Project description:We found ribosomal transcription factor Ifh1p is dynamically acetylated and phosphorylated in response to nutrient cues. ChIP-seq data revealed dynamic binding to ribosomal genes (RP) during the OX growth phase of the yeast metabolic cycle (YMC) when RP genes are highly induced, and weaker binding in the RC quiescent-like phase. Besides RP genes, our ChIP-seq data also reveals binding of Ifh1p to non-RP genes such as translation factors and metabolic genes. Examination of Ifh1p binding over two timepoints of the YMC (OX, RC) using Input as the control.
Project description:We found acetyl-CoA levels increase when cells are committed to growth. We also found 3 components of the SAGA complex, Spt7p, Sgf73p and Ada3p as well as histones are dynamically acetylated in tune with the acetyl-CoA levels. ChIP-seq study reveals SAGA and H3K9ac predominantly occupy growth genes at the OX growth phase of the yeast metabolic cycle indicating acetyl-CoA levels may drive growth gene transcription program through acetylation of these proteins. Examination of H3K9ac and SAGA binding over two timepoints using H3 and Input as controls
Project description:We found acetyl-CoA levels increase when cells are committed to growth. We also found 3 components of the SAGA complex, Spt7p, Sgf73p and Ada3p as well as histones are dynamically acetylated in tune with the acetyl-CoA levels. ChIP-seq study reveals SAGA and H3K9ac predominantly occupy growth genes at the OX growth phase of the yeast metabolic cycle indicating acetyl-CoA levels may drive growth gene transcription program through acetylation of these proteins.
Project description:We found ribosomal transcription factor Ifh1p is dynamically acetylated and phosphorylated in response to nutrient cues. ChIP-seq data revealed dynamic binding to ribosomal genes (RP) during the OX growth phase of the yeast metabolic cycle (YMC) when RP genes are highly induced, and weaker binding in the RC quiescent-like phase. Besides RP genes, our ChIP-seq data also reveals binding of Ifh1p to non-RP genes such as translation factors and metabolic genes.
Project description:The SAGA co-activator complex contains distinct chromatin-modifying activities and is recruited by DNA-bound activators to regulate the expression of a subset of genes. Surprisingly, recent studies revealed little overlap between genome-wide SAGA-binding profiles and changes in gene expression upon depletion of subunits of the complex. As indicators of SAGA recruitment on chromatin, we monitored in yeast and human cells the genome-wide distribution of histone H3K9 acetylation and H2B ubiquitination, which are respectively deposited or removed by SAGA. Changes in these modifications after inactivation of the corresponding enzyme revealed that SAGA acetylates the promoters and deubiquitinates the transcribed region of all expressed genes. In agreement with this broad distribution, we show that SAGA plays a critical role for RNA polymerase II recruitment at all expressed genes. In addition, through quantification of newly synthesized RNA, we demonstrated that SAGA inactivation induced a strong decrease of mRNA synthesis at all tested genes. Analysis of the SAGA deubiquitination activity further revealed that SAGA acts on the whole transcribed genome in a very fast manner indicating a highly dynamic association of the complex with chromatin. Thus, our study uncovers a new function for SAGA as a bone fide co-factor for all RNA Polymerase II transcription. Comparison of H3K9ac, H2Bub and RNA Pol II distributions in WT yeast cells and upon the loss of SAGA activities.
Project description:Occupancy profiling of H3K9ac in fission yeast Schizosaccharomyces pombe Agilent 60mer array was used to analyze DNA recovered by immunoprecipitation of H3k9ac from asynchronous culture of fission yeast.
Project description:A defining characteristic of quiescent cells is their low level of gene activity compared to growing cells. Using a yeast model for cellular quiescence, we compared the genome-wide profiles of multiple histone modifications between growing and quiescent cells, and correlated these profiles with the presence of RNA polymerase II and its transcripts. Quiescent cells retained several forms of histone methylation normally associated with transcriptionally active chromatin and had many transcripts in common with growing cells. Quiescent cells also contained high levels of RNA polymerase II, but only low levels of the canonical initiating and elongating forms of the polymerase. The data suggest that the transcript and histone methylation marks in quiescent cells were either inherited from growing cells or established early during the development of quiescence and then retained in this non-growing cell population. This might ensure that quiescent cells can rapidly adapt to a changing environment to resume growth. RNA-seq analysis was performed in yeast Log-phase cells and purified Quiescent yeast cells and the transcriptomes in each were compared. The RNA data was correlated with genomic RNA polymerase II and histone H3 methylation occupancy profiles in the log and quiescent cells.
Project description:The SAGA co-activator complex contains distinct chromatin-modifying activities and is recruited by DNA-bound activators to regulate the expression of a subset of genes. Surprisingly, recent studies revealed little overlap between genome-wide SAGA-binding profiles and changes in gene expression upon depletion of subunits of the complex. As indicators of SAGA recruitment on chromatin, we monitored in yeast and human cells the genome-wide distribution of histone H3K9 acetylation and H2B ubiquitination, which are respectively deposited or removed by SAGA. Changes in these modifications after inactivation of the corresponding enzyme revealed that SAGA acetylates the promoters and deubiquitinates the transcribed region of all expressed genes. In agreement with this broad distribution, we show that SAGA plays a critical role for RNA polymerase II recruitment at all expressed genes. In addition, through quantification of newly synthesized RNA, we demonstrated that SAGA inactivation induced a strong decrease of mRNA synthesis at all tested genes. Analysis of the SAGA deubiquitination activity further revealed that SAGA acts on the whole transcribed genome in a very fast manner indicating a highly dynamic association of the complex with chromatin. Thus, our study uncovers a new function for SAGA as a bone fide co-factor for all RNA Polymerase II transcription. Comparison of H3K9ac and H2Bub distributions in control HeLa cells and upon the inactivation of SAGA enzymatic activities
