GCN5-Dependent Histone H3 Acetylation and RPD3-Dependent Histone H4 Deacetylation have Distinct, Opposing Effects on IME2 Transcription, during Meiosis and during Vegetative Growth, in Budding Yeast

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 96; no. 12; pp. 6835 - 6840
• Main Authors: Burgess, Sean M., Ajimura, Masahiro, Kleckner, Nancy
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 08.06.1999; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Acetates; Acetylation; Biological Sciences; Cell Cycle Proteins; Cells; DNA-Binding Proteins; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression Regulation, Fungal; Genes; Genetics; Histone Acetyltransferases; Histone Deacetylases; Histones; Histones - genetics; Histones - metabolism; Intracellular Signaling Peptides and Proteins; Meiosis; Meiosis - genetics; Mutation; Promoter regions; Protein Kinases - genetics; Protein Kinases - metabolism; Protein-Serine-Threonine Kinases; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins; Somatic cells; Spores; Sporulation; Transcription Factors - metabolism; Transcription, Genetic; Vegetative growth; Yeast
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.12.6835

Diploid yeast undergo meiosis under certain conditions of nutrient limitation, which trigger a transcriptional cascade involving two key regulatory genes. IME1 is a positive activator of IME2, which activates downstream genes. We report that Gcn5, a histone H3 acetylase, plays a central role in initiation of meiosis via effects on IME2 expression. An allcle, gcn5-21, was isolated as a mutant defective in spore formation. gcn5-21 fails to carry out meiotic DNA replication, recombination, or meiotic divisions. This mutant also fails to induce IME2 transcription; IME1 transcription, however, is essentially normal. Further investigation shows that during wild-type meiosis the IME2 promoter undergoes an increase in the level of bound acetylated histone H3. This increase is contemporaneous with meiotic induction of IME2 transcription and is absent in gcn5-21. In contrast, the RPD3 gene, which encodes a histone H4 deacetylase and is known to be required for repression of basal IME2 transcription in growing yeast cells, is not involved in induction of IME2 transcription or IME2 histone acetylation during meiosis. These and other results suggest that Gcn5 and Rpd3 play distinct roles, modulating transcription initiation in opposite directions under two different cellular conditions. These roles are implemented via opposing effects of the two gene products on acetylation of two different histones. Finally, we find that gcn5 and rpd3 single mutants are not defective in meiosis if acetate is absent and respiration is promoted by a metabolically unrelated carbon source. Perhaps intracellular acetate levels regulate meiosis by controlling histone acetylation patterns.