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Nucleosome structure(s) and stability: Variations on a theme

Howard Hughes Medical Institute and Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA.
Annual Review of Biophysics (Impact Factor: 12.25). 07/2010; 40(1):99-117. DOI: 10.1146/annurev-biophys-042910-155329
Source: PubMed

ABSTRACT Chromatin is a highly regulated, modular nucleoprotein complex that is central to many processes in eukaryotes. The organization of DNA into nucleosomes and higher-order structures has profound implications for DNA accessibility. Alternative structural states of the nucleosome, and the thermodynamic parameters governing its assembly and disassembly, need to be considered in order to understand how access to nucleosomal DNA is regulated. In this review, we provide a brief historical account of how the overriding perception regarding aspects of nucleosome structure has changed over the past thirty years. We discuss recent technical advances regarding nucleosome structure and its physical characterization and review the evidence for alternative nucleosome conformations and their implications for nucleosome and chromatin dynamics.

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    • "One mechanism includes changing the chemical composition of DNA by the addition of a methyl group that is usually associated with transcriptional repression (Fig. 1) (Smith and Meissner 2013). DNA is wrapped around eight histone proteins to form nucleosomes (Fig. 2A), and a second mechanism involves modifying specific amino acid residues on the histone tails (Fig. 2B) (Andrews and Luger 2011). These posttranslational histone modifications are able to recruit additional proteins that either positively or negatively affect transcription (Fig. 2C) (Barski et al. 2007; Wang et al. 2008). "
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    Cold Spring Harbor Perspectives in Medicine 02/2014; 4(2). DOI:10.1101/cshperspect.a015263 · 7.56 Impact Factor
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    • "If there are real differences in the DNA binding affinities or binding site sizes for the H1.1, H1.4 and H1 0 proteins, the differences must be attributed to the different sequences and/or charge and charge distribution in the C-terminal domains of these proteins. It is generally accepted that H1, or linker histone, binds to DNA as it enters and/or exits the nucleosome [10] [11] [12] [13]. Two different models for H1 binding place the H1 protein across the nucleosome with H1 interacting with two or three patches of the nucleosomal DNA on the same side of the nucleosome [14] or alternatively locate the H1 so that it binds to a continuous and more linear linker DNA region [15]. "
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    • "Eukaryotic genome is organized into distinct chromosomes that are formed by a nucleoprotein complex called chromatin. Chromatin consists of the nucleosomes, in which 147 base-pairs of genomic DNA form a loop around the histone octamer core represented by two molecules of each core histone (H2A, H2B, H3 and H4) (Andrews and Luger, 2011). Nucleosomes are connected by non-histone associated linker DNA of approximately 10-80 bp length resulting in a formation of the " beads on the string " structures, which are folded into 30 nm fiber (Felsenfeld and Groudine, 2003). "
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