Histone variants specific to the transcriptionally active, amitotically dividing macronucleus of the unicellular eucaryote, tetrahymena thermophila

Allis, C. David; Glover, Claiborne V.C.; Bowen, Josephine; Gorovsky, Martin A.

doi:10.1016/0092-8674(80)90307-4

Cited by 201 publications

(127 citation statements)

References 28 publications

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“…1D, ␣-H3): 0 (unacetylated H3) to 5 (species of H3 with five acetylations). These rungs are acetylation-dependent because phosphatase treatment does not disrupt resolution of this H3 ladder (data not shown), and previous analyses show that MAC H3 has no detectable phosphorylation (37,38).…”

Section: Resultsmentioning

confidence: 88%

Long-distance combinatorial linkage between methylation and acetylation on histone H3 N termini

Taverna

Ueberheide

Liu

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

174

191

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Individual posttranslational modifications (PTMs) on histones have well established roles in certain biological processes, notably transcriptional programming. Recent genomewide studies describe patterns of covalent modifications, such as H3 methylation and acetylation at promoters of specific target genes, or ''bivalent domains,'' in stem cells, suggestive of a possible combinatorial interplay between PTMs on the same histone. However, detection of long-range PTM associations is often problematic in antibody-based or traditional mass spectrometric-based analyses. Here, histone H3 from a ciliate model was analyzed as an enriched source of transcriptionally active chromatin. Using a recently developed mass spectrometric approach, combinatorial modification states on single, long N-terminal H3 fragments (residues 1-50) were determined. The entire modification status of intact N termini was obtained and indicated correlations between K4 methylation and H3 acetylation. In addition, K4 and K27 methylation were identified concurrently on one H3 species. This methodology is applicable to other histones and larger polypeptides and will likely be a valuable tool in understanding the roles of combinatorial patterns of PTMs.bivalent domain ͉ electron transfer dissociation ͉ mass spectrometry ͉ posttranslational modifications ͉ Tetrahymena

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Section: Resultsmentioning

confidence: 88%

Long-distance combinatorial linkage between methylation and acetylation on histone H3 N termini

Taverna

Ueberheide

Liu

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

174

191

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“…Samples were loaded onto a 22% SDS-PAGE gel (60:0.4 acrylamide: bis-acrylamide) or for GLC7 experiments a 15% SDS-PAGE gel and blotted to polyvinylidene difluoride as described previously (29,30). Blots were blocked in 2-5% dry milk dissolved in 1ϫ TBST (0.15 M NaCl, 0.1 M Tris-HCl, pH7.5, 0.1%(w/v) Tween 20) for 2 h at room temperature or overnight at 4°C with agitation.…”

Section: Methodsmentioning

confidence: 99%

Site-specific Loss of Acetylation upon Phosphorylation of Histone H3

Edmondson¹,

Davie²,

Zhou³

et al. 2002

Journal of Biological Chemistry

102

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Post-translational modification of histones is a central aspect of gene regulation. Emerging data indicate that modification at one site can influence modification of a second site. As one example, histone H3 phosphorylation at serine 10 (Ser 10 ) facilitates acetylation of lysine 14 (Lys 14 ) by Gcn5 in vitro (1, 2). In vivo, phosphorylation of H3 precedes acetylation at certain promoters. Whether H3 phosphorylation globally affects acetylation, or whether it affects all acetylation sites in H3 equally, is not known. We have taken a genetic approach to this question by mutating Ser 10 in H3 to fix either a negative or a neutral charge at this position, followed by analysis of the acetylation states of the mutant histones using site-specific antibodies. Surprisingly, we find that conversion of Ser 10 to glutamate (S10E) or aspartate (S10D) causes almost complete loss of H3 acetylation at lysine 9 (Lys 9 ) in vivo. Acetylation of Lys 9 is also significantly reduced in cells bearing mutations in the Glc7 phosphatase that increase H3 phosphorylation levels. Mutation of Ser 10 in H3 and the concomitant loss of Lys 9 acetylation has minimal effects on expression of a Gcn5-dependent reporter gene. However, synergistic growth defects are observed upon loss of GCN5 in cells bearing H3 Ser 10 mutations that are reminiscent of delays in G 2 /M progression caused by combined loss of GCN5 and acetylation site mutations. Together these results demonstrate that H3 phosphorylation directly causes sitespecific and opposite changes in acetylation levels of two residues within this histone, Lys 9 and Lys 14 , and they highlight the importance of these histone modifications to normal cell functions.

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“…In classic experiments, deletion of the H3 N terminus was found to aberrantly activate transcription of a number of genes (44). This interesting biological result correlates with the long-standing observation that H3 exists in two pools in vivo, one full-length and the other as a proteolytically cleaved population (45). Histone H3 "clipping" is the term used to denote the process in which the H3 N-terminal tail is cleaved.…”

Section: Gdh1 Regulates Recruitment Of Sir Proteins To Silent Chromatmentioning

confidence: 63%

Functions for diverse metabolic activities in heterochromatin

Xue

Pillus

2016

Proc. Natl. Acad. Sci. U.S.A.

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Growing evidence demonstrates that metabolism and chromatin dynamics are not separate processes but that they functionally intersect in many ways. For example, the lysine biosynthetic enzyme homocitrate synthase was recently shown to have unexpected functions in DNA damage repair, raising the question of whether other amino acid metabolic enzymes participate in chromatin regulation. Using an in silico screen combined with reporter assays, we discovered that a diverse range of metabolic enzymes function in heterochromatin regulation. Extended analysis of the glutamate dehydrogenase 1 (Gdh1) revealed that it regulates silent information regulator complex recruitment to telomeres and ribosomal DNA. Enhanced N-terminal histone H3 proteolysis is observed in GDH1 mutants, consistent with telomeric silencing defects. A conserved catalytic Asp residue is required for Gdh1's functions in telomeric silencing and H3 clipping. Genetic modulation of α-ketoglutarate levels demonstrates a key regulatory role for this metabolite in telomeric silencing. The metabolic activity of glutamate dehydrogenase thus has important and previously unsuspected roles in regulating chromatin-related processes.I n eukaryotic nuclei, DNA is wrapped around histones to form nucleosomes, the basic subunits of chromatin (1). The physical and chemical properties of chromatin are regulated by at least two types of enzymatic activities: chromatin remodeling and posttranslational modifications of histones and chromatin-associated proteins (2, 3). These enzymatic activities directly determine the accessibility of DNA for transcription, replication, and repair.In Saccharomyces cerevisiae, three genomic regions are known to contain loci repressed by chromatin-related activities. These include the HM silent mating-type loci (HMR and HML), regions within the ribosomal DNA (rDNA), and some telomeres. Transcriptional silencing at these loci is established and maintained by a number of factors, including the Sirtuin class III deacetylase activity of silent information protein 2 (Sir2). Notably, Sir2 uses NAD + as a cofactor to deacetylate histones H3 and H4 in newly deposited nucleosomes. Other than Sir2, the composition of the silencing complexes and the mechanisms of silencing are different for the three silenced regions, with the telomeres and the HM loci more similar to each other and the rDNA locus having distinct features (reviewed in ref. 4). Silencing at telomeres and the HM loci was long considered to follow a sequential model: initial deacetylation by Sir2 creates binding sites for Sir3 and Sir4, which in turn regulate the spreading of Sir2 across these regions (5). More recent high-resolution studies report a less uniform landscape for silenced chromatin (6), although the central importance of the Sir proteins remains clear. They, together with transcription factors including Rap1 and Abf1, form a multisubunit silencing complex known as the silent information regulator (SIR) complex. Silencing at the rDNA locus does not involve the SIR complex but ra...

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Histone variants specific to the transcriptionally active, amitotically dividing macronucleus of the unicellular eucaryote, tetrahymena thermophila

Cited by 201 publications

References 28 publications

Long-distance combinatorial linkage between methylation and acetylation on histone H3 N termini

Long-distance combinatorial linkage between methylation and acetylation on histone H3 N termini

Site-specific Loss of Acetylation upon Phosphorylation of Histone H3

Functions for diverse metabolic activities in heterochromatin

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