Search results for "Nucleosome"

Gcn5p is involved in the acetylation of histone H3 in nucleosomes.

1997

Abstract Enzymatic extracts from a gcn5 mutant and wild-type strains of Saccharomyces cerevisiae were chromatographically fractionated and the histone acetyltransferase activities compared. When free histones were used as substrate, extracts from wild-type cells showed two peaks of activity on histone H3 but extracts from gcn5 mutant cells showed only one. With nucleosomes as substrate, the histone acetyltransferase activities present in extracts from the gcn5 mutant strain were not able to modify H3 whereas wild-type cell extracts acetylated intensely this histone. The activity that acetylated nucleosome-bound H3 behaved as a 170-kDa complex. We suggest that Gcn5p represents a catalytic su…

Electrophoretic separation of a class of nucleosomes enriched in HMG 14 and 17 and actively transcribed globin genes.

1980

Monomer nucleosomes from chick erythrocytes can be fractionated according to their electrophoretic mobility in (comparatively) high salt acrylamide gels. We show that the fractionation is based predominantly on differences in charge. The monomer heterogeneity persists even when the nucleosomes are trimmed down to 145 bp with Exo III or when H1 and H5 are removed. The slowest migrating monomers are associated with HMG 14 and 17; however, we do not believe that these proteins are entirely responsible for the altered mobility since the nucleosome heterogeneity persists even after removal of HMG 14 and 17. The DNA associated with the HMG 14 and 17 containing nucleosomes is shown to be enriched …

A multi-layer method to study genome-scale positions of nucleosomes

2009

AbstractThe basic unit of eukaryotic chromatin is the nucleosome, consisting of about 150 bp of DNA wrapped around a protein core made of histone proteins. Nucleosomes position is modulated in vivo to regulate fundamental nuclear processes. To measure nucleosome positions on a genomic scale both theoretical and experimental approaches have been recently reported. We have developed a new method, Multi-Layer Model (MLM), for the analysis of nucleosome position data obtained with microarray-based approach. The MLM is a feature extraction method in which the input data is processed by a classifier to distinguish between several kinds of patterns. We applied our method to simulated-synthetic and…

Promoter-Targeted Histone Acetylation of Chromatinized Parvoviral Genome Is Essential for the Progress of Infection

2015

ABSTRACT The association of host histones with parvoviral DNA is poorly understood. We analyzed the chromatinization and histone acetylation of canine parvovirus DNA during infection by confocal imaging and in situ proximity ligation assay combined with chromatin immunoprecipitation and high-throughput sequencing. We found that during late infection, parvovirus replication bodies were rich in histones bearing modifications characteristic of transcriptionally active chromatin, i.e., histone H3 lysine 27 acetylation (H3K27ac). H3K27ac, in particular, was located in close proximity to the viral DNA-binding protein NS1. Importantly, our results show for the first time that in the chromatinized …

Presence of nucleosomes inPenicillium chrysogenum

1987

We have studied the chromatin structure ofPenicillium chrysogenum. This fungus presents the typical nucleosomal repeat and the core DNA size characteristic of all the eukaryotes. The repeat length (about 180 base pairs) is in the range of those obtained for most fungi (160–180 base pairs) and shorter than in higher eukaryotes. Knowledge aboutP. chrysogenum chromatin structure opens the way to the study of the mechanisms of genetic regulation in this filamentous fungus.

Chromatin structure of yeast genes.

1989

Histone-mediated transgenerational epigenetics

2019

Abstract Epigenetic mechanisms operate at the interface between the environment and genome, by converting the environmental stimuli to phenotypic responses through changes in the chromatin landscape, which ultimately affects gene expression in the absence of alterations in DNA sequence. In this scenario, transgenerational inheritance occurs when epigenetic variations induced by environmental stimuli are transmitted through the germ line to succeeding generations that had never experienced those stimuli. There is an ever-growing list of reports indicating that histones are fundamental players in these processes in a variety of organisms. In this chapter, we provide a perspective on histone-d…

Genome-wide characterization of chromatin binding and nucleosome spacing activity of the nucleosome remodelling ATPase ISWI

2011

The evolutionarily conserved ATP-dependent nucleosome remodelling factor ISWI can space nucleosomes affecting a variety of nuclear processes. In Drosophila, loss of ISWI leads to global transcriptional defects and to dramatic alterations in higher-order chromatin structure, especially on the male X chromosome. In order to understand if chromatin condensation and gene expression defects, observed in ISWI mutants, are directly correlated with ISWI nucleosome spacing activity, we conducted a genome-wide survey of ISWI binding and nucleosome positioning in wild-type and ISWI mutant chromatin. Our analysis revealed that ISWI binds both genic and intergenic regions. Remarkably, we found that ISWI…

Gene expression during early embryogenesis of sea urchin: The histone and homeobox genes

1997

Transcriptional regulators are thought to play a key role in cell fate determination and territorial specification in sea urchin. Our goals are to clone transcription factors for studying embryonic development. One approach has been to use promoter binding and gene transfer technology to investigate the mechanisms of transcriptional activation and repression of the early H2A histone gene. By this analysis we identified a transcriptional activator, the MBF-1, that binds to the modulator element of the H2A gene and enhances the activity of the H2A promoter. However, the enhancer activity of the modulator and its interaction with MBF-1 also occurs at the gastrula stage when the early histone g…

Transcriptional and Structural Study of a Region of Two Convergent Overlapping Yeast Genes

1999

The exceptionally close packing of many yeast genes and other chromosomal elements raises the question of how those elements are functionally insulated. All published work shows that natural insulators are very effective, but transcriptional interference (TI) occurs if they are mutated or if their natural context is altered. Mechanisms to avoid TI are poorly understood, but are thought to involve an interplay of cis sequences and trans factors in a chromatin context. We have studied the case of two convergent closely packed ORFs (56 bp of separation) in chromosome IX of Saccharomyces cerevisiae. mRNAs from POT1 and YIL161w overlap by up to 115 nt. Convergent transcription causes a small but…