scholarly journals Deoxyribonucleotide biosynthesis in yeast (Saccharomyces cerevisiae). A ribonucleotide reductase system of sufficient activity for DNA synthesis

1984 ◽  
Vol 140 (2) ◽  
pp. 281-287 ◽  
Author(s):  
Manfred LAMMERS ◽  
Hartmut FOLLMANN
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Ribonucleotide Reductase ◽  
Yeast Saccharomyces Cerevisiae

On the mechanism of premeiotic DNA synthesis in the yeast Saccharomyces cerevisiae

1982 ◽  
Vol 141 (1) ◽  
pp. 53-62 ◽  
Author(s):  
Leland H. Johnston ◽  
Donald H. Williamson ◽  
Anthony L. Johnson ◽  
Daphne J. Fennell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Yeast Saccharomyces Cerevisiae

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 Interaction of replication factor Sld3 and histone acetyl transferase Esa1 alleviates gene silencing and promotes the activation of late and dormant replication origins

Genetics ◽  
2020 ◽  
Vol 217 (1) ◽  
pp. 1-11
Author(s):  
Seiji Tanaka
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Silencing ◽  
Dna Synthesis ◽  
Histone Acetyltransferase ◽  
Replication Origins ◽  
Histone Acetyl Transferase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Step Process ◽  
Helicase Loading ◽  
Rate Limiting

Abstract DNA replication in eukaryotes is a multi-step process that consists of three main reactions: helicase loading (licensing), helicase activation (firing), and nascent DNA synthesis (elongation). Although the contributions of some chromatin regulatory factors in the licensing and elongation reaction have been determined, their functions in the firing reaction remain elusive. In the budding yeast Saccharomyces cerevisiae, Sld3, Sld7, and Cdc45 (3–7–45) are rate-limiting in the firing reaction and simultaneous overexpression of 3–7–45 causes untimely activation of late and dormant replication origins. Here, we found that 3–7–45 overexpression not only activated dormant origins in the silenced locus, HMLα, but also exerted an anti-silencing effect at this locus. For these, interaction between Sld3 and Esa1, a conserved histone acetyltransferase, was responsible. Moreover, the Sld3–Esa1 interaction was required for the untimely activation of late origins. These results reveal the Sld3–Esa1 interaction as a novel level of regulation in the firing reaction.

Relationships between sensitivity to hydroxyurea and 4-methyl-5-amino-1-formylisoquinoline thiosemicarbazone (MAIQ) and ribonucleotide reductase RNR2 mRNA levels in strains of Saccharomyces cerevisiae

1989 ◽  
Vol 67 (7) ◽  
pp. 352-357 ◽  
Author(s):  
Dawn A. H. Rittberg ◽  
Jim A. Wright
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ribonucleotide Reductase ◽  
Messenger Rna ◽  
Mammalian Cells ◽  
Antitumor Agents ◽  
Resistance Mechanisms ◽  
Small Subunit ◽  
Common Mechanism ◽  
Mrna Levels ◽  
Yeast Saccharomyces Cerevisiae

Ribonucleotide reductase is responsible for providing the deoxyribonucleotide precursors for DNA synthesis. In most species the enzyme consists of a large and a small subunit, both of which are required for activity. In mammalian cells, the small subunit is the site of action of several antitumor agents, including hydroxyurea and 4-methyl-5-amino-1-formylisoquinoline thiosemicarbazone (MAIQ). The mRNA levels for the small subunit of ribonucleotide reductase (RNR2) and sensitivity to hydroxyurea and MAIQ were determined in four strains of the yeast, Saccharomyces cerevisiae. Two strains exhibited significantly different sensitivities to both hydroxyurea and MAIQ, which closely correlated with differences in the levels of RNR2 mRNA. These results are consistent with recent observations with mammalian cells in culture, and indicate that a common mechanism of resistance to hydroxyurea and related drugs occurs through the elevation in ribonucleotide reductase message levels. A transplason mutagenized strain with marked structural modifications in RNR2 DNA and mRNA showed an extreme hypersensitivity to hydroxyurea but not to MAIQ, providing evidence that the two drugs do not inhibit the RNR2 subunit by the same mechanism. In addition, a yeast strain isolated for low but reproducible resistance to MAIQ exhibited a sensitivity to hydroxyurea similar to the parental wild-type strain, supporting the idea that the two drugs inhibit the activity of RNR2 by unique mechanisms. These yeast strains provide a useful approach for further studies into the regulation of eucaryotic ribonucleotide reduction and drug resistance mechanisms involving a key rate-limiting step in DNA synthesis.Key words: Saccharomyces cerevisiae, reductase, messenger RNA, hydroxyurea, thiosemicarbazone.

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 ANALYSIS OF MEIOSIS-DEFECTIVE MUTATIONS IN YEAST BY PHYSICAL MONITORING OF RECOMBINATION

Genetics ◽  
1986 ◽  
Vol 113 (3) ◽  
pp. 551-567
Author(s):  
Rhona H Borts ◽  
Michael Lichten ◽  
James E Haber
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Synthesis ◽  
Vegetative Growth ◽  
Growth Conditions ◽  
Intragenic Recombination ◽  
Dna Molecules ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Restriction Fragments ◽  
High Level

ABSTRACT We have developed a method by which the extent of physical exchange of DNA molecules can be determined throughout meiosis in the yeast Saccharomyces cerevisiae. We have used this technique to analyze the effect of five meiosis-defective mutations (rad6, rad50, rad52, rad57 and spo11) on the physical exchange of DNA molecules. In the same experiments, we have also measured other meiotic parameters, such as premeiotic DNA synthesis, commitment to intragenic recombination, haploidization, ascus formation, and viability. rad50 and spo11 diploids make an undetectable amount of physically recombined DNA and <1% of wild-type levels of viable intragenic recombinants. In contrast, diploids homozygous for rad52, rad6 or rad57 all yield significant amounts of novel restriction fragments which arise by recombination. rad57 diploids make nearly wild-type levels of the recombined restriction fragments, although they produce <10% of the wild-type levels of viable intragenic recombinants. rad52 strains are also capable of a significant (33%) amount of exchange of DNA molecules, but make <1% of wild-type levels of viable intragenic recombinants. rad6 diploids are also capable of undergoing a high level of exchange, as measured by the appearance of the recombined restriction fragment. In addition, rad6 diploids show an unusual allele- or locus-specific variability in the level of viable intragenic recombinants produced. Although rad6 diploids produce no viable spores, they are able to complete a significant amount of haploidization upon return to vegetative growth conditions.

Sign in / Sign up

Export Citation Format

Share Document