The Role of Histone H4 Biotinylation in the Structure of Nucleosomes

Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
PLoS ONE (Impact Factor: 3.23). 01/2011; 6(1):e16299. DOI: 10.1371/journal.pone.0016299
Source: PubMed


Post-translational modifications of histones play important roles in regulating nucleosome structure and gene transcription. It has been shown that biotinylation of histone H4 at lysine-12 in histone H4 (K12Bio-H4) is associated with repression of a number of genes. We hypothesized that biotinylation modifies the physical structure of nucleosomes, and that biotin-induced conformational changes contribute to gene silencing associated with histone biotinylation.
To test this hypothesis we used atomic force microscopy to directly analyze structures of nucleosomes formed with biotin-modified and non-modified H4. The analysis of the AFM images revealed a 13% increase in the length of DNA wrapped around the histone core in nucleosomes with biotinylated H4. This statistically significant (p<0.001) difference between native and biotinylated nucleosomes corresponds to adding approximately 20 bp to the classical 147 bp length of nucleosomal DNA.
The increase in nucleosomal DNA length is predicted to stabilize the association of DNA with histones and therefore to prevent nucleosomes from unwrapping. This provides a mechanistic explanation for the gene silencing associated with K12Bio-H4. The proposed single-molecule AFM approach will be instrumental for studying the effects of various epigenetic modifications of nucleosomes, in addition to biotinylation.

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Available from: Janos Zempleni
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    • "It is estimated that approximately 30 % of histone H4 molecules in telomeric repeats are biotinylated at position K12 (Hassan and Zempleni 2008). A recent study showed that K12 biotinylation in histone H4 alters the structure of the nucleosomes and leads to \15 % increase in the amount of DNA wrapped around nucleosomes (Filenko et al. 2011). Neurotox Res (2015) 27:172–197 179 The enrichment of H4K12bio depends on the concentration of biotin in the cell culture medium (Zempleni et al. 2009). "
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    • "Phosphopantetheinylation and biotinylation are two posttranslational modifications, which occur widely in living organisms, especially in metabolic enzymes to regulate their activity, such as aromatic carboxylic acid reductase, non-ribosomal peptide synthetases (NRPSs), polyketide synthases (PKSs) and carboxylases [16], [17], [18]. Biotinylation of histone H4 has been recently found to be involved in the regulation of nucleosome structure and gene transcription [19]. Biotinylation is also regarded as a useful protein tag in a variety of biochemical experiments [20], [21]. "
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    • "The di- NCP sample was imaged similarly to the mononucleosome sample described earlier [18] [19] [20] [21] [22]. Diluted samples (0.8 nM concentration in 10 mM Tris-HCl, Ph 7.5, and 4 mM MgCl 2 buffer) were deposited on APS mica and after drying, imaged in air at ambient conditions. "
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