scholarly journals MATING-TYPE REGULATION OF METHYL METHANESULFONATE SENSITIVITY IN SACCHAROMYCES CEREVISIAE

Genetics ◽  
1980 ◽  
Vol 95 (2) ◽  
pp. 259-271
Author(s):  
George P Livi ◽  
Vivian L Mackay
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
S Phase ◽  
Methyl Methanesulfonate ◽  
Survival Curves ◽  
Repair Capacity ◽  
Type Locus ◽  
X Ray ◽  
G2 Phase ◽  
Diploid Cells

ABSTRACT Heterozygosity at the mating-type locus (MAT) in Saccharomyces cerevisiae has been shown previously to enhance X-ray survival in diploid cells. We now show that a/α diploids are also more resistant to the radiomimetic agent methyl methanesulfonate (MMS) that are diploids that are homozygous at MAT (i.e., either a/a or α/α). Log-phase a/α cultures exhibit biphasic MMS survival curves, in which the more resistant fraction consists of budded cells (those cells in the S and G2 phases of the cell cycle). Survival curves for log-phase cultures of a/a or α/α diploids have little if any biphasic nature, suggesting that the enhanced S- and G2-phase repair capacity of a/α cells may be associated with heterozygosity at MAT. The survival of cells arrested at the beginning of the S phase with hydroxyurea indicates that MAT-dependent MMS repair is limited to S and G2, whereas MAT-independent repair can occur in Gl.

Regulation of STA1 gene expression by MAT during the life cycle of Saccharomyces cerevisiae

1989 ◽  
Vol 9 (9) ◽  
pp. 3992-3998
Author(s):  
A M Dranginis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Yeast Cells ◽  
Specific Gene ◽  
Activity Levels ◽  
Sporulation Medium ◽  
Mrna Levels ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Diploid Cells

STA1 encodes a secreted glucoamylase of the yeast Saccharomyces cerevisiae var. diastaticus. Glucoamylase secretion is controlled by the mating type locus MAT; a and alpha haploid yeast cells secrete high levels of the enzyme, but a/alpha diploid cells produce undetectable amounts. It has been suggested that STA1 is regulated by MATa2 (I. Yamashita, Y. Takano, and S. Fukui, J. Bacteriol. 164:769-773, 1985), which is a MAT transcript of previously unknown function. In contrast, this work shows that deletion of the entire MATa2 gene had no effect on STA1 regulation but that deletion of MATa1 sequences completely abolished mating-type control. In all cases, glucoamylase activity levels reflected STA1 mRNA levels. It appears that STA1 is a haploid-specific gene that is regulated by MATa1 and a product of the MAT alpha locus and that this regulation occurs at the level of RNA accumulation. STA1 expression was also shown to be glucose repressible. STA1 mRNA was induced in diploids during sporulation along with SGA, a closely linked gene that encodes an intracellular sporulation-specific glucoamylase of S. cerevisiae. A diploid strain with a MATa1 deletion showed normal induction of STA1 in sporulation medium, but SGA expression was abolished. Therefore, these two homologous and closely linked glucoamylase genes are induced by different mechanisms during sporulation. STA1 induction may be a response to the starvation conditions necessary for sporulation, while SGA induction is governed by the pathway by which MAT regulates sporulation. The strain containing a complete deletion of MATa2 grew, mated, and sporulated normally.

Transcriptional control of the sporulation-specific glucoamylase gene in the yeast Saccharomyces cerevisiae

1985 ◽  
Vol 5 (11) ◽  
pp. 3069-3073
Author(s):  
I Yamashita ◽  
S Fukui
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Transcriptional Control ◽  
Northern Blot Analysis ◽  
Insertion Mutation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Mating Type Genes ◽  
Diploid Cells ◽  
Glucoamylase Gene

In the yeast Saccharomyces cerevisiae, glucoamylase activity appears specifically in sporulating cells heterozygous for the mating-type locus (MAT). We identified a sporulation-specific glucoamylase gene (SGA) and show that expression of SGA is positively regulated by the mating-type genes, both MATa1 and MAT alpha 2. Northern blot analysis revealed that control of SGA is exerted at the level of RNA production. Expression of SGA or the consequent degradation of glycogen to glucose in cells is not required for meiosis or sporulation, since MATa/MAT alpha diploid cells homozygous for an insertion mutation at SGA still formed four viable ascospores.

scholarly journals Regulation of STA1 gene expression by MAT during the life cycle of Saccharomyces cerevisiae.

1989 ◽  
Vol 9 (9) ◽  
pp. 3992-3998 ◽  
Author(s):  
A M Dranginis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Yeast Cells ◽  
Specific Gene ◽  
Activity Levels ◽  
Sporulation Medium ◽  
Mrna Levels ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Diploid Cells

STA1 encodes a secreted glucoamylase of the yeast Saccharomyces cerevisiae var. diastaticus. Glucoamylase secretion is controlled by the mating type locus MAT; a and alpha haploid yeast cells secrete high levels of the enzyme, but a/alpha diploid cells produce undetectable amounts. It has been suggested that STA1 is regulated by MATa2 (I. Yamashita, Y. Takano, and S. Fukui, J. Bacteriol. 164:769-773, 1985), which is a MAT transcript of previously unknown function. In contrast, this work shows that deletion of the entire MATa2 gene had no effect on STA1 regulation but that deletion of MATa1 sequences completely abolished mating-type control. In all cases, glucoamylase activity levels reflected STA1 mRNA levels. It appears that STA1 is a haploid-specific gene that is regulated by MATa1 and a product of the MAT alpha locus and that this regulation occurs at the level of RNA accumulation. STA1 expression was also shown to be glucose repressible. STA1 mRNA was induced in diploids during sporulation along with SGA, a closely linked gene that encodes an intracellular sporulation-specific glucoamylase of S. cerevisiae. A diploid strain with a MATa1 deletion showed normal induction of STA1 in sporulation medium, but SGA expression was abolished. Therefore, these two homologous and closely linked glucoamylase genes are induced by different mechanisms during sporulation. STA1 induction may be a response to the starvation conditions necessary for sporulation, while SGA induction is governed by the pathway by which MAT regulates sporulation. The strain containing a complete deletion of MATa2 grew, mated, and sporulated normally.

scholarly journals Transcriptional control of the sporulation-specific glucoamylase gene in the yeast Saccharomyces cerevisiae.

1985 ◽  
Vol 5 (11) ◽  
pp. 3069-3073 ◽  
Author(s):  
I Yamashita ◽  
S Fukui
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Transcriptional Control ◽  
Northern Blot Analysis ◽  
Insertion Mutation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Mating Type Genes ◽  
Diploid Cells ◽  
Glucoamylase Gene

In the yeast Saccharomyces cerevisiae, glucoamylase activity appears specifically in sporulating cells heterozygous for the mating-type locus (MAT). We identified a sporulation-specific glucoamylase gene (SGA) and show that expression of SGA is positively regulated by the mating-type genes, both MATa1 and MAT alpha 2. Northern blot analysis revealed that control of SGA is exerted at the level of RNA production. Expression of SGA or the consequent degradation of glycogen to glucose in cells is not required for meiosis or sporulation, since MATa/MAT alpha diploid cells homozygous for an insertion mutation at SGA still formed four viable ascospores.

scholarly journals Epigenetic switching of transcriptional states: cis- and trans-acting factors affecting establishment of silencing at the HMR locus in Saccharomyces cerevisiae.

1993 ◽  
Vol 13 (7) ◽  
pp. 3919-3928 ◽  
Author(s):  
L Sussel ◽  
D Vannier ◽  
D Shore
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Gene Dosage ◽  
Autonomously Replicating Sequence ◽  
Type Locus ◽  
Factors Affecting ◽  
Mating Type Locus ◽  
Colony Color ◽  
Diploid Cells ◽  
Cis And Trans

In this study, we used the ADE2 gene in a colony color assay to monitor transcription from the normally silent HMR mating-type locus in Saccharomyces cerevisiae. This sensitive assay reveals that some previously identified cis- and trans-acting mutations destabilize silencing, causing genetically identical cells to switch between repressed and derepressed transcriptional states. Deletion of the autonomously replicating sequence (ARS) consensus element at the HMR-E silencer or mutation of the silencer binding protein RAP1 (rap1s) results in the presence of large sectors within individual colonies of both repressed (Ade-, pink) and derepressed (Ade+, white) cells. These results suggest that both the ARS consensus element and the RAP1 protein play a role in the establishment of repression at HMR. In diploid cells, the two copies of HMR appear to behave identically, suggesting that the switching event, though apparently stochastic, reflects some property of the cell rather than a specific event at each HMR locus. In the ADE2 assay system, silencing depends completely upon the function of the SIR genes, known trans-acting regulators of the silent loci, and is sensitive to the gene dosage of two SIR genes, SIR1 and SIR4. Using the ADE2 colony color assay in a genetic screen for suppressors of rap1s, silencer ARS element deletion double mutants, we have identified a large number of genes that may affect the establishment of repression at the HMR silent mating-type locus.

scholarly journals THE ACTION OF HOMOTHALLISM GENES IN SACCHAROMYCES DIPLOIDS DURING VEGETATIVE GROWTH AND THE EQUIVALENCE OF hm  a and HMα LOCI FUNCTIONS

Genetics ◽  
1977 ◽  
Vol 85 (3) ◽  
pp. 407-416
Author(s):  
Amar J S Klar ◽  
Seymour Fogel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Spore Germination ◽  
Vegetative Growth ◽  
Mitotic Division ◽  
Type Locus ◽  
Growth Cycles ◽  
Mating Type Locus ◽  
Diploid Cells ◽  
Genotype A

ABSTRACT The action of homothallism genes in vegetatively growing diploid cells was examined. The results demonstrate that homothallism genes function during regular vegetative growth cycles as well as during the first few divisions after spore germination. A procedure based on ultraviolet-induced reciprocal mitotic recombination monitored by homozygosity for cryptopleurine resistance (a recessive marker closely linked to the mating-type locus) allowed us to identify and recover Saccharomyces cerevisiae colonies sectored for the mating-type locus i.e., a/a and α/α. Homothallism genes can switch a/a or α/α vegetative diploid cells, generated from a strain with genotype a/α HO/ho HMα/HMα HM  a/HM  a, to a/α diploids or a/a/α/α tetraploids during a given mitotic division cycle. We found that both a/a and α/α sectors generated from a strain with genotype a/α HO/HO hmα/hmα hm  a/HM  a switch to a/α diploids or a/a/α/α tetraploids. This finding supports Naumov and Tolstorukov's suggestion (1973) that the hm  a allele provides for the same functions as the HMα allele, namely, a switch at the mating-type locus from α to a. The HO allele is dominant to ho but hm  a and HM  a alleles are codominant. A loose linkage between the mating-type and the HMα loci (∼55cM), confirming Harashima, Nogi and Oshima (1974) data, was observed.

Epigenetic switching of transcriptional states: cis- and trans-acting factors affecting establishment of silencing at the HMR locus in Saccharomyces cerevisiae

1993 ◽  
Vol 13 (7) ◽  
pp. 3919-3928
Author(s):  
L Sussel ◽  
D Vannier ◽  
D Shore
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Gene Dosage ◽  
Autonomously Replicating Sequence ◽  
Type Locus ◽  
Factors Affecting ◽  
Mating Type Locus ◽  
Colony Color ◽  
Diploid Cells ◽  
Cis And Trans

In this study, we used the ADE2 gene in a colony color assay to monitor transcription from the normally silent HMR mating-type locus in Saccharomyces cerevisiae. This sensitive assay reveals that some previously identified cis- and trans-acting mutations destabilize silencing, causing genetically identical cells to switch between repressed and derepressed transcriptional states. Deletion of the autonomously replicating sequence (ARS) consensus element at the HMR-E silencer or mutation of the silencer binding protein RAP1 (rap1s) results in the presence of large sectors within individual colonies of both repressed (Ade-, pink) and derepressed (Ade+, white) cells. These results suggest that both the ARS consensus element and the RAP1 protein play a role in the establishment of repression at HMR. In diploid cells, the two copies of HMR appear to behave identically, suggesting that the switching event, though apparently stochastic, reflects some property of the cell rather than a specific event at each HMR locus. In the ADE2 assay system, silencing depends completely upon the function of the SIR genes, known trans-acting regulators of the silent loci, and is sensitive to the gene dosage of two SIR genes, SIR1 and SIR4. Using the ADE2 colony color assay in a genetic screen for suppressors of rap1s, silencer ARS element deletion double mutants, we have identified a large number of genes that may affect the establishment of repression at the HMR silent mating-type locus.

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 Mating Type in Chlamydomonas Is Specified by mid, the Minus-Dominance Gene

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 859-869 ◽  
Author(s):  
Patrick J Ferris ◽  
Ursula W Goodenough
Keyword(s):  
Transcription Factor ◽  
Mating Type ◽  
Codon Bias ◽  
Leucine Zipper ◽  
Laboratory Strain ◽  
Leucine Zipper Motif ◽  
Type Locus ◽  
Diploid Cells ◽  
Necessary And Sufficient

Diploid cells of Chlamydomonas reinhardtii that are heterozygous at the mating-type locus (mt  +/mt  –) differentiate as minus gametes, a phenomenon known as minus dominance. We report the cloning and characterization of a gene that is necessary and sufficient to exert this minus dominance over the plus differentiation program. The gene, called mid, is located in the rearranged (R) domain of the mt  – locus, and has duplicated and transposed to an autosome in a laboratory strain. The imp11 mt  – mutant, which differentiates as a fusion-incompetent plus gamete, carries a point mutation in mid. Like the fus1 gene in the mt  + locus, mid displays low codon bias compared with other nuclear genes. The mid sequence carries a putative leucine zipper motif, suggesting that it functions as a transcription factor to switch on the minus program and switch off the plus program of gametic differentiation. This is the first sex-determination gene to be characterized in a green organism.

scholarly journals INCREASED SPONTANEOUS MITOTIC SEGREGATION IN MMS-SENSITIVE MUTANTS OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1977 ◽  
Vol 87 (2) ◽  
pp. 229-236
Author(s):  
Satya Prakash ◽  
Louise Prakash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Methyl Methanesulfonate ◽  
X Rays ◽  
X Ray ◽  
Complementation Groups

ABSTRACT Methyl methanesulfonate (MMS)-sensitive mutants of Saccharomyces cerevisiae belonging to four different complementation groups, when homozygous, increase the rate of spontaneous mitotic segregation to canavanine resistance from heterozygous sensitive (canr/+) diploids by 13- to 170-fold. The mms8—1 mutant is MMS and X-ray sensitive and increases the rate of spontaneous mitotic segregation 170-fold. The mms9—1 and mms13—1 mutants are sensitive to X rays and UV, respectively, in addition to MMS, and increase the rate of spontaneous mitotic segregation by 13-fold and 85-fold, respectively. The mutant mms21—1 is sensitive to MMS, X rays and UV and increases the rate of spontaneous mitotic segregation 23-fold.

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