Project description:Signal intensity data for rpd3 delete, H3delta(1-28), H3(K4,9,14,18,23,27Q), H4delta(2-26), H4(K5,8,12,16Q), rpd3 delete H3delta(1-28), and rpd3 delete H4(K5,8,12,16Q) yeast grown in rich (YPD) media
Project description:We have performed a comprehensive analysis of the involvement of histone H3 and H4 residues in the regulation of chronological lifespan in yeast. Residues where substitution resulted in the most pronounced lifespan extension are all on the exposed face of the nucleosome, with the exception of H3E50, which is present on the lateral surface, between two DNA gyres. Other residues that had a more modest effect on lifespan extension were concentrated at the extremities of the H3-H4 dimer, suggesting a role in stabilizing the dimer in its nucleosome frame. Residues implicated in a reduced lifespan were buried in the histone handshake motif, suggesting that these mutations destabilize the octamer structure. All residues exposed on the disk and that caused lifespan extension are known to interact with Sir3. We find that substitution of H4K16 and H4H18 cause Sir3 to redistribute from telomeres and silent mating loci to secondary positions, often enriched for Rap1 or Abf1 binding sites, whereas H3E50 does not. The redistributed Sir3 cause transcriptional repression at most of the new loci, including of genes where null mutants were previously shown to extend chronological lifespan. The transcriptomic profiles of H4K16 and H4H18 mutant strains are very similar, and compatible with a DNA replication stress response. This is distinct from the transcriptomic profile of H3E50, which matches strong induction of oxidative phosphorylation. We propose that different clusters of H3 and H4 residues are involved in either binding to non-histone proteins, or in destabilizing the association of the nucleosome DNA, or disrupting binding of a H3-H4 dimer in the nucleosome, or disturbing the structural stability of the octamer, each category impacting on chronological lifespan through a different path.
Project description:We have performed a comprehensive analysis of the involvement of histone H3 and H4 residues in the regulation of chronological lifespan in yeast. Residues where substitution resulted in the most pronounced lifespan extension are all on the exposed face of the nucleosome, with the exception of H3E50, which is present on the lateral surface, between two DNA gyres. Other residues that had a more modest effect on lifespan extension were concentrated at the extremities of the H3-H4 dimer, suggesting a role in stabilizing the dimer in its nucleosome frame. Residues implicated in a reduced lifespan were buried in the histone handshake motif, suggesting that these mutations destabilize the octamer structure. All residues exposed on the disk and that caused lifespan extension are known to interact with Sir3. We find that substitution of H4K16 and H4H18 cause Sir3 to redistribute from telomeres and silent mating loci to secondary positions, often enriched for Rap1 or Abf1 binding sites, whereas H3E50 does not. The redistributed Sir3 cause transcriptional repression at most of the new loci, including of genes where null mutants were previously shown to extend chronological lifespan. The transcriptomic profiles of H4K16 and H4H18 mutant strains are very similar, and compatible with a DNA replication stress response. This is distinct from the transcriptomic profile of H3E50, which matches strong induction of oxidative phosphorylation. We propose that different clusters of H3 and H4 residues are involved in either binding to non-histone proteins, or in destabilizing the association of the nucleosome DNA, or disrupting binding of a H3-H4 dimer in the nucleosome, or disturbing the structural stability of the octamer, each category impacting on chronological lifespan through a different path.
Project description:The Mediator complex transmits activation signals from DNA bound transcription factors to the core transcription machinery. Genome wide localization studies have demonstrated that Mediator occupancy not only correlates with high levels of transcription, but that the complex also is present at transcriptionally silenced locations. We provide evidence that Mediator localization is guided by an interaction with histone tails, and that this interaction is regulated by their post-translational modifications. A quantitative, high-density genetic interaction map revealed links between Mediator components and factors affecting chromatin structure, especially histone deacetylases. Peptide binding assays demonstrated that pure wild type Mediator forms stable complexes with the tails of Histone H3 and H4. These binding assays also showed Mediator – histone H4 peptide interactions are specifically inhibited by acetylation of the histone H4 lysine 16, a residue critical in transcriptional silencing. Finally, these findings were validated by tiling array analysis, that revealed a broad correlation between Mediator and nucleosome occupancy in vivo, but a negative correlation between Mediator and nucleosomes acetylated at histone H4 lysine 16. Our studies show that chromatin structure and the acetylation state of histones are intimately connected to Mediator localization.
Project description:The Mediator complex transmits activation signals from DNA bound transcription factors to the core transcription machinery. Genome wide localization studies have demonstrated that Mediator occupancy not only correlates with high levels of transcription, but that the complex also is present at transcriptionally silenced locations. We provide evidence that Mediator localization is guided by an interaction with histone tails, and that this interaction is regulated by their post-translational modifications. A quantitative, high-density genetic interaction map revealed links between Mediator components and factors affecting chromatin structure, especially histone deacetylases. Peptide binding assays demonstrated that pure wild type Mediator forms stable complexes with the tails of Histone H3 and H4. These binding assays also showed Mediator – histone H4 peptide interactions are specifically inhibited by acetylation of the histone H4 lysine 16, a residue critical in transcriptional silencing. Finally, these findings were validated by tiling array analysis, that revealed a broad correlation between Mediator and nucleosome occupancy in vivo, but a negative correlation between Mediator and nucleosomes acetylated at histone H4 lysine 16. Our studies show that chromatin structure and the acetylation state of histones are intimately connected to Mediator localization. Med8-TAP strain ChIPed with IgG beads vs. Input in Saccharomyces cerevisiae
Project description:We have performed a comprehensive analysis of the involvement of histone H3 and H4 residues in the regulation of chronological lifespan in yeast. Residues where substitution resulted in the most pronounced lifespan extension are all on the exposed face of the nucleosome, with the exception of H3E50, which is present on the lateral surface, between two DNA gyres. Other residues that had a more modest effect on lifespan extension were concentrated at the extremities of the H3-H4 dimer, suggesting a role in stabilizing the dimer in its nucleosome frame. Residues implicated in a reduced lifespan were buried in the histone handshake motif, suggesting that these mutations destabilize the octamer structure. All residues exposed on the disk and that caused lifespan extension are known to interact with Sir3. We find that substitution of H4K16 and H4H18 cause Sir3 to redistribute from telomeres and silent mating loci to secondary positions, often enriched for Rap1 or Abf1 binding sites, whereas H3E50 does not. The redistributed Sir3 cause transcriptional repression at most of the new loci, including of genes where null mutants were previously shown to extend chronological lifespan. The transcriptomic profiles of H4K16 and H4H18 mutant strains are very similar, and compatible with a DNA replication stress response. This is distinct from the transcriptomic profile of H3E50, which matches strong induction of oxidative phosphorylation. We propose that different clusters of H3 and H4 residues are involved in either binding to non-histone proteins, or in destabilizing the association of the nucleosome DNA, or disrupting binding of a H3-H4 dimer in the nucleosome, or disturbing the structural stability of the octamer, each category impacting on chronological lifespan through a different path.
Project description:Characterization of H3 density, H3 or H4 acetylation, Rpd3 binding, TFIIB binding, and Rpb3 (pol II) binding in wild type and rpd3 cells as they transition from logarithmic growth to diauxic shift to quiescence [ChIP-Seq]
Project description:We have performed a comprehensive analysis of the involvement of histone H3 and H4 residues in the regulation of chronological lifespan in yeast. Residues where substitution resulted in the most pronounced lifespan extension are all on the exposed face of the nucleosome, with the exception of H3E50, which is present on the lateral surface, between two DNA gyres. Other residues that had a more modest effect on lifespan extension were concentrated at the extremities of the H3-H4 dimer, suggesting a role in stabilizing the dimer in its nucleosome frame. Residues implicated in a reduced lifespan were buried in the histone handshake motif, suggesting that these mutations destabilize the octamer structure. All residues exposed on the disk and that caused lifespan extension are known to interact with Sir3. We find that substitution of H4K16 and H4H18 cause Sir3 to redistribute from telomeres and silent mating loci to secondary positions, often enriched for Rap1 or Abf1 binding sites, whereas H3E50 does not. The redistributed Sir3 cause transcriptional repression at most of the new loci, including of genes where null mutants were previously shown to extend chronological lifespan. The transcriptomic profiles of H4K16 and H4H18 mutant strains are very similar, and compatible with a DNA replication stress response. This is distinct from the transcriptomic profile of H3E50, which matches strong induction of oxidative phosphorylation. We propose that different clusters of H3 and H4 residues are involved in either binding to non-histone proteins, or in destabilizing the association of the nucleosome DNA, or disrupting binding of a H3-H4 dimer in the nucleosome, or disturbing the structural stability of the octamer, each category impacting on chronological lifespan through a different path.