Two tightly linked silent cassettes in the mating-type region of Schizosaccharomyces pombe

1984 ◽  
Vol 8 (3) ◽  
pp. 199-203 ◽  
Author(s):  
Richard Egel
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mating Type ◽  
Type Region

scholarly journals MATING-TYPE MUTATIONS IN SCHIZOSACCHAROMYCES POMBE: ISOLATION OF MUTANTS AND ANALYSIS OF STRAINS WITH AN h  - or h  + PHENOTYPE

Genetics ◽  
1976 ◽  
Vol 83 (2) ◽  
pp. 259-273
Author(s):  
James H Meade ◽  
Herbert Gutz
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Gene Product ◽  
Mating Type ◽  
Sexual Cycle ◽  
Type Region ◽  
Type Allele ◽  
Mating Type Gene ◽  
Auxiliary Gene ◽  
Type Gene

ABSTRACT Mutants defective in various steps of the sexual cycle have been isolated from homothallic strains of Schizosaccharomyces pombe by Bresch, Müller and Egel (1968). These mutants include heterothallic h  + and h  - strains. We have isolated additional h  + and h  -mutants from homothallic strains. Those mutants which are due to mutations in the mating-type region were analyzed in detail. Our results show that the mating-type gene mat2 not only has a function in copulation and meiosis, but that it also regulates the formation of the map1 gene product (map1 is a mating-type auxiliary gene). Some of the h  - mutants have lost only one of the three functions while others are defective in at least two, and perhaps all three, functions. Further, we show that the mat1  - allele of h90 strains can mutate to mat1  + but that mutations in mat2 appear to affect the mutational behavior of mat1. Finally, we describe a new inactive mating-type allele, mat2*, which is different from mat2  0 in that it can mutate to mat2  +.

scholarly journals The mutator gene swi8 effects specific mutations in the mating-type region of Schizosaccharomyces pombe.

Genetics ◽  
1994 ◽  
Vol 138 (3) ◽  
pp. 621-632
Author(s):  
O Fleck ◽  
C Rudolph ◽  
A Albrecht ◽  
A Lorentz ◽  
P Schär ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Gene Conversion ◽  
Mating Type ◽  
Type Region ◽  
Mutator Phenotype ◽  
Mutator Gene ◽  
Hybrid Dna

Abstract The swi8+ gene of Schizosaccharomyces pombe appears to be involved in the termination step of copy synthesis during mating-type (MT) switching. Mutations in swi8 confer a general mutator phenotype and, in particular, generate specific mutations in the MT region. Sequencing of the MT cassettes of the h90 swi8-137 mutant revealed three altered sites. One is situated at the switching (smt) signal adjacent to the H1 homology box of the expression locus mat1:1. It reduces the rate of MT switching. The alteration at the smt signal arose frequently in other h90 swi8 strains and is probably caused by gene conversion in which the sequence adjacent to the H1 box of mat2:2 is used as template. This change might be generated during the process of MT switching when hybrid DNA formation is anomalously extended into the more heterologous region flanking the H1 homology box. In addition to the gene conversion at mat1:1, two mutations were found in the H3 homology boxes of the silent cassettes mat2:2 and mat3:3.

A mutated swi4 gene causes duplications in the mating-type region of Schizosaccharomyces pombe

1990 ◽  
Vol 18 (6) ◽  
pp. 501-509 ◽  
Author(s):  
Oliver Fleck ◽  
Lutz Heim ◽  
Herbert Gutz
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mating Type ◽  
Type Region

scholarly journals Localization and Properties of a Silencing Element Near the mat3-M Mating-Type Cassette of Schizosaccharomyces pombe

Genetics ◽  
1999 ◽  
Vol 151 (3) ◽  
pp. 945-963 ◽  
Author(s):  
Geneviève Thon ◽  
K Pernilla Bjerling ◽  
Inga Sig Nielsen
Keyword(s):  
Gene Expression ◽  
Schizosaccharomyces Pombe ◽  
Mating Type ◽  
Type Region ◽  
Double Deletion ◽  
Distal Side ◽  
Mating Type Genes ◽  
Promoter Specificity ◽  
Chromosome Ii ◽  
Affect Gene Expression

Abstract Transcription is repressed in a segment of Schizosaccharomyces pombe chromosome II that encompasses the mat2-P and mat3-M mating-type cassettes. Chromosomal deletion analysis revealed the presence of a repressor element within 500 bp of mat3-M. This element acted in synergy with the trans-acting factors Swi6, Clr1, Clr2, Clr3, and Clr4 and had several properties characteristic of silencers: it did not display promoter specificity, being able to silence not only the M mating-type genes but also the S. pombe ura4 and ade6 genes placed on the centromere-distal side of the mat3-M cassette; it could repress a gene when placed further than 2.6 kb from the promoter and it acted in both orientations, although with different efficiencies, the natural orientation repressing more stringently than the reverse. Following deletion of this element, two semistable states of expression of the mat3-M region were observed and these two states could interconvert. The deletion did not affect gene expression in the vicinity of the mat2-P cassette, 11 kb away from mat3-M. Conversely, deleting 1.5 kb on the centromere-proximal side of the mat2-P cassette, which was previously shown to partially derepress transcription around mat2-P, had no effect on gene expression near mat3-M. A double deletion removing the mat2-P and mat3-M repressor elements had the same effect as the single deletions on their respective cassettes when assayed in cells of the M mating type. These observations allow us to refine a model proposing that redundant pathways silence the mating type region of S. pombe.

scholarly journals INFLUENCE OF THE mat1-M ALLELE ON MEIOTIC RECOMBINATION IN THE MATING-TYPE REGION OF SCHIZOSACCHAROMYCES POMBE

Genetics ◽  
1978 ◽  
Vol 88 (2) ◽  
pp. 235-238
Author(s):  
James H Meade ◽  
Herbert Gutz
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mating Type ◽  
Meiotic Recombination ◽  
Mitotic Recombination ◽  
Type Region

ABSTRACT Angehrn and Gutz (1968) have shown that homozygosity for the mat1-M allele in diploid strains of Schizosaccharomyces pombe increases mitotic recombination between his7 and mat2. In this paper, we report that meiotic recombination frequencies can vary from 3.4 to 16.1 percent between his7 and his2 and that this variation is due to the combination of alleles at the mat1 and mat2 loci.

Four Chromo-domain Proteins of Schizosaccharomyces pombe Differentially Repress Transcription at Various Chromosomal Locations

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 551-568 ◽  
Author(s):  
Geneviève Thon ◽  
Janne Verhein-Hansen
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mating Type ◽  
Transcriptional Repression ◽  
Transcriptional Silencing ◽  
Yeast Genome ◽  
Chromosome Stability ◽  
Yeast Saccharomyces Cerevisiae ◽  
Position Effects ◽  
Type Region ◽  
Chromo Domain

Abstract Transcription is repressed in regions of the fission yeast genome close to centromeres, telomeres, or the silent mating-type cassettes mat2-P and mat3-M. The repression involves the chromo-domain proteins Swi6 and Clr4. We report that two other chromo-domain proteins, Chp1 and Chp2, are also important for these position effects. Chp1 showed a specificity for centromeric regions. Its essentiality for the transcriptional repression of centromeric markers correlates with its importance for chromosome stability. Chp2 appeared more pleiotropic. Its effects on centromeric silencing were less pronounced than those of Chp1, and it participated in telomeric position effects and transcriptional silencing in the mating-type region. We also found that PolII-transcribed genes were repressed when placed in one of the Schizosaccharomyces pombe rDNA clusters, a situation analogous to that in the budding yeast Saccharomyces cerevisiae. Chp2, Swi6, Clr4, and, to a lesser extent, Chp1 participated in that repression.

The mating-type region of Schizosaccharomyces pombe contains an essential gene encoding a protein homologous to human modulators of HIV transactivation

Gene ◽  
1994 ◽  
Vol 145 (2) ◽  
pp. 205-210 ◽  
Author(s):  
Holger Michae ◽  
Henning Schmidt ◽  
Oliver Fleck ◽  
Herbert Gutz ◽  
Christian Liedtke ◽  
...  
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mating Type ◽  
Essential Gene ◽  
Gene Encoding ◽  
Type Region

scholarly journals Three additional linkage groups that repress transcription and meiotic recombination in the mating-type region of Schizosaccharomyces pombe.

Genetics ◽  
1994 ◽  
Vol 138 (1) ◽  
pp. 29-38 ◽  
Author(s):  
G Thon ◽  
A Cohen ◽  
A J Klar
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Mating Type ◽  
Meiotic Recombination ◽  
Chromosomal Region ◽  
Linkage Groups ◽  
Type Region ◽  
Cis Acting ◽  
In Trans ◽  
Mating Type Genes

Abstract The mating-type genes of Schizosaccharomyces pombe are found at three locations in the same chromosomal region. These genes are in an active configuration at the mat1 locus and in an inactive configuration at the mat2 and mat3 loci. The mechanism that represses transcription of mat2 and mat3 also inactivates other promoters introduced nearby and is accompanied by a block to meiotic recombination in the mat2-mat3 interval, suggesting that this mechanism involves a particular chromatin structure. We present evidence that the transcription and recombination blocks require three newly defined trans-acting loci, clr2, clr3 and clr4, in addition to the previously identified clr1, rik1 and swi6 loci. We also investigated the role of mat2 cis-acting sequences in silencing. Four cis-acting elements that repress mat2 in a plasmid context were previously identified. Deletion of two of these elements proved to have little effect in a chromosomal context. However, when combined with mutations in trans-acting genes, deletion of the same two elements greatly enhanced mat2 expression. The observed cumulative effects suggest a redundancy in the silencing mechanism.

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