- Last Updated on Wednesday, 05 October 2011 14:23
Welcome to the companion page of our publication:
Nagarajan et al. 2010. PLoS Genetics. Natural Single-Nucleosome Epi-Polymorphisms in Yeast.
Nucleosomes are the basic units of chromatin, with part of the long DNA molecule wrapped around a multiprotein core, which makes unpacked chromatin often portrayed as a string of pearls. This string can carry three types of sequences: the genomic sequence of DNA (genome), the sequence of presence-or-absence of methylated cytosines (DNA epigenome) and, on every pearl, the presence-or-absence of any histone post-translational modification, such as methylation or acetylation of lysine residues (nucleosomal epigenome). These latter sequences can change dynamically, and the mechanisms involved are heavily studied as they participate in many physiological processes (pluripotency, disease…). However, nothing is known about the natural diversity of nucleosomal epigenomes in natural populations. As a model, we compared two unrelated yeast strains for their epigenome of one histone modification. We found a high divergence, which was enriched at regulatory sites and often carried on specific nucleosomes. Although it is widely known that nucleosome modifications are associated with gene expression, we observed that higher acetylation in one strain did not necessarily imply higher expression of the corresponding gene. However, we showed experimentally on one example that higher acetylation confers a stronger gene activation upon stimulation. These results suggest that nucleosomal epigenomes largely differ between individuals, raising essential questions on the origin of these differences and their contribution to personal responses to environmental changes (such as clinical treatments).
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