Developmental regulation of a sporulation-specific enzyme activity in Saccharomyces cerevisiae.

During Saccharomyces cerevisiae sporulation distinct changes in translatable mRNA species have been detected by two-dimensional gel electrophoresis of the polypeptides produced in a messenger-dependent, cell-free rabbit reticulocyte lysate primed with RNA prepared from a/a, a/a, and a/a isogenic diploids at different stages of sporulation. The availability of functional mRNA increased by about 25% during the first 4 h after transfer of either sporulating (a/a.), or nonsporulating (a/a and a/a) diploids to sporulation medium. Thereafter functional mRNA decreased such that in the a/a strain after 24 h there was only about 50% of the amount in vegetative cells; a less marked decrease was observed in the a/a and a/a strains. Of 750 mRNA species detected, 43 underwent alterations only during sporulation in the a/a strain, whereas 36 changes were common to all three strains and one mRNA specific to a/a vegetative cells was detected. Only four of the sporulation-specific changes were due to the de novo appearance of translatable species, and two of these became predominant species of the total population. The majority of the specific changes were due to either permanent or transient increases in the concentration of individual mRNA species; 11 decreases were found. Changes were found at most stages of sporulation, although many occurred in either of two stages, one early (before 2 h) and the other later (between 6 and 8 h) when commitment to meiotic segregation was beginning. The results provide evidence for both quantitative and, to a lesser extent, qualitative transcriptional control of gene expression during sporulation.Sporulation in the yeast Saccharomyces cerevisiae is a useful system for studying development for several reasons: the genetics of S. cerei'isiae has been extensively studied, and many mutants with known physiological and biochemical characteristics are available; sporulation is readily initiated, and relatively synchronous populations of cells in various stages of sporulation can be obtained; only heterozygous MATa/MATa diploid cells can complete ascus formation under sporulation conditions, the haploid and homozygous diploids being unable to sporulate; and under the nitrogen starvation conditions utilized for the induction of synchronous sporulation, mitotic cell division does not occur, even in cells that do not sporulate. Therefore, this development process is not complicated by concomitant cell cycle events. This also allows one to establish which events during this regimen are due solely to step-down by looking at the behavior of nonsporulating strains.To understand how gene expression is regulated during development, it is first necessary to identify biochemical changes specifically associated with the process. Genetic analyses have implicated at least 50 loci to code for functions indispensible to the process of meiosis and sporulation (16), and it has been established that sporulation in S. cerevisiae is dependent upon certain vegetative gene products (29,30). However, only a very few bioche...

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Developmental changes in translatable RNA species associated with meiosis and spore formation in Saccharomyces cerevisiae.

Weir-Thompson¹,

Dawes²

1984

“…Three unlinked homologous genes, STA1, STA2, and STA3, encode the secreted glucoamylase isozymes I, II, and III (33). These genes are absent in S. cerevisiae, but a related gene, SGA (37) or SAG (5), which encodes an intracellular, sporulation-specific glucoamylase, is present. S. cerevisiae and the variant diastaticus mate readily and produce viable spores (36).…”

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confidence: 99%

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

Dranginis¹

1989

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 STA) regulation but that deletion of MATal 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 MA Tal and a product of the MATa 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 sporulationspecific glucoamylase of S. cerevisiae. A diploid strain with a MATal deletion showed normal induction of STAl in sporulation medium, but SGA expression was abolished. Therefore, these two homologous and closely linked glucoamylase genes are induced by different mechanisms during sporulation. STAl 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.Saccharomyces cerevisiae var. diastaticus is a variant strain of yeast characterized by the ability to secrete glucoamylase, an enzyme that catalyzes the digestion of starch.

“…On the other hand, it has been showh that protein synthesis is essential for sporulation (13,15), and genetic studies suggest that approximately 50 genes are uniquely required for sporulation (6). More recently, several protein modifications specific to sporulation have been observed (27), and one sporulationspecific enzyme, an a-glucosidase involved in glycogen catabolism, has been described (4).…”

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confidence: 99%

“…It seemed possible that the failure to detect sporulationspecific proteins by a two-dimensional polyacrylamide gel electrophoretic analysis was due to the limited sensitivity of this technique; only the most abundant 400 of approximately 4,000 different proteins (10) screened a yeast DNA library for genes expressed preferentially in MATa/MATot cells during sporulation. In this communication we report the identification of 14 sporulationspecific genes.…”

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confidence: 99%

Isolation of DNA sequences preferentially expressed during sporulation in Saccharomyces cerevisiae.

Percival‐Smith¹,

Segall²

1984

103

106

A differential hybridization screen has been used to identify genes cloned from the yeast Saccharomyces cerevisiae that are expressed preferentially during sporulation. Duplicate copies of a partial Sau3A yeast DNA library prepared in the vector pBR322 were hybridized with radioactive cDNA probes representing the mRNA populations of sporulating aa cells and asporogenous aao cells at various times after transfer to sporulation medium. Thirty-eight clones showed an enhanced hybridization signal with the aa sporulation probe relative to the aa control cDNA probe. A comparison of the array of fragments produced by restriction endonuclease digestion of these plasmids suggested that 15 different sequences had been cloned. An RNA blot analysis using these cloned DNAs to probe RNAs purified from aa, aa, and aa cells harvested either during vegetative growth or at 10 h after transfer to sporulation medium indicated that 14 different sporulation-specific genes had been identified.