Accueil du site > Animations Scientifiques > Séminaires 2007 > Histone H1 is a architectural molecule required for chromatin compaction, and is redundant for gene repression
Histone H1 is a architectural molecule required for chromatin compaction, and is redundant for gene repression
Orateur :
Hugh Patterton, Laboratory of Epigenomics and DNA Function, Department of Biotechnology, University of the Free State, Bloemfontein, South Africa
Salle :
118
Sujet :
The linker histone binds to the outside of the nucleosome core, straddling two gyres of nucleosomal DNA at the entry/exit points of the nucleosome, and contacting the DNA close to the dyad axis and within the last helical turn of the nucleosome. The yeast Saccharomyces cerevisiae, a unicellular eukaryote, contains a single copy of the linker histone, Hho1p. This linker histone is unusual in that it contains two single winged helix motif globular domains, separated by a lysine-rich region. We have shown that Hho1p can bind to two four-way junction DNA molecules simultaneously, suggesting that Hho1p may contact two adjacent nucleosomes when bound to chromatin.
We have also shown that, although the level of Hho1p protein remained constant from exponential phase to stationary phase, Hho1p binds to chromatin preferentially during stationary phase. Microarray analysis of gene expression in stationary phase showed that all genes were expressed at significantly lower levels and that this genome-wide repression did nor require Hho1p. Further microarray analysis at 15min, 30min, 1h and 2h time points showed that although the genes on some chromosomes became activated in domains, no similar Hho1p-dependent domains could be identified, suggesting that Hho1p was not involved in domain-wide gene regulation. We next performed a chip-on-chip analysis, and showed that Hho1p was evenly distributed throughout the genome in stationary phase. There was no evidence for the preferential binding of Hho1p to AT-rich regions or silenced regions during exponential phase. We also investigated chromatin compaction in stationary and exponential phase in a genome-wide fashion, and showed that chromatin was evenly compacted during stationary phase, and that this compaction required the presence of Hho1p.
Dans la même rubrique :
- Discrete breathers in nonlinear network models of proteins
- Conservative behavior of the biological complex system [Telomeres-Telomerase-Prolifération]
- Linking molecular mechanisms to the organism’s physiology using transcriptomics
- Electron-donor modified nanoparticles for selected cell labeling and photodynamic therapy
- Soutenance d’HDR:Les modes normaux de basse fréquence des protéines
- Human monoclonal antibodies against viruses and cancer
- Vésicules biomimétiques à base de PIP2 pour étudier des interactions protéines membranes : application à une protéine de la famille des ERM (ezrine, radixine, moésine).
- Structural insights into base damage recognition and removal by the Fpg DNA glycosylase
- Transcription by yeast RNA polymerase III and Chromatin Remodeling
- Distinct roles of core histones, histone variants and linker histones in chromatin function
- DNA : More than just a ladder
- Chromatin dynamics in interphase
- On the role of the retroviral Gag protein and the RNA in virus assembly
- What determines the size of virus ?
- Cytoskeleton dynamics involved in cell morphology control and multicellular stability
- Molecular mechanisms of gene transcription and DNA repair in living cells
- Models for the interaction between antibiotic peptides and lipid bilayers - Modèles pour l’interaction entre des peptides antibiotiques et des bicouches lipidiques
- Small Molecule Modulators of Chromatin Modifying Enzymes : To Probe Eukaryotic Transcription and To Target Diseases
- Exploration électrochimique de la dynamique de brins courts d’ADN ancrés sur une surface
- The nucleosome : A transparent, slippery, sticky and yet stable DNA-protein complex