scholarly journals IME4, a gene that mediates MAT and nutritional control of meiosis in Saccharomyces cerevisiae.

1992 ◽  
Vol 12 (3) ◽  
pp. 1078-1086 ◽  
Author(s):  
J C Shah ◽  
M J Clancy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nutrient Availability ◽  
Cell Types ◽  
Cell Type ◽  
Transcript Accumulation ◽  
Yeast Saccharomyces Cerevisiae ◽  
New Gene ◽  
Low Levels ◽  
Diploid Cells

In the yeast Saccharomyces cerevisiae, sporulation occurs in response to nutritional and genetic signals. The process is initiated when nutrient availability limits mitotic growth, but only in MATa/MAT alpha diploid cells. Under these conditions, the cells express an activator of meiosis (IME1), which is required for the expression of early sporulation-specific genes. We describe a new gene, IME4, whose activity is essential for IME1 transcript accumulation and sporulation. The IME4 transcript was induced in starved MATa/MAT alpha diploids but not in other cell types. In addition, excess IME4 promoted sporulation in mat-insufficient cells. Thus, IME4 appears to activate IME1 in response to cell type and nutritional signals. We have also explored the interactions between IME4 and two genes that are known to regulate IME1 expression. Normally, cells that lack complete MAT information cannot sporulate; when such strains lack RME1 activity or contain the semidominant RES1-1 mutation, however, they can express IME1 and sporulate to low levels. Our results show that mat-insufficient strains containing rme1::LEU2 or RES1-1 bypass mutations still retain MAT control of IME4 expression. Even though IME4 levels remained low, the rme1::LEU2 and RES1-1 mutations allowed IME1 accumulation, implying that these mutations do not require IME4 to exert their effects. In accord with this interpretation, the RES1-1 mutation allowed IME1 accumulation in MATa/MAT alpha strains that contain ime4::LEU2 alleles. These strains still sporulated poorly, suggesting that IME4 plays a role in sporulation in addition to promoting IME1 transcript accumulation. IME4 is located between ADE5 and LYS5 on chromosome VII.

IME4, a gene that mediates MAT and nutritional control of meiosis in Saccharomyces cerevisiae

1992 ◽  
Vol 12 (3) ◽  
pp. 1078-1086
Author(s):  
J C Shah ◽  
M J Clancy
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nutrient Availability ◽  
Cell Types ◽  
Cell Type ◽  
Transcript Accumulation ◽  
Yeast Saccharomyces Cerevisiae ◽  
New Gene ◽  
Low Levels ◽  
Diploid Cells

In the yeast Saccharomyces cerevisiae, sporulation occurs in response to nutritional and genetic signals. The process is initiated when nutrient availability limits mitotic growth, but only in MATa/MAT alpha diploid cells. Under these conditions, the cells express an activator of meiosis (IME1), which is required for the expression of early sporulation-specific genes. We describe a new gene, IME4, whose activity is essential for IME1 transcript accumulation and sporulation. The IME4 transcript was induced in starved MATa/MAT alpha diploids but not in other cell types. In addition, excess IME4 promoted sporulation in mat-insufficient cells. Thus, IME4 appears to activate IME1 in response to cell type and nutritional signals. We have also explored the interactions between IME4 and two genes that are known to regulate IME1 expression. Normally, cells that lack complete MAT information cannot sporulate; when such strains lack RME1 activity or contain the semidominant RES1-1 mutation, however, they can express IME1 and sporulate to low levels. Our results show that mat-insufficient strains containing rme1::LEU2 or RES1-1 bypass mutations still retain MAT control of IME4 expression. Even though IME4 levels remained low, the rme1::LEU2 and RES1-1 mutations allowed IME1 accumulation, implying that these mutations do not require IME4 to exert their effects. In accord with this interpretation, the RES1-1 mutation allowed IME1 accumulation in MATa/MAT alpha strains that contain ime4::LEU2 alleles. These strains still sporulated poorly, suggesting that IME4 plays a role in sporulation in addition to promoting IME1 transcript accumulation. IME4 is located between ADE5 and LYS5 on chromosome VII.

scholarly journals Pheromones and pheromone receptors are the primary determinants of mating specificity in the yeast Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 463-476 ◽  
Author(s):  
A Bender ◽  
G F Sprague
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Types ◽  
Haploid Cell ◽  
Wild Type ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
A Cells ◽  
Alpha Factor ◽  
A Cell ◽  
Specific Proteins

Abstract Saccharomyces cerevisiae has two haploid cell types, a and alpha, each of which produces a unique set of proteins that participate in the mating process. We sought to determine the minimum set of proteins that must be expressed to allow mating and to confer specificity. We show that the capacity to synthesize alpha-factor pheromone and a-factor receptor is sufficient to allow mating by mat alpha 1 mutants, mutants that normally do not express any alpha- or a-specific products. Likewise, the capacity to synthesize a-factor receptor and alpha-factor pheromone is sufficient to allow a ste2 ste6 mutants, which do not produce the normal a cell pheromone and receptor, to mate with wild-type a cells. Thus, the a-factor receptor and alpha-factor pheromone constitute the minimum set of alpha-specific proteins that must be produced to allow mating as an alpha cell. Further evidence that the pheromones and pheromone receptors are important determinants of mating specificity comes from studies with mat alpha 2 mutants, cells that simultaneously express both pheromones and both receptors. We created a series of strains that express different combinations of pheromones and receptors in a mat alpha 2 background. These constructions reveal that mat alpha 2 mutants can be made to mate as either a cells or as alpha cells by causing them to express only the pheromone and receptor set appropriate for a particular cell type. Moreover, these studies show that the inability of mat alpha 2 mutants to respond to either pheromone is a consequence of two phenomena: adaptation to an autocrine response to the pheromones they secrete and interference with response to alpha factor by the a-factor receptor.

scholarly journals Molecular cloning and characterization of the STE7 and STE11 genes of Saccharomyces cerevisiae.

1985 ◽  
Vol 5 (8) ◽  
pp. 1878-1886 ◽  
Author(s):  
D T Chaleff ◽  
K Tatchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Cloning ◽  
Mating Type ◽  
Cell Types ◽  
Transcriptional Level ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genetic Techniques ◽  
Conjugation Process ◽  
Mat Locus

In the yeast Saccharomyces cerevisiae, haploid cells occur in one of the two cell types, a or alpha. The allele present at the mating type (MAT) locus plays a prominent role in the control of cell type expression. An important consequence of the elaboration of cell type is the ability of cells of one mating type to conjugate with cells of the opposite mating type, resulting in yet a third cell type, an a/alpha diploid. Numerous genes that are involved in the expression of cell type and the conjugation process have been identified by standard genetic techniques. Molecular analysis has shown that expression of several of these genes is subject to control on the transcriptional level by the MAT locus. Two genes, STE7 and STE11, are required for mating in both haploid cell types; ste7 and ste11 mutants are sterile. We report here the molecular cloning of STE7 and STE11 genes and show that expression of these genes is not regulated transcriptionally by the MAT locus. We also have genetically mapped the STE11 gene to chromosome XII, 40 centimorgans from ura4.

scholarly journals Saccharomyces cerevisiae exhibits a sporulation-specific temporal pattern of transcript accumulation.

1985 ◽  
Vol 5 (4) ◽  
pp. 751-761 ◽  
Author(s):  
D B Kaback ◽  
L R Feldberg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Specific Pattern ◽  
Transcript Accumulation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Vegetative Cells ◽  
Activation Of Transcription ◽  
Nonfermentable Carbon Source ◽  
General Activation ◽  
Diploid Cells

Cultures of the yeast Saccharomyces cerevisiae that are heterozygous for the mating type (MATa/MAT alpha) undergo synchronous meiosis and spore formation when starved for nitrogen and supplied with a nonfermentable carbon source such as acetate. Haploid and homozygous MAT alpha/MAT alpha and MATa/MATa diploid cells incubated under the same conditions fail to undergo meiosis and are asporogenous. It has not yet been firmly established that gene expression during sporulation is controlled at the level of transcript accumulation. To examine this question, we used cloned genes that encode a variety of "housekeeping" functions to probe Northern blots to assay the appearance of specific transcripts in both sporulating and asporogenous S. cerevisiae. In sporulating cells, each transcript showed a characteristic pattern of accumulation, reaching a maximum relative abundance at one of several different periods. In contrast, in both asporogenous haploid MATa and diploid MAT alpha/MAT alpha cells, all transcripts accumulated with similar kinetics. These results suggest a sporulation-specific pattern for transcript appearance. During these studies, high levels of several different transcripts were observed at unexpected times in sporulating cells. Histone (H)2A and (H)2B1 transcripts, although most abundant during premeiotic DNA synthesis, remained at one-third to one-half maximal levels after its end and were found in mature ascospores. Their appearance at this time is in sharp contrast to vegetative cells in which these histone transcripts are only found just before and during the period of DNA synthesis. Furthermore, transcripts from GAL10 and CDC10 genes, which are believed to be dispensable for sporulation, were much more abundant in sporulating cells than in asporogenous cells and vegetative cells grown on glucose or acetate. The presence of these transcripts did not appear to be due to a general activation of transcription because each accumulated with different kinetics. In addition, the transcript for at least one gene, HO, that is also dispensable for sporulation was not detected. The increased abundance of transcripts from some genes not required for sporulation leads us to propose that genes preferentially expressed during sporulation need not be essential for this differentiation.

scholarly journals An Ssn6-Tup1-dependent negative regulatory element controls sporulation-specific expression of DIT1 and DIT2 in Saccharomyces cerevisiae.

1997 ◽  
Vol 17 (1) ◽  
pp. 123-134 ◽  
Author(s):  
H Friesen ◽  
S R Hepworth ◽  
J Segall
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Reporter Gene ◽  
Regulatory Element ◽  
Tata Box ◽  
Transcript Accumulation ◽  
Independent Manner ◽  
Yeast Saccharomyces Cerevisiae ◽  
Specific Expression ◽  
Negative Regulatory Element ◽  
Diploid Cells

Sporulation of the yeast Saccharomyces cerevisiae is a process of cellular differentiation that occurs in MATa/MAT alpha diploid cells in response to starvation. The sporulation-specific genes DIT1 and DIT2, which are required for spore wall formation, are activated midway through the sporulation program, with maximal transcript accumulation occurring at the time of prospore enclosure. In this study, we have identified a negative regulatory element, termed NREDIT, that is located between the start sites of transcription of these divergently transcribed genes. This element, which prevents expression of the DIT1 and DIT2 genes during vegetative growth, reduces expression of a CYC1-lacZ reporter gene more than 1,000-fold and acts in an orientation- and position-independent manner. We found that the ability of NREDIT to turn of expression of the reporter gene and the chromosomal DIT1 and DIT2 genes in vegetative cells requires the Ssn6-Tup1 repression complex. Interestingly, NREDIT-mediated repression of the reporter gene is maintained during sporulation. Derepression during sporulation requires complex interactions among several cis-acting elements. These are present on an approximately 350-bp DNA fragment extending from NREDIT to the TATA box and an approximately 125-bp fragment spanning the TATA box of DIT1. Additionally, a region of NREDIT which is very similar in sequence to UASSPS4, an element that activates gene expression midway through sporulation, contributes both to vegetative repression and to sporulation-specific induction of DIT1. We propose a model to explain the requirement for multiple elements in overcoming NREDIT-mediated repression during sporulation.

Molecular cloning and characterization of the STE7 and STE11 genes of Saccharomyces cerevisiae

1985 ◽  
Vol 5 (8) ◽  
pp. 1878-1886
Author(s):  
D T Chaleff ◽  
K Tatchell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Cloning ◽  
Mating Type ◽  
Cell Types ◽  
Transcriptional Level ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genetic Techniques ◽  
Conjugation Process ◽  
Mat Locus

In the yeast Saccharomyces cerevisiae, haploid cells occur in one of the two cell types, a or alpha. The allele present at the mating type (MAT) locus plays a prominent role in the control of cell type expression. An important consequence of the elaboration of cell type is the ability of cells of one mating type to conjugate with cells of the opposite mating type, resulting in yet a third cell type, an a/alpha diploid. Numerous genes that are involved in the expression of cell type and the conjugation process have been identified by standard genetic techniques. Molecular analysis has shown that expression of several of these genes is subject to control on the transcriptional level by the MAT locus. Two genes, STE7 and STE11, are required for mating in both haploid cell types; ste7 and ste11 mutants are sterile. We report here the molecular cloning of STE7 and STE11 genes and show that expression of these genes is not regulated transcriptionally by the MAT locus. We also have genetically mapped the STE11 gene to chromosome XII, 40 centimorgans from ura4.

scholarly journals Selection for early meiotic mutants in yeast.

Genetics ◽  
1992 ◽  
Vol 131 (1) ◽  
pp. 65-72 ◽  
Author(s):  
A P Mitchell ◽  
K S Bowdish
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Alpha Cells ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Meiotic Mutants ◽  
Recessive Mutations ◽  
Lethal Damage ◽  
Selection For ◽  
Diploid Cells

Abstract In the yeast Saccharomyces cerevisiae, only a/alpha cells can enter meiosis; a and alpha cells cannot. Because a/alpha cells are typically diploid and a and alpha cells are typically haploid, this cell type restriction ensures that only diploid cells enter meiosis. Entry into meiosis is accompanied by an increase in expression of the IME1 gene; the IME1 product (IME1) then activates IME2 and other meiotic genes. We have found that IME1 expression is toxic to starved haploid cells, presumably because IME1 directs them into meiosis. IME1 toxicity is greater in rad52 mutants, in which meiotic recombination causes lethal damage. Suppressors of IME1 toxicity include recessive mutations in two genes, RIM11 and RIM16 (Regulator of Inducer of Meiosis), that are required for IME1 to activate IME2 expression. RIM11 maps near CIN4 on chromosome XIII.

Saccharomyces cerevisiae exhibits a sporulation-specific temporal pattern of transcript accumulation

1985 ◽  
Vol 5 (4) ◽  
pp. 751-761
Author(s):  
D B Kaback ◽  
L R Feldberg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Specific Pattern ◽  
Transcript Accumulation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Vegetative Cells ◽  
Activation Of Transcription ◽  
Nonfermentable Carbon Source ◽  
General Activation ◽  
Diploid Cells

Cultures of the yeast Saccharomyces cerevisiae that are heterozygous for the mating type (MATa/MAT alpha) undergo synchronous meiosis and spore formation when starved for nitrogen and supplied with a nonfermentable carbon source such as acetate. Haploid and homozygous MAT alpha/MAT alpha and MATa/MATa diploid cells incubated under the same conditions fail to undergo meiosis and are asporogenous. It has not yet been firmly established that gene expression during sporulation is controlled at the level of transcript accumulation. To examine this question, we used cloned genes that encode a variety of "housekeeping" functions to probe Northern blots to assay the appearance of specific transcripts in both sporulating and asporogenous S. cerevisiae. In sporulating cells, each transcript showed a characteristic pattern of accumulation, reaching a maximum relative abundance at one of several different periods. In contrast, in both asporogenous haploid MATa and diploid MAT alpha/MAT alpha cells, all transcripts accumulated with similar kinetics. These results suggest a sporulation-specific pattern for transcript appearance. During these studies, high levels of several different transcripts were observed at unexpected times in sporulating cells. Histone (H)2A and (H)2B1 transcripts, although most abundant during premeiotic DNA synthesis, remained at one-third to one-half maximal levels after its end and were found in mature ascospores. Their appearance at this time is in sharp contrast to vegetative cells in which these histone transcripts are only found just before and during the period of DNA synthesis. Furthermore, transcripts from GAL10 and CDC10 genes, which are believed to be dispensable for sporulation, were much more abundant in sporulating cells than in asporogenous cells and vegetative cells grown on glucose or acetate. The presence of these transcripts did not appear to be due to a general activation of transcription because each accumulated with different kinetics. In addition, the transcript for at least one gene, HO, that is also dispensable for sporulation was not detected. The increased abundance of transcripts from some genes not required for sporulation leads us to propose that genes preferentially expressed during sporulation need not be essential for this differentiation.

scholarly journals A NEW GENE AFFECTING THE EFFICIENCY OF MATING-TYPE INTERCONVERSIONS IN HOMOTHALLIC STRAINS OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1977 ◽  
Vol 87 (1) ◽  
pp. 33-50
Author(s):  
James E Haber ◽  
Barbara Garvik
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Genetic Locus ◽  
Cell Types ◽  
Mating Types ◽  
Type Locus ◽  
New Gene ◽  
Unequal Number ◽  
Original Cell ◽  
Diploid Cells

ABSTRACT Homothallic strains of Saccharomyes cerevisiae are able to switch efficiently from one mating genotype to another. From a single haploid spore arise both a and α mating type cells, which then self-mate to produce a colony consisting almost exclusively of nonmating a/α diploid cells. We have isolated a mutant homothallic strain that gives rise to colonies that show bisexual mating behavior. The mating reaction is always asymmetric, that is, in some colonies a mating is much stronger than α mating, while others show greater α than a mating.—This mating phenotype arises from the presence of three cell types in a colony: some a/α nonmating diploids and an unequal number of a and α haploid cells. The predominant haploid type is that of the original cell that gives rise to the colony. This mixture of cell types arises from a very reduced efficiency of homothallic mating-type interconversions in the mutant strain.—The mutation, designated switch (swi1-1), behaves as a single genetic locus. The mutation is centromere linked, but not linked to the mating type locus or to any of the homothallism genes: HO, HM  a and HMα. The switch mutation does not affect the efficiency of self-mating, but rather directly affects the frequency of interconversion of mating types.

scholarly journals The Spindle Checkpoint of the Yeast Saccharomyces cerevisiae Requires Kinetochore Function and Maps to the CBF3 Domain

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1493-1502
Author(s):  
Richard D Gardner ◽  
Atasi Poddar ◽  
Chris Yellman ◽  
Penny A Tavormina ◽  
M Cristina Monteagudo ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Critical Role ◽  
Spindle Checkpoint ◽  
Essential Genes ◽  
Gene Fusions ◽  
Yeast Saccharomyces Cerevisiae ◽  
Checkpoint Signaling ◽  
One Step ◽  
Diploid Cells ◽  
Kinetochore Function

Abstract We have measured the activity of the spindle checkpoint in null mutants lacking kinetochore activity in the yeast Saccharomyces cerevisiae. We constructed deletion mutants for nonessential genes by one-step gene replacements. We constructed heterozygous deletions of one copy of essential genes in diploid cells and purified spores containing the deletion allele. In addition, we made gene fusions for three essential genes to target the encoded proteins for proteolysis (degron alleles). We determined that Ndc10p, Ctf13p, and Cep3p are required for checkpoint activity. In contrast, cells lacking Cbf1p, Ctf19p, Mcm21p, Slk19p, Cse4p, Mif2p, Mck1p, and Kar3p are checkpoint proficient. We conclude that the kinetochore plays a critical role in checkpoint signaling in S. cerevisiae. Spindle checkpoint activity maps to a discreet domain within the kinetochore and depends on the CBF3 protein complex.

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