Regular arrangement of nucleosomes on 5S rRNA genes in Xenopus laevis.

Young, Dallan; Carroll, Dana

doi:10.1128/mcb.3.4.720

Cited by 35 publications

(29 citation statements)

References 53 publications

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“…Earlier work had demonstrated that removal of histone H1 was all that was required for transcription factors to activate the oocyte 5S rRNA genes in somatic nuclei (12,76). The in vitro positioning that we obtain in the presence of histone H1 on the oocyte 5S rRNA genes is consistent with the low-resolution in vivo mapping on nucleosomes on these repeats in the chromosome of somatic cells (12,29,119). In our earlier studies, we concluded that the addition of histone H1 directed the positioning of a nucleosome over the oocyte 5S rRNA gene (12).…”

Section: Discussionsupporting

confidence: 71%

“…4) (34,36,66). Even though our experiments employ a single nucleosome, the key binding sites (ϩ81 to ϩ91) for TFIIIA would be predicted to remain accessible within the 40-to 50-bp linker DNA present in the somatic 5S rRNA gene nucleosomal repeat (119). A final point is histone H1 binds selectively to nucleosomal DNA compared to naked DNA (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Role of Histone H1 as an Architectural Determinant of Chromatin Structure and as a Specific Repressor of Transcription onXenopus Oocyte 5S rRNA Genes

Sera¹,

Wolffe²

1998

Molecular and Cellular Biology

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We explore the role of histone H1 as a DNA sequence-dependent architectural determinant of chromatin structure and of transcriptional activity in chromatin. The Xenopus laevis oocyte-and somatic-type 5S rRNA genes are differentially transcribed in embryonic chromosomes in vivo depending on the incorporation of somatic histone H1 into chromatin. We establish that this effect can be reconstructed at the level of a single nucleosome. H1 selectively represses oocyte-type 5S rRNA genes by directing the stable positioning of a nucleosome such that transcription factors cannot bind to the gene. This effect does not occur on the somatic-type genes. Histone H1 binds to the 5 end of the nucleosome core on the somatic 5S rRNA gene, leaving key regulatory elements in the promoter accessible, while histone H1 binds to the 3 end of the nucleosome core on the oocyte 5S rRNA genes, specifically blocking access to a key promoter element (the C box). TFIIIA can bind to the somatic 5S rRNA gene assembled into a nucleosome in the presence of H1. Because H1 binds with equivalent affinities to nucleosomes containing either gene, we establish that it is the sequence-selective assembly of a specific repressive chromatin structure on the oocyte 5S rRNA genes that accounts for differential transcriptional repression. Thus, general components of chromatin can determine the assembly of specific regulatory nucleoprotein complexes.Determination of the structure of eukaryotic transcription factors has led to the recognition that several DNA recognition motifs are shared with proteins that are conventionally viewed as having the general function of packaging the vast majority of DNA within the chromosome (61,71,105). These similarities occur between the core histones and particular TATA binding protein-associated factors within transcription factor TFIID (3, 9, 118), between linker histones and sequence-specific DNA binding proteins such as hepatocyte nuclear factor 3 (HNF3) (15,72), and between high-mobility-group HMG1 and DNA binding proteins such as the human sex-determining factor SRY (73,103,105). The proteins that package DNA into the chromosome do so by bending or wrapping the double helix. Transcription factors that share structural features with histones or HMG proteins might function as architectural determinants that remodel DNA to facilitate the assembly of higher-order nucleoprotein structures that activate or repress transcription (4,24,26,30,31,51,109). HNF3, which contains a winged-helix motif similar to that found in histone H1, can replace H1 in the chromatin of the mouse serum albumin enhancer (53, 54). HNF3 contributes to the positioning of nucleosomes on this regulatory DNA (14, 81, 111).The core histones, linker histones, and HMG proteins could also contribute to the assembly of specific regulatory nucleoprotein architectures through structure-and sequence-selective interactions with DNA (87, 109, 112). Core histones may selectively recognize both DNA structure such as curvature (83, 112) and sequence (25, 101). Sequence-...

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Section: Discussionsupporting

confidence: 71%

Section: Discussionmentioning

confidence: 99%

Role of Histone H1 as an Architectural Determinant of Chromatin Structure and as a Specific Repressor of Transcription onXenopus Oocyte 5S rRNA Genes

Sera¹,

Wolffe²

1998

Molecular and Cellular Biology

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“…Removal of histone H1 from somatic cell chromatin allows transcription factors to gain access to the oocyte type 5S rRNA genes. The oocyte 5S rRNA genes in somatic cells in vivo are known to be packaged into nucleosomes (Gottesfeld and Bloomer 1980;Young and Carroll 1983) and the positioning of histone-DNA contacts appears dependent on histone H1 (Chipev and Wolffe 1992). Sliding of nucleosomes following H1 removal may allow transcription factors access to the oocyte 5S rRNA genes.…”

Section: Histone H1 and The Selective Repression Of The Oocyte 5s Rrnmentioning

confidence: 99%

Specific regulation of Xenopus chromosomal 5S rRNA gene transcription in vivo by histone H1.

Bouvet

Dimitrov²,

Wolffe³

1994

Genes Dev.

233

154

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The incorporation of histone H1 into chromatin during embryogenesis directs the specific repression of the Xenopus oocyte 5S rRNA genes. An increase in histone H1 content specifically restricts TFIIIA-activated transcription, and a decrease in histone HI within chromatin facilitates the activation of the oocyte 5S rRNA genes by TFIIIA. Variation in the amount of histone HI in chromatin does not significantly influence somatic 5S rRNA gene transcription. Thus, the regulated expression of histone HI during Xenopus development has a specific and dominant role in mediating the differential expression of the oocyte and somatic 5S rRNA genes. This example demonstrates that histones can exert dominant repressive effects on the transcription of a gene in vivo in spite of an abundance of transcription factors for that gene.

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“…2B} for both templates. Nucleosomes are assembled with a physiological spacing of -180-190 bp (Young and Carroll 1983). No major changes in chromatin organization occur between 4 and 16 hr, although large differences in transcriptional activity occur between initially single-or double-stranded templates over this time interval {see Fig.…”

Section: Chromatin Assembly On Replicating Single-stranded and Nonrepmentioning

confidence: 99%

Replication-coupled chromatin assembly is required for the repression of basal transcription in vivo.

Almouzni¹,

Wolffe²

1993

Genes Dev.

158

124

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The chromatin assembly process coupled to DNA synthesis in the Xenopus oocyte nucleus is significantly more repressive toward basal transcription than chromatin assembly on duplex DNA. We show that chromatin assembly concurrent with DNA synthesis over the promoter region itself is causal for repression.However, the trans-activator GaI4-VP16 both relieves repression and activates transcription regardless of the chromatin assembly pathway. This activation is independent of whether GaI4-VP16 addition occurs before or after chromatin assembly. We propose that replication-coupled chromatin assembly represents a general mechanism to direct the efficient repression of basal transcription. However transcription induction by a specific activator, GaI4-VP16, occurs independent of this chromatin-mediated repression.

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Regular arrangement of nucleosomes on 5S rRNA genes in Xenopus laevis.

Cited by 35 publications

References 53 publications

Role of Histone H1 as an Architectural Determinant of Chromatin Structure and as a Specific Repressor of Transcription onXenopus Oocyte 5S rRNA Genes

Role of Histone H1 as an Architectural Determinant of Chromatin Structure and as a Specific Repressor of Transcription onXenopus Oocyte 5S rRNA Genes

Specific regulation of Xenopus chromosomal 5S rRNA gene transcription in vivo by histone H1.

Replication-coupled chromatin assembly is required for the repression of basal transcription in vivo.

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