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Shimizu M, Li W, Covitz PA, Hara M, Shindo H, Mitchell AP. Genomic footprinting of the yeast zinc finger protein Rme1p and its roles in repression of the meiotic activator IME1. Nucleic Acids Res 1998; 26:2329-36. [PMID: 9580682 PMCID: PMC147578 DOI: 10.1093/nar/26.10.2329] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The zinc finger protein Rme1p is a negative regulator of the meiotic activator IME1 in Saccharomyces cerevisiae . Prior studies have shown that Rme1p binds in vitro to a site near nt -2030 in the IME1 upstream region, but a genomic mutation in that site has little effect on repression of IME1 . To identify Rme1p binding sites in vivo , we have examined the binding of Rme1p to genomic sites through in vivo footprinting. We show that Rme1p binds to two sites in the IME1 upstream region, near nt -1950 and -2030. Mutations in both binding sites abolish repression of chromosomal IME1 by Rme1p, whereas a mutation in either single site causes partial derepression. Therefore, both Rme1p binding sites are essential for repression of IME1 . Prior studies have shown that repression by Rme1p depends upon RGR1 and SIN4 , which specify RNA polymerase II mediator subunits that are required for normal nucleosome density. We find that RGR1 and SIN4 are not simply required for Rme1p to bind to DNA in vivo . These results suggest that Rme1p functions directly as a repressor of IME1 and that Rgr1p and Sin4p are required for DNA-bound Rme1p to exert repression.
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Affiliation(s)
- M Shimizu
- School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
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52
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Abstract
Meiosis and sporulation in the yeast Saccharomyces cerevisiae has been classically viewed as an example of unicellular, eukaryotic differentiation that occurs in response to nutritional starvation. We present evidence that S. cerevisiae produces an extracellular factor(s), called meiosis-promoting factor (MEP), that is required, in addition to starvation conditions, for efficient meiosis and sporulation. This factor is secreted and accumulates in a cell density-dependent fashion such that cells at a low density sporulate poorly under conditions in which cells at a high density sporulate efficiently. Conditioned medium from sporulating cells at a high density contains a small anionic molecule that has cytostatic activity and stimulates sporulation of cells at low density under a normal starvation condition. These results indicate that MEP-mediated social communication between cells is required for meiosis and sporulation.
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Affiliation(s)
- M Hayashi
- Center for Gene Science, Hiroshima University, Higashi-Hiroshima, Japan
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53
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Ohkuni K, Hayashi M, Yamashita I. Bicarbonate-mediated social communication stimulates meiosis and sporulation of Saccharomyces cerevisiae. Yeast 1998; 14:623-31. [PMID: 9639309 DOI: 10.1002/(sici)1097-0061(199805)14:7<623::aid-yea264>3.0.co;2-d] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Meiosis and sporulation in the yeast Saccharomyces cerevisiae requires social communication, mediated by an extracellular factor which is secreted from cells during sporulation and accumulates in a cell density-dependent manner. We show here genetic and biochemical analyses supporting our conclusion that the extracellular factor is bicarbonate acting as an alkali to elevate extracellular pH. Sporulation defects of mdh1 (mitochondrial malate dehydrogenase) mutants and of wild-type cells at low density were rescued extracellularly by addition of bicarbonate or other alkaline solutions to raise medium pH. Addition of bicarbonate (or alkalization of medium) raised steady-state levels of mRNA in respiration-deficient mdh1 mutants and inhibited proliferation of wild-type cells at low density. These results indicate that the two conditions (respiration competency and high cell density), required for meiosis and sporulation, are essential for extracellular accumulation of bicarbonate and resulting alkalization of medium.
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Affiliation(s)
- K Ohkuni
- Center for Gene Science, Hiroshima University, Higashi-Hiroshima, Japan
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54
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Ramaswamy NT, Li L, Khalil M, Cannon JF. Regulation of yeast glycogen metabolism and sporulation by Glc7p protein phosphatase. Genetics 1998; 149:57-72. [PMID: 9584086 PMCID: PMC1460142 DOI: 10.1093/genetics/149.1.57] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Glc7p is an essential serine/threonine type 1 protein phosphatase (PP1) from the yeast Saccharomyces cerevisiae, which has a role in many processes including cell cycle progression, sporulation, glycogen accumulation, translation initiation, and glucose repression. Two hallmarks of PP1 enzymes are very high amino acid sequence conservation and association of the catalytic subunit with a variety of noncatalytic, regulatory subunits. We tested the hypothesis that PP1 sequence conservation was the result of each PP1 residue playing a role in multiple intermolecular interactions. Analysis of 24 glc7 mutants, isolated primarily by their glycogen accumulation traits, revealed that every mutated Glc7p residue altered many noncatalytic subunit affinities and conferred unselected sporulation traits to various degrees. Furthermore, quantitative analysis showed that Glc7p affinity for the glycogen-binding noncatalytic subunit Gac1p was not the only parameter that determines the glycogen accumulation by a glc7 mutant. Sds22p is one Glc7p noncatalytic subunit that is essential for mitotic growth. Surprisingly, several mutant Glc7p proteins had undetectable affinity for Sds22p, yet grew apparently normally. The characterization of glc7 diploid sporulation revealed that Glc7p has at least two meiotic roles. Premeiotic DNA synthesis was undetectable in glc7 mutants with the poorest sporulation. In the glc7 diploids examined, expression of the meiotic inducer IME1 was proportional to the glc7 diploid sporulation frequency. Moreover, IME1 hyperexpression could not suppress glc7 sporulation traits. The Glc7p/Gip1p holoenzyme may participate in completion of meiotic divisions or spore packaging because meiotic dyads predominate when some glc7 diploids sporulate.
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Affiliation(s)
- N T Ramaswamy
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri 65212, USA
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55
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Benni ML, Neigeborn L. Identification of a new class of negative regulators affecting sporulation-specific gene expression in yeast. Genetics 1997; 147:1351-66. [PMID: 9383076 PMCID: PMC1208257 DOI: 10.1093/genetics/147.3.1351] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We characterized two yeast loci, MDS3 and PMD1, that negatively regulate sporulation. Initiation of sporulation is mediated by the meiotic activator IME1, which relies on MCK1 for maximal expression. We isolated the MDS3-1 allele (encoding a truncated form of Mds3p) as a suppressor that restores IME1 expression in mck1 mutants. mds3 null mutations confer similar suppression phenotypes as MDS3-1, indicating that Mds3p is a negative regulator of sporulation and the MDS3-1 allele confers a dominant-negative phenotype. PMD1 is predicted to encode a protein sharing significant similarity with Mds3p. mds3 pmd1 double mutants are better suppressors of mck1 than is either single mutant, indicating that Mds3p and Pmd1p function synergistically. Northern blot analysis revealed that suppression is due to increased IME1 transcript accumulation. The roles of Mds3p and Pmd1p are not restricted to the MCK1 pathway because mds3 pmd1 mutations also suppress IME1 expression defects associated with MCK1-independent sporulation mutants. Furthermore, mds3 pmd1 mutants express significant levels of IME1 even in vegetative cells and this unscheduled expression results in premature sporulation. These phenotypes and interactions with RAS2-Val19 suggest that unscheduled derepression of IME1 is probably due to a defect in recognition of nutritional status.
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Affiliation(s)
- M L Benni
- Waksman Institute of Microbiology, Rutgers, the State University of New Jersey, Piscataway 08854-8020, USA
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56
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Tsui K, Simon L, Norris D. Progression into the first meiotic division is sensitive to histone H2A-H2B dimer concentration in Saccharomyces cerevisiae. Genetics 1997; 145:647-59. [PMID: 9055075 PMCID: PMC1207850 DOI: 10.1093/genetics/145.3.647] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The yeast Saccharomyces cerevisiae contains two genes for histone H2A and two for histone H2B located in two divergently transcribed gene pairs: HTA1-HTB1 and HTA2-HTB2. Diploid strains lacking HTA1-HTB1 (hta1-htb1 delta/hta1-htb1 delta, HTA2-HTB2/HTA2-HTB2) grow vegetatively, but will not sporulate. This sporulation phenotype results from a partial depletion of H2A-H2B dimers. Since the expression patterns of HTA1-HTB1 and HTA2-HTB2 are similar in mitosis and meiosis, the sporulation pathway is therefore more sensitive than the mitotic cycle to depletion of H2A-H2B dimers. After completing premeiotic DNA replication, commitment to meiotic recombination, and chiasma resolution, the hta1-htb1 delta/hta1-htb1 delta, HTA2-HTB2/HTA2-HTB2 mutant arrests before the first meiotic division. The arrest is not due to any obvious disruptions in spindle pole bodies or microtubules. The meiotic block is not bypassed in backgrounds homozygous for spo13, rad50 delta, or rad9 delta mutations, but is bypassed in the presence of hydroxyurea, a drug known to inhibit DNA chain elongation. We hypothesize that the deposition of H2A-H2B dimers in the mutant is unable to keep pace with the replication fork, thereby leading to a disruption in chromosome structure that interferes with the meiotic divisions.
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Affiliation(s)
- K Tsui
- The Waksman Institute, Rutgers, The State University of New Jersey, Piscataway 08855-0759, USA
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57
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Li W, Mitchell AP. Proteolytic activation of Rim1p, a positive regulator of yeast sporulation and invasive growth. Genetics 1997; 145:63-73. [PMID: 9017390 PMCID: PMC1207785 DOI: 10.1093/genetics/145.1.63] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In the yeast Saccharomyces cerevisiae, rim1, 8, 9, or 13 mutations cause four phenotypes: poor growth at low temperature, altered colony morphology, inefficient sporulation due to reduced expression of the meiotic activator IME1, and, as shown here, defective invasive growth. In this report, we have determined the relationship between RIM1 and the other genes, RIM8, 9, and 13, in this group. We have analyzed production of epitope-tagged Rim1p derivatives with HA epitopes at the N-terminus or in the middle of the protein. These Rim1p derivatives exist primarily as a small form (90 kD for Rim1-HA2p) in wild-type cells and as a large form (98 kD for Rim1-HA2p) in rim8, 9, and 13 mutants. We have also analyzed production of beta-galactosidase in strains that express a RIM1-lacZ fusion gene. beta-galactosidase exists primarily as a approximately 130 kD form in wild-type cells and as a approximately 190 kD form in rim9 mutants. These results indicate that Rim1p undergoes C-terminal proteolytic cleavage, and that rim8, 9, and 13 mutations block cleavage. Expression of a Rim1p C-terminal deletion derivative suppresses rim8, 9, and 13 mutations. Thus the phenotypes of rim8, 9, and 13 mutants arise from the defect in Rim1p C-terminal cleavage. Cleavage of Rim1p, like that of its Aspergillus nidulans homologue PacC, is stimulated under alkaline growth conditions. Therefore, Rim1p, PacC and their respective processing pathways may represent a conserved signal transduction pathway.
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Affiliation(s)
- W Li
- Department of Microbiology and Institute of Cancer Research, Columbia University, New York, New York 10032, USA
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58
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Park HD, Beeser AE, Clancy MJ, Cooper TG. The S. cerevisiae nitrogen starvation-induced Yvh1p and Ptp2p phosphatases play a role in control of sporulation. Yeast 1996; 12:1135-51. [PMID: 8896280 DOI: 10.1002/(sici)1097-0061(19960915)12:11<1135::aid-yea11>3.0.co;2-l] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Starvation for nitrogen in the absence of a fermentable carbon source causes diploid Saccharomyces cerevisiae cells to leave vegetative growth, enter meiosis, and sporulare; the former nutritional condition also induces expression of the YVH1 gene that encodes a protein phosphatase. This correlation prompted us to determine whether the Yvh1p phosphatase was a participant in the network that controls the onset of meiosis and sporulation. We found that expression of the IME2 gene, encoding a protein kinase homologue required for meiosis- and sporulation-specific gene expression, is decreased in a yvh1 disrupted strain. We also observed a decrease, albeit a smaller one, in the expression of IME1 which encodes an activator protein required for IME2 expression. Under identical experimental conditions, expression of the MCKI and IME4 genes (which promote sporulation but do not require Ime1p for expression) was not affected. These results demonstrate the specificity of the yvh1 disruption phenotype. They suggest that decreased steady-state levels of IME1 and IME2 mRNA were not merely the result of non-specific adverse affects on nucleic acid metabolism caused by the yvh1 disruption. Sporulation of a homozygous yvh1 disruption mutant was delayed and less efficient overall compared to an isogenic wild-type strain, a result which correlates with decreased IME1 and IME2 gene expression. We also observed that expression of the PTP2 tyrosine phosphatase gene (a negative regulator of the osmosensing MAP kinase cascade), but not the PTP1 gene (also encoding a tyrosine phosphatase) was induced by nitrogen-starvation. Although disruption of PTP2 alone did not demonstrably affect sporulation or IME2 gene expression, sporulation was decreased more in a yvh1, ptp2 double mutant than in a yvh1 single mutant; it was nearly abolished in the double mutant. These data suggest that the YVH1 and PTP2 encoded phosphatases likely participate in the control network regulating meiosis and sporulation. Expression of YVH1 and PTP2 was not affected by nitrogen source quality (asparagine compared to proline) suggesting that nitrogen starvation-induced YVH1 and PTP2 expression and sensitivity to nitrogen catabolite repression are on two different branches of the nitrogen regulatory network.
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Affiliation(s)
- H D Park
- Department of Microbiology and Immunology, University of Tennessee, Memphis 38163, USA
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59
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Svetlov VV, Cooper TG. Review: compilation and characteristics of dedicated transcription factors in Saccharomyces cerevisiae. Yeast 1995; 11:1439-84. [PMID: 8750235 DOI: 10.1002/yea.320111502] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- V V Svetlov
- Department of Microbiology and Immunology, University of Tennessee, Memphis 36163, USA
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60
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Abstract
We have identified a gene, GSG1 (general sporulation gene 1), required for sporulation in Saccharomyces cerevisiae. Diploids homozygous for a disruption of GSG1 fail to sporulate. The gene has an open reading frame of 2094 bp, encoding a polypeptide with an expected size of 77 kDa. GSG1 is expressed mitotically in both a and alpha haploids, and both mitotically and meiotically in diploids. The message level of GSG1 increases approximately two-fold after 4-6 h of sporulation. gsg1 mutants enter pre-meiotic DNA synthesis later than wild-type diploids. Mutant diploids are not rescued by spo13. These results suggest that GSG1 has a role late in meiosis following DNA replication.
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Affiliation(s)
- M D Kaytor
- Department of Biochemistry, University of Minnesota, Minneapolis 55455, USA
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61
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Anderson SF, Steber CM, Esposito RE, Coleman JE. UME6, a negative regulator of meiosis in Saccharomyces cerevisiae, contains a C-terminal Zn2Cys6 binuclear cluster that binds the URS1 DNA sequence in a zinc-dependent manner. Protein Sci 1995; 4:1832-43. [PMID: 8528081 PMCID: PMC2143208 DOI: 10.1002/pro.5560040918] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
UME6 is a protein of 836 amino acids from Saccharomyces cerevisiae that acts as a repressor and activator of several early meiotic genes. UME6 contains, near the C-terminus, the amino acid sequence-771C-X2-C-X6-C-X6-C-X2-C-X6-C-, in which the spacings of the six Cys residues are identical to those found in 39 N-terminal Cys-rich DNA binding subdomains of fungal transcription factors. This sequence has been shown in GAL4 and other proteins to form a zinc binuclear cluster. In spite of the different location, the C-rich sequence, cloned and over-produced within the last 111 amino acid residues of UME6, UME6(111), forms a binuclear cluster and exhibits a Zn-dependent binding to the URS1 DNA sequence. The latter, TAGCCGCCGA, is required for the repression or activation of meiosis-specific genes by UME6. UME6(111) contains 1.8 +/- 0.4 mol Zn/mol protein and the Zn can be exchanged for Cd to yield a protein containing 1.9 +/- 0.1 mol Cd/mol protein. At 5 degrees C, 113Cd2UME6(111) shows two 113Cd NMR signals, with chemical shifts of 699 and 689 ppm, similar to those observed for 113Cd2GAL4(149). The magnitude of these chemical shifts suggests that each 113Cd nucleus is coordinated to four -S- ligands, compatible with a 113Cd2 cluster structure in which two thiolates from bridging ligands. The entire UME6 gene has been cloned and overexpressed and binds more tightly to the URS1 sequence than the zinc binuclear cluster domain alone. DNase I footprints of UME6 on URS1-containing DNA show that the protein protects the phosphodiesters of the 5'-CCGCCG-3' region within the URS1 sequence.
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Affiliation(s)
- S F Anderson
- Department of Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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62
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Rockmill B, Engebrecht JA, Scherthan H, Loidl J, Roeder GS. The yeast MER2 gene is required for chromosome synapsis and the initiation of meiotic recombination. Genetics 1995; 141:49-59. [PMID: 8536989 PMCID: PMC1206739 DOI: 10.1093/genetics/141.1.49] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Mutation of the MER2 gene of Saccharomyces cerevisiae confers meiotic lethality. To gain insight into the function of the Mer2 protein, we have carried out a detailed characterization of the mer2 null mutant. Genetic analysis indicates that mer2 completely eliminates meiotic interchromosomal gene conversion and crossing over. In addition, mer2 abolishes intrachromosomal meiotic recombination, both in the ribosomal DNA array and in an artificial duplication. The results of a physical assay demonstrate that the mer2 mutation prevents the formation of meiosis-specific, double-strand breaks, indicating that the Mer2 protein acts at or before the initiation of meiotic recombination. Electron microscopic analysis reveals that the mer2 mutant makes axial elements, which are precursors to the synaptonemal complex, but homologous chromosomes fail to synapse. Fluorescence in situ hybridization of chromosome-specific DNA probes to spread meiotic chromosomes demonstrates that homolog alignment is also significantly reduced in the mer2 mutant. Although the MER2 gene is transcribed during vegetative growth, deletion or overexpression of the MER2 gene has no apparent effect on mitotic recombination or DNA damage repair. We suggest that the primary defect in the mer2 mutant is in the initiation of meiotic genetic exchange.
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Affiliation(s)
- B Rockmill
- Department of Biology, Yale University, New Haven, Connecticut 06520-8103, USA
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63
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Rasmussen SW. A 37.5 kb region of yeast chromosome X includes the SME1, MEF2, GSH1 and CSD3 genes, a TCP-1-related gene, an open reading frame similar to the DAL80 gene, and a tRNA(Arg). Yeast 1995; 11:873-83. [PMID: 7483851 DOI: 10.1002/yea.320110909] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The complete DNA sequence of cosmid clone p59 comprising 37,549 bp derived from chromosome X was determined from an ordered set of subclones. The sequence contains 14 open reading frames (ORFs) containing at least 100 consecutive sense codons. Four of the ORFs represent already known and sequenced yeast genes: B645 is identical to the SME1 gene encoding a protein kinase, required for induction of meiosis in yeast, D819 represents the MEF2 gene probably encoding a second mitochondrial elongation factor-like protein, D678 is identical to the yeast GSH1 gene encoding gamma-glutamylcysteine synthetase and B746 is identical to the CSD3 gene, which plays an as yet unidentified role in chitin biosynthesis and/or its regulation. The deduced amino acid sequence of A550 is 63% identical to the Cc eta subunit of a murine TCP-1-containing chaperonin and more than 35% identical to thermophilic factor 55 from Sulfolobus shibatae, as well as to a number of proteins belonging to the chaperonin TCP-1 family. Open reading frame F551 exhibits homology to two regions of the DAL80 gene located on yeast chromosome XI encoding a pleiotropic negative regulatory protein. In addition, extensive homology was detected in three regions including parts of ORFs A560, B746/CSD3 and the incomplete ORF C852 to three consecutive ORFs of unknown function in the middle of the right arm of chromosome XI. Finally, the sequence contained a tRNA(Arg3) (AGC) gene.
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Affiliation(s)
- S W Rasmussen
- Department of Physiology, Carlsberg Laboratory, Copenhagen, Denmark
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64
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Shefer-Vaida M, Sherman A, Ashkenazi T, Robzyk K, Kassir Y. Positive and negative feedback loops affect the transcription of IME1, a positive regulator of meiosis in Saccharomyces cerevisiae. DEVELOPMENTAL GENETICS 1995; 16:219-28. [PMID: 7796531 DOI: 10.1002/dvg.1020160302] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The IME1 gene of Saccharomyces cerevisiae encodes a transcription factor that is required for the expression of meiosis-specific genes. Like many of the genes it regulates, IME1 itself is expressed according to the following complex pattern: barely detectable levels during vegetative growth, and high induced levels under starvation conditions, followed by a subsequent decline in the course of meiosis. This report examines the influence of Ime1 protein on its own expression, demonstrating feedback regulation. Disruption of either IME1 or IME2 leads to constantly increasing levels of Ime1-lacZ expression, under meiotic conditions. This apparent negative regulation is due to cis elements in the IME1 upstream region, which confer transient meiotic expression to heterologous promoter-less genes. A specific DNA/protein complex, whose level is transiently increased under meiotic conditions, is detected on this element. In ime1- diploids, the level of this DNA/protein complex increases, without any decline. These results indicate that the transient expression of IME1 is apparently due to transcriptional regulation. This report also presents evidence suggesting that Ime1p is directly responsible for regulating its own transcription. Positive feedback regulation in mitotic conditions is suggested by the observation that overexpression of Ime1p leads to increased levels of IME1-lacZ. Negative autoregulation in meiotic cultures is demonstrated by the observation that a specific point mutation in IME1, ime1-3, permits expression of meiosis-specific genes, as well as induction of meiosis, but is defective in negative-feedback regulation of IME1.
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Affiliation(s)
- M Shefer-Vaida
- Department of Biology, Technion-Israel Institute of Technology, Haifa
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65
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Yu G, Li J, Young D. The Schizosaccharomyces pombe pka1 gene, encoding a homolog of cAMP-dependent protein kinase. Gene 1994; 151:215-20. [PMID: 7828877 DOI: 10.1016/0378-1119(94)90659-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have isolated 16 independent Schizosaccharomyces pombe cDNA clones that suppress the temperature-sensitive (ts) phenotype of a Saccharomyces cerevisiae strain containing the dominant-negative RAS2val19ala22 allele. Fourteen of these cDNAs encode Sz. pombe Ras1. The other two clones encode the C-terminal region of a protein we have named Pka1. We have cloned the pka1 gene from a Sz. pombe genomic library. It contains an uninterrupted open reading frame encoding a 512-amino-acid (aa) protein. The C-terminal region (aa 200-512) of Pka1 is 51-63% identical to cAMP-dependent protein kinase (Pka) catalytic subunits from other eukaryotes. Production of Pka1 suppresses the ts phenotypes exhibited by Sa. cerevisiae ras1-ras2ts or cyr1ts strains. Furthermore, overproduction of Pka1 in Sz. pombe results in a sterile phenotype and an abnormal morphology similar to that exhibited by cells in which the cAMP pathway is constitutively activated. These observations suggest that pka1 encodes the Sz. pombe Pka catalytic subunit.
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Affiliation(s)
- G Yu
- Department of Medical Biochemistry, University of Calgary Health Sciences Centre, Alberta, Canada
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66
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Covitz PA, Song W, Mitchell AP. Requirement for RGR1 and SIN4 in RME1-dependent repression in Saccharomyces cerevisiae. Genetics 1994; 138:577-86. [PMID: 7851756 PMCID: PMC1206209 DOI: 10.1093/genetics/138.3.577] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
RME1 is a zinc-finger protein homolog that functions as a repressor of the meiotic activator IME1. RME1 is unusual among yeast repressors in two respects: it acts over a considerable distance (2 kbp) and it can activate transcription from a binding site separated from its natural flanking region. To identify genes required for RME1 to exert repression, we have selected mutants with improved RME1-dependent activation. One rare mutant was defective in RME1-dependent repression of an artificial reporter gene as well as the native IME1 gene. The mutation permits sporulation of a/a diploids, which express RME1 from its natural promoter, and of a/alpha diploids constructed to express RME1 from the GAL1 promoter. The mutation also causes temperature-sensitive growth and a methionine or cysteine requirement. Analysis of a complementing genomic clone indicates that the mutation lies in a known essential gene, RGR1. Prior studies have indicated a functional relationship between RGR1 and SIN4 (also called TSF3); we have found that a sin4 null mutation also causes a defect in RME1-dependent repression and a methionine or cysteine requirement. The rgr1 and sin4 mutations do not cause a reduction of RME1 polypeptide levels. The defect in RME1-dependent repression may result from effects of sin4 and, presumably, rgr1 on chromatin structure.
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Affiliation(s)
- P A Covitz
- Department of Microbiology, Columbia University, New York, New York 10032
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67
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Navon A, Schwarz Y, Hazan B, Kassir Y, Nir U. Meiosis-dependent tyrosine phosphorylation of a yeast protein related to the mouse p51ferT. MOLECULAR & GENERAL GENETICS : MGG 1994; 244:160-7. [PMID: 8052235 DOI: 10.1007/bf00283517] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The FER locus of the mouse encodes two mRNA species: one is constitutively transcribed, giving rise to a 94 kDa tyrosine kinase (p94ferT); the second is a meiosis-specific RNA that gives rise to a 51 kDa tyrosine kinase (p51ferT). The p51ferT RNA and protein accumulate in primary spermatocytes that are in prophase of the first meiotic division. By using polyclonal antibodies directed against synthetic peptides derived from the unique amino-terminus of the mouse p51ferT, a 51 kDa phosphotyrosyl protein --p51y-- was identified in Saccharomyces cerevisiae. The p51y protein is constitutively expressed in yeast, but in meiotic cells, concomitantly with commitment to meiotic recombination, its level of phosphorylation on tyrosine residues is increased. A different pattern of phosphorylation is observed on serine residues: at early meiotic times the level is decreased, while in later meiotic time the level increases, reaching the vegetative level. When p51ferT is ectopically expressed in yeast, it is active, leading to preferential phosphorylation of an approx. 65 kDa protein. A similar pattern of phosphorylation by p51ferT is seen in mammalian cells.
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Affiliation(s)
- A Navon
- Department of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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68
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Suizu T, Tsutsumi H, Kawado A, Murata K, Imayasu S. On the importance of calcium and magnesium ions in yeast sporulation. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0922-338x(94)90233-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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69
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Mandel S, Robzyk K, Kassir Y. IME1 gene encodes a transcription factor which is required to induce meiosis in Saccharomyces cerevisiae. DEVELOPMENTAL GENETICS 1994; 15:139-47. [PMID: 8205723 DOI: 10.1002/dvg.1020150204] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previous studies have shown that the IME1 gene is required for sporulation and the expression of meiosis specific genes in Saccharomyces cerevisiae. However, sequence analysis has not revealed the precise functional role of the Ime1 protein. By engineering constructs which express various portions of the Ime1p fused to either the DNA binding or transcriptional activation domains of GAL4, we have conclusively demonstrated that IME1 is a transcription factor, apparently required for sporulation to activate the transcription of meiosis specific genes. The full Ime1p, when fused to the GAL4 DNA binding domain, can both activate GAL1-lacZ expression, and complement ime1-0 (a null allele) for the ability to sporulate, and transcriptionally activate IME2, a meiosis specific gene. As successively larger portions of the encoded Ime1p N-terminus are deleted from the GAL4(bd)-IME1 construct, the encoded fusion proteins retain the ability to complement an ime1 null allele, despite a decreasing ability to activate GAL1-lacZ transcription. However, a fusion construct which retains only the last 45 C-terminal amino acids of IME1 provides neither transcriptional activation of GAL1-lacZ nor complementation of ime1-0. Fusion of a GAL4 activation domain to this portion of IME1, results in a construct with a restored ability to complement an ime1-0 allele. This restored ability is dependent upon galactose induction. We conclude, therefore, that IME1 functions in meiosis as a transcriptional activator.
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Affiliation(s)
- S Mandel
- Department of Biology, Technion-Israel Institute of Technology, Haifa
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70
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Yamashita I. Isolation and characterization of the SUD1 gene, which encodes a global repressor of core promoter activity in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1993; 241:616-26. [PMID: 8264536 DOI: 10.1007/bf00279904] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The SUD1 gene was identified during a hunt for mutants that are able to express an sta1 gene (encoding an extracellular glucoamylase) lacking an upstream activation sequence (UAS) for transcription. A null allele of sud1 alleviated the transcriptional defect of the UAS-less sta1 and also suppressed mutations in trans-acting genes (GAM1/SNF2 and GAM3/ADR6) required for transcription of STA1. The mutation also increased expression from various core promoters (CYC1, CUP1, HIS3, PUT1, and PUT2), suggesting that the SUD1 protein is a global transcriptional regulator that plays a negative role at or near the TATA element. However, the SUD1 function was ineffective on promoters containing a UAS from either STA1 or GAL10 under derepressed conditions. The sud1 mutation suppressed the salt-sensitive cell growth phenotype caused by elevated levels of the TATA-binding protein (SPT15), further suggesting a transcriptional role for SUD1. sud1 cells showed additional pleiotropic phenotypes: temperature-sensitive (ts) growth, reduced efficiencies of sporulation, and sensitivity to heat shock and nitrogen starvation. The SUD1 gene is predicted to encode a 64 kDa, hydrophilic protein.
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Affiliation(s)
- I Yamashita
- Center for Gene Science, Hiroshima University, Japan
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71
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Weisbrot DR, Khorkova O, Lin H, Henderson AS, Goodman R. The effect of low frequency electric and magnetic fields on gene expression in Saccharomyces cerevisiae. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/0302-4598(93)80005-f] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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72
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Smith HE, Driscoll SE, Sia RA, Yuan HE, Mitchell AP. Genetic evidence for transcriptional activation by the yeast IME1 gene product. Genetics 1993; 133:775-84. [PMID: 8462841 PMCID: PMC1205399 DOI: 10.1093/genetics/133.4.775] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
IME1 is required in yeast for meiosis and for expression of IME2 and other early meiotic genes. IME1 is a 360-amino acid polypeptide with central and C-terminal tyrosine-rich regions. We report here that a fusion protein composed of the lexA DNA-binding domain and IME1 activates transcription in vivo of a reporter gene containing upstream lexA binding sites. Activation by the fusion protein shares several features with natural IME1 activity: both are dependent on the RIM11 gene product; both are impaired by the same ime1 missense mutations; both are restored by intragenic suppressors. The central tyrosine-rich region is sufficient to activate transcription when fused to lexA. Deletion of this putative activation domain results in a defective IME1 derivative. Function of the deletion derivative is restored by fusion to the acidic Herpesvirus VP16 activation domain. The C-terminal tyrosine-rich region is dispensable for transcriptional activation; rather it renders activation dependent upon starvation and RIM11. Immunofluorescence studies indicate that an IME1-lacZ fusion protein is concentrated in the nucleus. These observations are consistent with a model in which IME1 normally stimulates IME2 expression by providing a transcriptional activation domain at the IME2 5' regulatory region.
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Affiliation(s)
- H E Smith
- Institute of Cancer Research, Columbia University, New York, New York 10032
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73
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Matsuura A, Anraku Y. Characterization of the MKS1 gene, a new negative regulator of the Ras-cyclic AMP pathway in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1993; 238:6-16. [PMID: 8386801 DOI: 10.1007/bf00279524] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In order to isolate genes that function downstream of the Ras-cAMP pathway in Saccharomyces cerevisiae, a YEp13-based genomic library was screened for clones that inhibit growth of cells with diminished A-kinase activity. One such gene, MKS1, was found to encode a hydrophilic 52 kDa protein that shares weak homology with the yeast SPT2/SIN1 gene product. Three lines of evidence suggest that the MKS1 gene product is a negative regulator downstream of the Ras-cAMP pathway: (i) overexpression of MKS1 inhibits growth of cyr1 disruptant cells on YPD medium containing a low concentration of cAMP; (ii) overexpression of MKS1 does not affect TPK1 expression; and (iii) the temperature-sensitive cyr1-230 mutation is partially suppressed by mks1 disruption. The mks1 mutant shows similar phenotypes to gal11/spt13, i.e., it cannot grow on YPGal containing ethidium bromide at 25 degrees C, or on YPGly or SGal at 37 degrees C. The mks1 gal11 double mutant shows more marked phenotypic changes than the single mutants. These results suggest that MKS1 is involved in transcriptional regulation of several genes by cAMP.
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Affiliation(s)
- A Matsuura
- Department of Biology, Faculty of Science, University of Tokyo, Japan
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74
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Transcriptional repression in Saccharomyces cerevisiae by a SIN3-LexA fusion protein. Mol Cell Biol 1993. [PMID: 8441414 DOI: 10.1128/mcb.13.3.1805-1814,1993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
The yeast SIN3 gene (also known as SDI1, UME4, RPD1, and GAM2) has been identified as a transcriptional regulator. Previous work has led to the suggestion that SIN3 regulates transcription via interactions with DNA-binding proteins. Although the SIN3 protein is located in the nucleus, it does not bind directly to DNA in vitro. We have expressed a LexA-SIN3 fusion protein in Saccharomyces cerevisiae and show that this fusion protein represses transcription from heterologous promoters that contain lexA operators. The predicted amino acid sequence of the SIN3 protein contains four copies of a paired amphipathic helix (PAH) motif, similar to motifs found in HLH (helix-loop-helix) and TPR (tetratricopeptide repeat) proteins, and these motifs are proposed to be involved in protein-protein interactions. We have conducted a deletion analysis of the SIN3 gene and show that the PAH motifs are required for SIN3 activity. Additionally, the C-terminal region of the SIN3 protein is sufficient for repression activity in a LexA-SIN3 fusion, and deletion of a PAH motif in this region inactivates this repression activity. A model is presented in which SIN3 recognizes specific DNA-binding proteins in vivo in order to repress transcription.
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75
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Sherman A, Shefer M, Sagee S, Kassir Y. Post-transcriptional regulation of IME1 determines initiation of meiosis in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1993; 237:375-84. [PMID: 8483452 DOI: 10.1007/bf00279441] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The IME1 gene of Saccharomyces cerevisiae is required for initiation of meiosis. Transcription of IME1 is detected under conditions which are known to induce initiation of meiosis, namely starvation for nitrogen and glucose, and the presence of MATa1 and MAT alpha 2 gene products. In this paper we show that IME1 is also subject to translational regulation. Translation of IME1 mRNA is achieved either upon nitrogen starvation, or upon G1 arrest. In the presence of nutrients, constitutively elevated transcription of IME1 is also sufficient for the translation of IME1 RNA. Four different conditions were found to cause expression of Ime1 protein in vegetative cultures: elevated transcription levels due to the presence of IME1 on a multicopy plasmid; elevated transcription provided by a Gal-IME1 construct; G1 arrest due to alpha-factor treatment; G1 arrest following mild heat-shock treatment of cdc28 diploids. Using these conditions, we obtained evidence that starvation is required not only for transcription and efficient translation of IME1, but also for either the activation of Ime1 protein or for the induction/activation of another factor that, either alone or in combination with Ime1, induces meiosis.
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Affiliation(s)
- A Sherman
- Department of Genetics, Hebrew University, Jerusalem, Israel
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76
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Treinin M, Simchen G. Mitochondrial activity is required for the expression of IME1, a regulator of meiosis in yeast. Curr Genet 1993; 23:223-7. [PMID: 8435851 DOI: 10.1007/bf00351500] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Sporulation in the yeast Saccharomyces cerevisiae occurs in diploid cells following starvation for glucose and nitrogen sources. A key gene in the regulation of the meiotic process is IME1. A well-documented fact is that respiration is necessary for sporulation. We now show that respiration is necessary for the expression of IME1. We suggest that glucose repression of meiosis is transduced through its effect on respiration, in a pathway separate from that of adenylyl cyclase.
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Affiliation(s)
- M Treinin
- Department of Genetics, Hebrew University, Jerusalem, Israel
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77
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Heude M, Fabre F. a/alpha-control of DNA repair in the yeast Saccharomyces cerevisiae: genetic and physiological aspects. Genetics 1993; 133:489-98. [PMID: 8454201 PMCID: PMC1205337 DOI: 10.1093/genetics/133.3.489] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
It has long been known that diploid strains of yeast are more resistant to gamma-rays than haploid cells, and that this is in part due to heterozygosity at the mating type (MAT) locus. It is shown here that the genetic control exerted by the MAT genes on DNA repair involves the a1 and alpha 2 genes, in a RME1-independent way. In rad18 diploids, affected in the error-prone repair, the a/alpha effects are of a very large amplitude, after both UV and gamma-rays, and also depends on a1 and alpha 2. The coexpression of a and alpha in rad18 haploids suppresses the sensitivity of a subpopulation corresponding to the G2 phase cells. Related to this, the coexpression of a and alpha in RAD+ haploids depresses UV-induced mutagenesis in G2 cells. For srs2 null diploids, also affected in the error-prone repair pathway, we show that their G1 UV sensitivity, likely due to lethal recombination events, is partly suppressed by MAT homozygosity. Taken together, these results led to the proposal that a1-alpha 2 promotes a channeling of some DNA structures from the mutagenic into the recombinational repair process.
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Affiliation(s)
- M Heude
- Institut Curie-Biologie, Centre Universitaire, Orsay, France
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78
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79
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Su SS, Mitchell AP. Identification of functionally related genes that stimulate early meiotic gene expression in yeast. Genetics 1993; 133:67-77. [PMID: 8417990 PMCID: PMC1205299 DOI: 10.1093/genetics/133.1.67] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Meiosis and spore formation in the yeast Saccharomyces cerevisiae are associated with increased expression of sporulation-specific genes. One of these genes, IME2, encodes a putative protein kinase that is a positive regulator of other sporulation-specific genes. We have isolated mutations that cause reduced expression of an ime2-lacZ fusion gene. We found mutations in IME1, a known positive regultor of IME2, and MCK1, a known positive regulator of IME1. We also isolated recessive mutations in 12 other genes, which we designate RIM (Regulator of IME2) genes. Our analysis indicates that the defects in rim1, rim8, rim9 and rim13 mutants are a consequence of diminished IME1 expression and can be suppressed by expression of IME1 from the heterologous ACT1 promoter. These rim mutations also reduced expression of an ime1-HIS3 fusion, in which the HIS3 gene is expressed from the IME1 promoter, and caused reduced levels of IME1 RNA. Although the rim1, rim8, rim9 and rim13 mutant phenotypes are similar to those of mck1 mutants, we found that the defects in ime2-lacZ expression and sporulation of the mck1 rim double mutants were more severe than either single mutant. In contrast, the defects of the rim rim double mutants were similar to either single mutant. The rim1, rim8, rim9 and rim13 mutants also display slow growth at 17 degrees and share a smooth colony morphology that is not evident in mck1 mutants or isogenic wild-type strains. We suggest that RIM1, RIM8, RIM9 and RIM13 encode functionally related products that act in parallel to MCK1 to stimulate IME1 expression.
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Affiliation(s)
- S S Su
- Institute of Cancer Research, Columbia University, New York, New York 10032
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80
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Honigberg SM, Conicella C, Espositio RE. Commitment to meiosis in Saccharomyces cerevisiae: involvement of the SPO14 gene. Genetics 1992; 130:703-16. [PMID: 1582554 PMCID: PMC1204922 DOI: 10.1093/genetics/130.4.703] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
This paper describes the identification, cloning and phenotypic analysis of SPO14, a new gene required for meiosis and spore formation. Studies of strains carrying a temperature-sensitive mutation or a disruption/duplication allele indicate that spo14 mutants have the unusual property of being able to return to mitotic division, even from the late stages of meiotic development. Early meiotic events, such as DNA replication and intragenic and intergenic recombination, occur normally. In contrast, later meiotic processes are defective in spo14 mutants: the meiosis I division appears to be executed at slightly depressed levels, the meiosis II division is reduced more severely, and no spores are formed. Epistasis tests using mutants defective in recombination or reductional division support these findings. Based on these data, we suggest that the SPO14 gene product is involved in the coordinate induction of late meiotic events and that this induction is responsible for the phenomenon of commitment.
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Affiliation(s)
- S M Honigberg
- Department of Molecular Genetics and Cell Biology, University of Chicago, Illinois 60637
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81
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Nakazawa N, Ashikari T, Goto N, Amachi T, Nakajima R, Harashima S, Oshima Y. Partial restoration of sporulation defect in sake yeasts, kyokai no. 7 and no. 9, by increased dosage of the IME1 gene. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0922-338x(92)90180-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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82
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Riggs CD, Hasenkampf CA. Antibodies directed against a meiosis-specific, chromatin-associated protein identify conserved meiotic epitopes. Chromosoma 1991; 101:92-8. [PMID: 1722747 DOI: 10.1007/bf00357058] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The molecular mechanisms by which meiotic events are regulated are at present unknown. To approach this problem, we have exploited the natural synchrony of Lilium meiocytes to compare the nuclear protein profiles of a variety of stages of meiosis. This approach has facilitated the identification of a number of nuclear proteins that appear and disappear in a stage-specific fashion. Here we report the presence of an abundant nuclear protein that first appears during premeiotic interphase, a period during which the irreversible commitment to meiosis occurs. Antibodies directed against this protein demonstrate its meiosis specificity as well as conservation of the epitope(s) in both mono- and dicotyledonous plant species. Chromatin fractionation studies indicate that this protein, which we have termed meiotin-1, is associated with strings of nucleosomes. Implications for meiotic chromatin packaging and chromosome structure are discussed.
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Affiliation(s)
- C D Riggs
- Department of Botany, University of Toronto, Scarborough College, Ontario, Canada
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83
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Abstract
Previous studies have suggested that the differentiated state of meiosis in yeast is regulated primarily at the transcriptional level. This study reports a case of posttranscriptional regulation of a gene whose product is essential for meiosis. The MER2 gene is transcribed in mitosis as well as meiosis; however, the transcript is spliced efficiently to generate a functional gene product only in meiosis. Meiotic levels of splicing depend on the MER1 gene product, which is also essential for meiosis and which is produced only in meiotic cells. Therefore, at least one of the functions of the MER1 protein is to mediate splicing of the MER2 transcript. Genetic data suggest that the MER1 gene may also be responsible for splicing the transcript of at least one other gene.
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Affiliation(s)
- J A Engebrecht
- Department of Biology, Yale University, New Haven, Connecticut 06511-8112
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84
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Hoekstra MF, DeMaggio AJ, Dhillon N. Genetically identified protein kinases in yeast. II: DNA metabolism and meiosis. Trends Genet 1991; 7:293-7. [PMID: 1763427 DOI: 10.1016/0168-9525(91)90311-d] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Genetic analysis of protein kinases in Saccharomyces cerevisiae has revealed protein phosphorylation as a key regulatory mechanism both in the mitotic cell cycle and in meiosis. This article reviews genetically identified protein kinases that are associated with DNA metabolism and the meiotic pathway.
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Affiliation(s)
- M F Hoekstra
- Molecular Biology and Virology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92186-5800
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85
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Kihara K, Nakamura M, Akada R, Yamashita I. Positive and negative elements upstream of the meiosis-specific glucoamylase gene in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1991; 226:383-92. [PMID: 2038303 DOI: 10.1007/bf00260650] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The SGA1 gene encoding glucoamylase is specifically expressed late in meiotic development of the yeast Saccharomyces cerevisiae. We found that accumulation of both enzyme activity and transcripts was regulated negatively by both nutritional signals and a haploid-specific negative regulator gene of meiosis. RME1, and positively by the inducer genes for meiosis, IME1 and IME2. To study the role of sequences upstream of the SGA1 gene in its expression and regulation, we generated internal deletions in the 5' non-coding region of the gene and chimeric genes with portions of the upstream sequence inserted into a reporter gene. By analyzing the expression of these genes, we have identified both a 19 bp upstream activation sequence (UAS) and a 49 bp negatively regulating element (NRE). The UAS activated transcription with no requirement for heterozygosity at the mating-type locus, but this activation was still under negative control by nutrients. The NRE showed no UAS-like activity but conferred IME2-dependent (or meiosis-specific) expression on a heterologous promoter. These results suggest that meiosis-specific expression of the SGA1 gene is established by a regulatory hierarchy including positive and negative factors, the actions of which are mediated through the two separate upstream regulatory elements, UAS and NRE, respectively. Also, that two independently acting cascades exist for the regulation of SGA1 expression: one transduces both the mating-type and nutritional signals and includes the IME2 product, which acts to relieve the repression through NRE; and another transduces only the nutritional signal independently of the above pathway and inhibits positive factors acting on UAS.
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Affiliation(s)
- K Kihara
- Center for Gene Science, Hiroshima University, Japan
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86
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Affiliation(s)
- J W Dolan
- Department of Microbiology, State University of New York, Stony Brook 11794
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87
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88
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Esposito RE, Dresser M, Breitenbach M. Identifying sporulation genes, visualizing synaptonemal complexes, and large-scale spore and spore wall purification. Methods Enzymol 1991; 194:110-31. [PMID: 2005782 DOI: 10.1016/0076-6879(91)94010-a] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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89
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90
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Kallal LA, Bhattacharyya M, Grove SN, Iannacone RF, Pugh TA, Primerano DA, Clancy MJ. Functional analysis of the sporulation-specific SPR6 gene of Saccharomyces cerevisiae. Curr Genet 1990; 18:293-301. [PMID: 2253272 DOI: 10.1007/bf00318210] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The SPR6 gene of Saccharomyces cerevisiae encodes a moderately abundant RNA that is present at high levels only during sporulation. The gene contains a long open reading frame that could encode a hydrophilic protein approximately 21 kDa in size. This protein is probably produced by the yeast, because the lacZ gene of Escherichia coli is expressed during sporulation when fused to SPR6 in the expected reading frame. SPR6 is inessential for sporulation; mutants that lack SPR6 activity sporulate normally and produce viable ascospores. Nonetheless, the SPR6 gene encodes a function that is relevant to sporulating cells; the wild-type allele can enhance sporulation in strains that are defective for several SPR functions. SPR6 is located on chromosome V, 14.4 centimorgans centromere-distal to MET6.
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Affiliation(s)
- L A Kallal
- Department of Biological Sciences, University of New Orleans, LA 70148
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91
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Abstract
The two regulatory pathways appear to come together at the IME1 gene. It is clearly regulated by mating type and induced by starvation as well. Overexpression of IME1 completely overcomes MAT defects but may not circumvent all nutritional control. Kassir et al. (1988) found that overexpression of IME1 allowed sporulation in the presence of glucose and nitrogen. They also have found a meiotic level of message in temperature-sensitive cdc25 diploids shifted to high temperature in rich medium (Simchen and Kassir, 1989). Smith and Mitchell (1989) found that overexpression of IME1 induced an early meiotic event (recombination) in rich medium, but later meiotic events did not occur (i.e., they detected no spore formation). Mitchell (personal communication) has suggested that the difference may be due to differences in the amount of nitrogen present in the two experiments. Thus, while it is clear that IME1 is a necessary positive regulator of meiosis, responding both to mating type and nutritional conditions, it is not clear if it is sufficient. It is possible that other genes are involved in the response to starvation. One interpretation is that a separate nutritional control is exerted for events starting with meiosis I. Much of the regulatory pathway that allows yeast cells to enter meiosis has been determined. As in the case in many sensory transduction pathways, the initial signal for starvation is not yet known, nor is the nature of the proposed downstream phosphorylated effector. Given the power of yeast molecular genetics, answers to both these questions seem attainable. Another area that remains unclear is the difference between responses to nitrogen starvation versus carbon source. Many of the experiments discussed above do not address this question. The strategies used by yeast may be utilized in the developmental decisions used by other, more complex eukaryotes. Certainly several of the gene products involved in nutritional control in yeast have homologies in mammalian systems. For example, the human H-ras gene can substitute for yeast RAS; the relationship is sufficiently close that dominant Ha-ras mutations that inhibit CDC25 have been found (Powers et al., 1989). Furthermore, these dominant Ha-ras mutations have the appropriate phenotype in mammalian cells, suggesting the presence of a CDC25-like protein. Although the major components of mating type control appear to have been defined, the mechanism of the RME1-IME transcriptional control remains to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- R E Malone
- Department of Biology, University of Iowa, Iowa City 52242
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92
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Abstract
The HOP1 gene in Saccharomyces cerevisiae is important for meiotic chromosomal pairing, because hop1 diploids fail to form synaptonemal complex during meiosis and are defective in crossing over between, but not within, chromosomes. We demonstrate here that the HOP1 gene is transcriptionally regulated during sporulation and that the HOP1 protein is situated along the lengths of meiotic chromosomes. Furthermore, the HOP1 protein contains a Cys2/Cys2 zinc finger motif. A mutation within this motif that changes a cysteine to serine results in the hop1 phenotype, consistent with the possibility that the HOP1 gene product acts in chromosome synapsis by directly interacting with DNA. These observations demonstrate that HOP1 encodes a component of meiotic chromosomes, perhaps serving as a constituent of the synaptonemal complex.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Blotting, Western
- Chromosomes, Fungal/ultrastructure
- DNA-Binding Proteins/genetics
- Gene Expression Regulation, Fungal
- Genes, Fungal
- Genetic Complementation Test
- Meiosis
- Metalloproteins/genetics
- Microscopy, Electron
- Molecular Sequence Data
- RNA, Fungal/genetics
- RNA, Fungal/isolation & purification
- Restriction Mapping
- Saccharomyces cerevisiae/cytology
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/physiology
- Sequence Homology, Nucleic Acid
- Spores, Fungal/physiology
- Transcription, Genetic
- Zinc/metabolism
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93
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Yoshida M, Kawaguchi H, Sakata Y, Kominami K, Hirano M, Shima H, Akada R, Yamashita I. Initiation of meiosis and sporulation in Saccharomyces cerevisiae requires a novel protein kinase homologue. MOLECULAR & GENERAL GENETICS : MGG 1990; 221:176-86. [PMID: 2196430 DOI: 10.1007/bf00261718] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
SME1 was cloned due to its high copy number effect: it enabled MATa/MAT alpha diploid cells to undergo meiosis and sporulation in a vegetative medium. Disruption of SME1 resulted in a recessive Spo- phenotype. These results suggest that SME1 is a positive regulator for meiosis. DNA sequencing analysis revealed an open reading frame of 645 amino acids. An amino terminal peptide of ca 400 amino acids in the deduced protein was similar to known protein kinases. Transcription of SME1 was regulated negatively by nitrogen and glucose and positively by MATa/MAT alpha and IME1, another positive regulator gene of meiosis. By complementation analysis, SME1 was found to be identical to IME2, which had been shown to be important in meiosis. These results suggest that IME1 product stimulates meiosis by activating transcription of SME1 (IME2) and that protein phosphorylation is required for initiation of meiosis.
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Affiliation(s)
- M Yoshida
- Center for Gene Science, Hiroshima University, Higashi-Hiroshima, Japan
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