Stable nucleosome positioning and complete repression by the yeast alpha 2 repressor are disrupted by amino-terminal mutations in histone H4.

Roth, Sharon Y.; Shimizu, Mitsuhiro; Johnson, Lianna M.; Grunstein, Michael; Simpson, Robert T.

doi:10.1101/gad.6.3.411

Cited by 153 publications

(127 citation statements)

References 53 publications

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“…This is strongly supported by the observation that a deletion of the histone H2B cross-linking domain changes the minichromosome topology in vivo, suggesting that this domain is required for the proper folding of DNA in the nucleosome (63). Deletion or substitution of a single amino acid in the cross-linking domain of histone H4 alters chromatin structure in vivo (63)(64)(65)(66), decreases the ability of yeast to mate, increases the duration of S phase (67)(68)(69)(70), and affects telomeric repression (71,72) as well as expression of a large number of yeast genes (64,65,(73)(74)(75). It should be mentioned also that the cross-linking domain of histone H4 contains sites for post-translational acetylation and phosphorylation (76) that may also be involved in the regulation of the interaction of this domain with DNA at different levels of chromatin activity and condensation rendering nucleosomes competent for transcription and/or replication.…”

Section: The Change In Histone H2b/h4-dna Contacts Induced By Low Ionsupporting

confidence: 48%

Nucleosome Structural Transition during Chromatin Unfolding Is Caused by Conformational Changes in Nucleosomal DNA

Gavin¹,

Usachenko²,

Bavykin

1998

Journal of Biological Chemistry

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We have recently reported that certain core histone-DNA contacts are altered in nucleosomes during chromatin unfolding (Usachenko, S. I., Gavin I. M., and Bavykin, S. G. (1996) J. Biol. Chem. 271, 3831-3836). In this work, we demonstrate that these alterations are caused by a conformational change in the nucleosomal DNA. Using zero-length protein-DNA cross-linking, we have mapped histone-DNA contacts in isolated core particles at ionic conditions affecting DNA stiffness, which may change the nucleosomal DNA conformation. We found that the alterations in histone-DNA contacts induced by an increase in DNA stiffness in isolated core particles are identical to those observed in nucleosomes during chromatin unfolding. The change in the pattern of micrococcal nuclease digestion of linker histone-depleted chromatin at ionic conditions affecting chromatin compaction also suggests that the stretching of the linker DNA may alter the nucleosomal DNA conformation, resulting in a structural transition in the nucleosome which may play a role in rendering the nucleosome competent for transcription and/or replication.

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Section: The Change In Histone H2b/h4-dna Contacts Induced By Low Ionsupporting

confidence: 48%

Nucleosome Structural Transition during Chromatin Unfolding Is Caused by Conformational Changes in Nucleosomal DNA

Gavin¹,

Usachenko²,

Bavykin

1998

Journal of Biological Chemistry

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“…Analysis of deletions and single amino acid changes in the N-terminal region of histone H4 has demonstrated that certain changes in the H4 N terminus abolish repression of the yeast silent mating-type cassettes (35,36; see reference 25 for a review). Some of these H4 mutants also prevent efficient repression by the ␣2 repressor (60) and repression of genes adjacent to telomeres (2). Similar analysis has shown that deletion of a different but overlapping N-terminal region of H4 prevents efficient activation of the GAL1 and PHO5 genes (22), while deletions in the N-terminal tail of histone H3 lead to hyperactivation of the GAL1 gene (43).…”

mentioning

confidence: 63%

A New Class of Histone H2A Mutations in Saccharomyces cerevisiae Causes Specific Transcriptional Defects In Vivo

Hirschhorn

Bortvin

Ricupero-Hovasse

et al. 1995

Molecular and Cellular Biology

107

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Nucleosomes have been shown to repress transcription both in vitro and in vivo. However, the mechanisms by which this repression is overcome are only beginning to be understood. Recent evidence suggests that in the yeast Saccharomyces cerevisiae, many transcriptional activators require the SNF/SWI complex to overcome chromatin-mediated repression. We have identified a new class of mutations in the histone H2A-encoding gene HTA1 that causes transcriptional defects at the SNF/SWI-dependent gene SUC2. Some of the mutations are semidominant, and most of the predicted amino acid changes are in or near the N-and C-terminal regions of histone H2A. A deletion that removes the N-terminal tail of histone H2A also caused a decrease in SUC2 transcription. Strains carrying these histone mutations also exhibited defects in activation by LexA-GAL4, a SNF/SWI-dependent activator. However, these H2A mutants are phenotypically distinct from snf/swi mutants. First, not all SNF/SWI-dependent genes showed transcriptional defects in these histone mutants. Second, a suppressor of snf/swi mutations, spt6, did not suppress these histone mutations. Finally, unlike in snf/swi mutants, chromatin structure at the SUC2 promoter in these H2A mutants was in an active conformation. Thus, these H2A mutations seem to interfere with a transcription activation function downstream or independent of the SNF/SWI activity. Therefore, they may identify an additional step that is required to overcome repression by chromatin.In eukaryotic cells, DNA is complexed with histones and other proteins into chromatin (see reference 75 for a review). The primary component of chromatin is the nucleosome, which consists of approximately 146 bp of DNA wrapped around an octamer of histones (two histone H2A-H2B dimers and one [H3-H4] 2 tetramer; see reference 75 for a review). A growing body of evidence from both in vivo and in vitro studies has shown that the structure of chromatin influences gene expression (see references 25 and 53 for reviews). Biochemical experiments have shown that histones can repress transcription in vitro (see reference 53 for a review) and that transcriptional activators can overcome this repression (21,41,45,79,81,82). In vivo experiments in Saccharomyces cerevisiae have shown that the loss of transcriptional activators or of activator binding sites can be suppressed by mutations in histone genes (27,30,37,57). These results suggest that one function of transcriptional activators in vivo is to antagonize chromatin-mediated repression.In vivo studies of histone mutants have also suggested that histones play a variety of roles in transcriptional regulation. Small deletions and point mutations that alter the flexible N-terminal tails of different yeast histones have been shown to cause specific changes in transcription (see reference 25 for a review). Analysis of deletions and single amino acid changes in the N-terminal region of histone H4 has demonstrated that certain changes in the H4 N terminus abolish repression of the yeast silent mating-...

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“…Previous work has established that the MAT~2 repressor precisely positions an array of nucleosomes adjacent to its operator and has suggested that this nucleosome positioning plays an important role in the mechanism of transcriptional repression by MATe~2 (Shimizu et al 1991;Roth et al 1992). Because SSN6 and TUP1 are required for full repression of a cell-specific gene expression (Keleher et al 1992), we reasoned that these proteins might be involved in MAT~2-mediated nucleosome positioning.…”

Section: Resultsmentioning

confidence: 99%

The global transcriptional regulators, SSN6 and TUP1, play distinct roles in the establishment of a repressive chromatin structure.

Cooper¹,

Roth²,

Simpson³

1994

Genes Dev.

Self Cite

184

161

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Repression of a-cell specific gene expression in yeast ~ cells requires MATch2 and MCM1, as well as two global repressors, SSN6 and TUP1. Previous studies demonstrated that nucleosomes positioned adjacent to the a2/MCM1 operator in c~ cells directly contribute to repression. To investigate the possibility that SSN6 and TUP1 provide a link between MAT~2/MCM1 and neighboring histones, nucleosome locations were examined in ssn6 and t u p l ot cells. In both cases, nucleosome positions downstream of the operator were disrupted, and the severity of the disruption correlated with the degree of derepression. Nevertheless, the observed changes in chromatin structure were not dependent on transcription. Our data strongly indicate that SSN6 and TUP1 directly organize repressive regions of chromatin.

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Stable nucleosome positioning and complete repression by the yeast alpha 2 repressor are disrupted by amino-terminal mutations in histone H4.

Cited by 153 publications

References 53 publications

Nucleosome Structural Transition during Chromatin Unfolding Is Caused by Conformational Changes in Nucleosomal DNA

Nucleosome Structural Transition during Chromatin Unfolding Is Caused by Conformational Changes in Nucleosomal DNA

A New Class of Histone H2A Mutations in Saccharomyces cerevisiae Causes Specific Transcriptional Defects In Vivo

The global transcriptional regulators, SSN6 and TUP1, play distinct roles in the establishment of a repressive chromatin structure.

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