scholarly journals Identification of new genes required for meiotic recombination in Saccharomyces cerevisiae.

Genetics ◽  
1993 ◽  
Vol 133 (1) ◽  
pp. 51-66 ◽  
Author(s):  
M Ajimura ◽  
S H Leem ◽  
H Ogawa
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Specific Gene ◽  
Early Step ◽  
Haploid Strain ◽  
New Genes ◽  
Intragenic Complementation ◽  
Complementation Groups ◽  
Chromosome Iii ◽  
Unusual Phenotype

Abstract Mutants defective in meiotic recombination were isolated from a disomic haploid strain of Saccharomyces cerevisiae by examining recombination within the leu2 and his4 heteroalleles located on chromosome III. The mutants were classified into two new complementation groups (MRE2 and MRE11) and eight previously identified groups, which include SPO11, HOP1, REC114, MRE4/MEK1 and genes in the RAD52 epistasis group. All of the mutants, in which the mutations in the new complementation groups are homozygous and diploid, can undergo premeiotic DNA synthesis and produce spores. The spores are, however, not viable. The mre2 and mre11 mutants produce viable spores in a spo13 background, in which meiosis I is bypassed, suggesting that these mutants are blocked at an early step in meiotic recombination. The mre2 mutant does not exhibit any unusual phenotype during mitosis and it is, thus, considered to have a mutation in a meiosis-specific gene. By contrast, the mre11 mutant is sensitive to damage to DNA by methyl methanesulfonate and exhibits a hyperrecombination phenotype in mitosis. Among six alleles of HOP1 that were isolated, an unusual pattern of intragenic complementation was observed.

scholarly journals TETRAPLOID STRAINS OF SACCHAROMYCES CEREVISIAE THAT ARE TRISOMIC FOR CHROMOSOME III

Genetics ◽  
1978 ◽  
Vol 89 (4) ◽  
pp. 667-684
Author(s):  
Michael I Riley ◽  
T R Manney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Computer Simulation ◽  
Meiotic Recombination ◽  
Meiotic Segregation ◽  
Segregation Data ◽  
Strong Interference ◽  
Chromosome Iii ◽  
Double Crossovers

ABSTRACT Meiotic segregation of several genes has been studied in tetraploid strains that are trisomic for chromosome III. The segregation data were compared to a computer simulation that assumes trivalent pairing of homologues involved in exchanges, followed by nonpreferential segregation. Trivalent pairing was characterized by higher frequencies of exchange as compared to bivalent pairing, and by the presence of spores resulting from at least double crossovers involving all three homologues. Trivalent segregation was characterized by a unique recombinant class. The strong interference normally exhibited in diploid meiotic recombination was not evident from the frequency of double crossovers in these strains.

Positive control of sporulation-specific genes by the IME1 and IME2 products in Saccharomyces cerevisiae

1990 ◽  
Vol 10 (5) ◽  
pp. 2104-2110
Author(s):  
A P Mitchell ◽  
S E Driscoll ◽  
H E Smith
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Positive Control ◽  
Spore Formation ◽  
Specific Gene ◽  
Heterologous Promoter ◽  
Yeast Saccharomyces Cerevisiae ◽  
Specific Gene Expression ◽  
Rapid Induction

In the yeast Saccharomyces cerevisiae, meiosis and spore formation require the induction of sporulation-specific genes. Two genes are thought to activate the sporulation program: IME1 and IME2 (inducer of meiosis). Both genes are induced upon entry into meiosis, and IME1 is required for IME2 expression. We report here that IME1 is essential for expression of four sporulation-specific genes. In contrast, IME2 is not absolutely essential for expression of the sporulation-specific genes, but contributes to their rapid induction. Expression of IME2 from a heterologous promoter permits the expression of these sporulation-specific genes, meiotic recombination, and spore formation in the absence of IME1. We propose that the IME1 and IME2 products can each activate sporulation-specific genes independently. In addition, the IME1 product stimulates sporulation-specific gene expression indirectly through activation of IME2 expression.

scholarly journals NDT80 and the Meiotic Recombination Checkpoint Regulate Expression of Middle Sporulation-Specific Genes in Saccharomyces cerevisiae

1998 ◽  
Vol 18 (10) ◽  
pp. 5750-5761 ◽  
Author(s):  
Shelley R. Hepworth ◽  
Helena Friesen ◽  
Jacqueline Segall
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Active Form ◽  
Specific Gene ◽  
Subsequent Generation ◽  
Genes Encoding ◽  
Recombination Checkpoint ◽  
Sporulation Genes ◽  
Meiosis I

ABSTRACT Distinct classes of sporulation-specific genes are sequentially expressed during the process of spore formation in Saccharomyces cerevisiae. The transition from expression of early meiotic genes to expression of middle sporulation-specific genes occurs at about the time that cells exit from pachytene and form the meiosis I spindle. To identify genes encoding potential regulators of middle sporulation-specific gene expression, we screened for mutants that expressed early meiotic genes but failed to express middle sporulation-specific genes. We identified mutant alleles ofRPD3, SIN3, and NDT80 in this screen. Rpd3p, a histone deacetylase, and Sin3p are global modulators of gene expression. Ndt80p promotes entry into the meiotic divisions. We found that entry into the meiotic divisions was not required for activation of middle sporulation genes; these genes were efficiently expressed in a clb1 clb3 clb4 strain, which fails to enter the meiotic divisions due to reduced Clb-dependent activation of Cdc28p kinase. In contrast, middle sporulation genes were not expressed in a dmc1 strain, which fails to enter the meiotic divisions because a defect in meiotic recombination leads to aRAD17-dependent checkpoint arrest. Expression of middle sporulation genes, as well as entry into the meiotic divisions, was restored to a dmc1 strain by mutation of RAD17. Our studies also revealed that NDT80 was a temporally distinct, pre-middle sporulation gene and that its expression was reduced, but not abolished, on mutation of DMC1,RPD3, SIN3, or NDT80 itself. In summary, our data indicate that Ndt80p is required for expression of middle sporulation genes and that the activity of Ndt80p is controlled by the meiotic recombination checkpoint. Thus, middle genes are expressed only on completion of meiotic recombination and subsequent generation of an active form of Ndt80p.

scholarly journals Isolation and genetic analysis of Saccharomyces cerevisiae mutants supersensitive to G1 arrest by a factor and alpha factor pheromones.

1982 ◽  
Vol 2 (1) ◽  
pp. 11-20 ◽  
Author(s):  
R K Chan ◽  
C A Otte
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Solid Medium ◽  
G1 Arrest ◽  
Alpha Cells ◽  
Opposite Mating Type ◽  
Alpha Factor ◽  
Complementation Groups ◽  
Chromosome Iii ◽  
The Right

Eight independently isolated mutants which are supersensitive (Sst-) to the G1 arrest induced by the tridecapeptide pheromone alpha factor were identified by screening mutagenized Saccharomyces cerevisiae MATa cells on solid medium for increased growth inhibition by alpha factor. These mutants carried lesions in two complementation groups, sst1 and sst2. Mutations at the sst1 locus were mating type specific: MATa sst1 cells were supersensitive to alpha factor, but MAT alpha sst1 cells were not supersensitive to a factor. In contrast, mutations at the sst2 locus conferred supersensitivity to the pheromones of the opposite mating type on both MATa and MAT alpha cells. Even in the absence of added alpha pheromone, about 10% of the cells in exponentially growing cultures of MATa strains carrying any of three different alleles of sst2 (including the ochre mutation sst2-4) had the aberrant morphology ("shmoo" shape) that normally develops only after MATa cells are exposed to alpha factor. This "self-shmooing" phenotype was genetically linked to the sst2 mutations, although the leakiest allele isolated (sst2-3) did not display this characteristic. Normal MATa/MAT alpha diploids do not respond to pheromones; diploids homozygous for an sst2 mutation (MATa/MAT alpha sst2-1/sst2-1) were still insensitive to alpha factor. The sst1 gene was mapped to within 6.9 centimorgans of his6 on chromosome IX. The sst2 gene was unlinked to sst1, was not centromere linked, and was shown to be neither linked to nor centromere distal to MAT on the right arm of chromosome III.

Isolation and genetic analysis of Saccharomyces cerevisiae mutants supersensitive to G1 arrest by a factor and alpha factor pheromones

1982 ◽  
Vol 2 (1) ◽  
pp. 11-20
Author(s):  
R K Chan ◽  
C A Otte
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Solid Medium ◽  
G1 Arrest ◽  
Alpha Cells ◽  
Opposite Mating Type ◽  
Alpha Factor ◽  
Complementation Groups ◽  
Chromosome Iii ◽  
The Right

Eight independently isolated mutants which are supersensitive (Sst-) to the G1 arrest induced by the tridecapeptide pheromone alpha factor were identified by screening mutagenized Saccharomyces cerevisiae MATa cells on solid medium for increased growth inhibition by alpha factor. These mutants carried lesions in two complementation groups, sst1 and sst2. Mutations at the sst1 locus were mating type specific: MATa sst1 cells were supersensitive to alpha factor, but MAT alpha sst1 cells were not supersensitive to a factor. In contrast, mutations at the sst2 locus conferred supersensitivity to the pheromones of the opposite mating type on both MATa and MAT alpha cells. Even in the absence of added alpha pheromone, about 10% of the cells in exponentially growing cultures of MATa strains carrying any of three different alleles of sst2 (including the ochre mutation sst2-4) had the aberrant morphology ("shmoo" shape) that normally develops only after MATa cells are exposed to alpha factor. This "self-shmooing" phenotype was genetically linked to the sst2 mutations, although the leakiest allele isolated (sst2-3) did not display this characteristic. Normal MATa/MAT alpha diploids do not respond to pheromones; diploids homozygous for an sst2 mutation (MATa/MAT alpha sst2-1/sst2-1) were still insensitive to alpha factor. The sst1 gene was mapped to within 6.9 centimorgans of his6 on chromosome IX. The sst2 gene was unlinked to sst1, was not centromere linked, and was shown to be neither linked to nor centromere distal to MAT on the right arm of chromosome III.

scholarly journals Positive control of sporulation-specific genes by the IME1 and IME2 products in Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (5) ◽  
pp. 2104-2110 ◽  
Author(s):  
A P Mitchell ◽  
S E Driscoll ◽  
H E Smith
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Positive Control ◽  
Spore Formation ◽  
Specific Gene ◽  
Heterologous Promoter ◽  
Yeast Saccharomyces Cerevisiae ◽  
Specific Gene Expression ◽  
Rapid Induction

In the yeast Saccharomyces cerevisiae, meiosis and spore formation require the induction of sporulation-specific genes. Two genes are thought to activate the sporulation program: IME1 and IME2 (inducer of meiosis). Both genes are induced upon entry into meiosis, and IME1 is required for IME2 expression. We report here that IME1 is essential for expression of four sporulation-specific genes. In contrast, IME2 is not absolutely essential for expression of the sporulation-specific genes, but contributes to their rapid induction. Expression of IME2 from a heterologous promoter permits the expression of these sporulation-specific genes, meiotic recombination, and spore formation in the absence of IME1. We propose that the IME1 and IME2 products can each activate sporulation-specific genes independently. In addition, the IME1 product stimulates sporulation-specific gene expression indirectly through activation of IME2 expression.

scholarly journals Stimulation of meiotic recombination in yeast by an ARS element.

Genetics ◽  
1993 ◽  
Vol 134 (1) ◽  
pp. 175-188
Author(s):  
A J Rattray ◽  
L S Symington
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Meiotic Recombination ◽  
Replication Origin ◽  
Chromosome Iii ◽  
Gene Conversions ◽  
Stimulation Of

Abstract In a previous study, meiotic recombination events were monitored in the 22-kb LEU2 to CEN3 region of chromosome III of Saccharomyces cerevisiae. One region (the hotspot) was shown to have an enhanced level of both gene conversion events and reciprocal crossovers, whereas a second region (the coldspot) was shown to have a depressed level of both types of recombination events. In this study we have analyzed the effects of a replication origin, ARS307, located about 2 kb centromere proximal to the hotspot region, on the distribution of meiotic recombination events. We find that a deletion of this origin results in a reduction of both gene conversions and reciprocal crossovers in the hotspot region, and that a 200-bp fragment of this ARS element can stimulate both types of recombination events when relocated to the coldspot region. Although the magnitude of stimulation of these events is similar in both orientations, whether the ARS is functional or not, the distribution of events is dependent upon the orientation of the element.

scholarly journals RECESSIVE UAA SUPPRESSORS OF THE YEAST SACCHAROMYCES CEREVISIAE

Genetics ◽  
1982 ◽  
Vol 102 (4) ◽  
pp. 653-664
Author(s):  
Bun-Ichiro Ono ◽  
Mitsuaki Tanaka ◽  
Masayo Kominami ◽  
Yumiko Ishino ◽  
Sumio Shinoda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Yeast Saccharomyces Cerevisiae ◽  
Haploid Strain ◽  
High Incidence ◽  
Complementation Groups

ABSTRACT Recessive lysine-independent revertants were isolated from a ψ+ haploid strain of the yeast Saccharomyces cerevisiae containing one of the leucine-inserting UAA suppressors, SUP29, and various UAA mutations including lys1-1. The majority of the revertants were found to have recessive suppressors in addition to the pre-existing SUP29 mutation. The recessive suppressors were able to suppress only a very limited number of UAA mutations, and none of the UAG mutations thus far examined. The recessive inefficient UAA suppressors were assigned to three complementation groups, sup111, sup112, and sup113. A high incidence of gene conversion was observed for an allele of sup111. An antisuppressor acting on sup111, but not detectably on SUP29, was inadvertently obtained during the course of the study. Interactions between SUP29, sup111 and the antisuppressor asu12 were studied.

scholarly journals Multiple new genes that determine activity for the first step of leucine biosynthesis in Saccharomyces cerevisiae.

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 13-20 ◽  
Author(s):  
P Drain ◽  
P Schimmel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Wild Type ◽  
Leucine Biosynthesis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Multiple Components ◽  
New Genes ◽  
Yeast Strains ◽  
Complementation Groups ◽  
Or Genes ◽  
New Mutations

Abstract The first step in the biosynthesis of leucine is catalyzed by alpha-isopropylmalate (alpha-IPM) synthase. In the yeast Saccharomyces cerevisiae, LEU4 encodes the isozyme responsible for the majority of alpha-IPM synthase activity. Yeast strains that bear disruption alleles of LEU4, however, are Leu+ and exhibit a level of synthase activity that is 20% of the wild type. To identify the gene or genes that encode this remaining activity, a leu4 disruption strain was mutagenized. The mutations identified define three new complementation groups, designated leu6, leu7 and leu8. Each of these new mutations effect leucine auxotrophy only if a leu4 mutation is present and each results in loss of alpha-IPM synthase activity. Further analysis suggests that LEU7 and LEU8 are candidates for the gene or genes that encode an alpha-IPM synthase activity. The results demonstrate that multiple components determine the residual alpha-IPM synthase activity in leu4 gene disruption strains of S. cerevisiae.

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