concentrations. Yeast 1994; 10:579-94. [PMID: 7941743 DOI: 10.1002/yea.320100503] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We have isolated Saccharomyces cerevisiae MATa mutant cells that do not form a pointed projection but elongate in response to alpha-factor at high concentrations. Complementation tests defined three genes, PPF1, PPF2, and PPF3 (for pointed projection formation), necessary for pointed projection formation. Allelism tests with genes known to be needed for projection formation revealed that PPF1 is identical to SPA2, while PPF2 and PPF3 are not allelic to SST2, STE2, SPA2, BEM1 or SLK1/SSP31/BCK1. The morphology of MATa ppf mutants treated with high concentrations of alpha-factor is similar to that of MATa PPF cells treated with alpha-factor at low concentrations. Quantitative mating tests showed that PPF2 and PPF3 are not essential for mating in either MATa or MAT alpha background. Monitoring of division arrest and expression of an alpha-factor-inducible gene revealed that mutations in the PPF genes do not affect the responses of MATa cells to low concentrations of alpha-factor. Unlike wild-type cells, the ppf mutants exhibited early recovery from alpha-factor-induced division arrest. Furthermore, vegetatively growing ppf3-1 cells are slightly defective in cell separation of mother and daughter cells and in selection of the correct bud sites in all cell types. These results indicate that PPF2 and PPF3 are involved in the response to alpha-factor at high concentrations and that PPF3 is also required for proper establishment of polarity in vegetative growth.
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Affiliation(s)
- T Yorihuzi
- Department of Biology, College of Arts and Sciences, University of Tokyo, Japan
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12
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Far1 and Fus3 link the mating pheromone signal transduction pathway to three G1-phase Cdc28 kinase complexes. Mol Cell Biol 1993. [PMID: 8395009 DOI: 10.1128/mcb.13.9.5659] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, the Cdc28 protein kinase controls commitment to cell division at Start, but no biologically relevant G1-phase substrates have been identified. We have studied the kinase complexes formed between Cdc28 and each of the G1 cyclins Cln1, Cln2, and Cln3. Each complex has a specific array of coprecipitated in vitro substrates. We identify one of these as Far1, a protein required for pheromone-induced arrest at Start. Treatment with alpha-factor induces a preferential association and/or phosphorylation of Far1 by the Cln1, Cln2, and Cln3 kinase complexes. This induced interaction depends upon the Fus3 protein kinase, a mitogen-activated protein kinase homolog that functions near the bottom of the alpha-factor signal transduction pathway. Thus, we trace a path through which a mitogen-activated protein kinase regulates a Cdc2 kinase.
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13
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Tyers M, Futcher B. Far1 and Fus3 link the mating pheromone signal transduction pathway to three G1-phase Cdc28 kinase complexes. Mol Cell Biol 1993; 13:5659-69. [PMID: 8395009 PMCID: PMC360296 DOI: 10.1128/mcb.13.9.5659-5669.1993] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In the yeast Saccharomyces cerevisiae, the Cdc28 protein kinase controls commitment to cell division at Start, but no biologically relevant G1-phase substrates have been identified. We have studied the kinase complexes formed between Cdc28 and each of the G1 cyclins Cln1, Cln2, and Cln3. Each complex has a specific array of coprecipitated in vitro substrates. We identify one of these as Far1, a protein required for pheromone-induced arrest at Start. Treatment with alpha-factor induces a preferential association and/or phosphorylation of Far1 by the Cln1, Cln2, and Cln3 kinase complexes. This induced interaction depends upon the Fus3 protein kinase, a mitogen-activated protein kinase homolog that functions near the bottom of the alpha-factor signal transduction pathway. Thus, we trace a path through which a mitogen-activated protein kinase regulates a Cdc2 kinase.
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Affiliation(s)
- M Tyers
- Banting and Best Department of Medical Research, University of Toronto, Ontario, Canada
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14
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Peter M, Gartner A, Horecka J, Ammerer G, Herskowitz I. FAR1 links the signal transduction pathway to the cell cycle machinery in yeast. Cell 1993; 73:747-60. [PMID: 8500168 DOI: 10.1016/0092-8674(93)90254-n] [Citation(s) in RCA: 293] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Alpha factor induces arrest of yeast a cells in G1 and transcription of genes involved in mating. Prior work indicates that FUS3, a member of the MAP kinase family, and FAR1, whose molecular activity is unknown, contribute to cell cycle arrest by inhibiting G1 cyclins. Here we show that FAR1 is a substrate for FUS3 and that this phosphorylation regulates association of FAR1 with CDC28-CLN2 kinase. We show also that FAR1 is phosphorylated in vitro by the CDC28-CLN2 complex and in vivo in a CDC28-dependent manner. Mutational analysis of FAR1 reveals a correlation between its ability to associate with CDC28-CLN2 and to arrest the cell cycle. These results suggest that FAR1 protein is the link between the signaling pathway and the cell cycle machinery.
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Affiliation(s)
- M Peter
- Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448
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15
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Fujimura HA. The DAC2/FUS3 protein kinase is not essential for transcriptional activation of the mating pheromone response pathway in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1992; 235:450-2. [PMID: 1465115 DOI: 10.1007/bf00279392] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The DAC2/FUS3 gene of Saccharomyces cerevisiae, which encodes a CDC28/cdc2-related protein kinase, is essential both for the arrest of cell division induced by mating pheromones and for cell fusion during conjugation. To elucidate the role of the DAC2 gene product in the pheromone response pathway, I determined the nucleotide sequence of the DAC2 gene and characterized two types of deletion mutants of the DAC2 gene. Here, I show that the DAC2 gene is identical to the FUS3 gene and that dac2/fus3 deletion mutants respond to mating pheromones by activating transcription. Therefore, the DAC2/FUS3 gene is not essential for transcriptional activation in the pheromone response pathway. The DAC2/FUS3 protein kinase has a positive role in cell fusion during sexual conjugation.
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Affiliation(s)
- H A Fujimura
- Laboratory for Molecular Biology, Hoechst Japan Limited, Kawagoe
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16
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Gartner A, Nasmyth K, Ammerer G. Signal transduction in Saccharomyces cerevisiae requires tyrosine and threonine phosphorylation of FUS3 and KSS1. Genes Dev 1992; 6:1280-92. [PMID: 1628831 DOI: 10.1101/gad.6.7.1280] [Citation(s) in RCA: 244] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The FUS3 and KSS1 kinases are components of the pheromone-dependent signal transduction pathway in yeast. We show that FUS3 and KSS1 become rapidly phosphorylated after pheromone treatment. Similar to mammalian MAP kinases, this modification occurs at two amino acids of FUS3, threonine-180 and tyrosine-182. A mutation introduced at either position results in complete loss of function in vivo. Amino acid substitutions that destroy catalytic activity of the kinase do not prevent phosphorylation of the mutant products, a result that excludes an autocatalytic activation pathway. The modification of FUS3 is dependent on kinases encoded by the STE11 and STE7 genes. Furthermore, a hyperactive allele of STE11 causes increased phosphorylation of FUS3 in the absence of pheromone stimulation. Thus, either STE7 or STE11 could be the kinase responsible for the phosphorylation of FUS3.
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Affiliation(s)
- A Gartner
- Institute of Molecular Pathology, Vienna, Austria
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