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Nucleic Acids Res. 2012 Nov;40(21):10753-64. doi: 10.1093/nar/gks870. Epub 2012 Sep 24.

Transcriptional activation of yeast genes disrupts intragenic nucleosome phasing.

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  • 1Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Building 37, Room 3035A, Convent Dr., Bethesda, MD 20892, USA.

Abstract

Nucleosomes often undergo extensive rearrangement when genes are activated for transcription. We have shown previously, using paired-end sequencing of yeast nucleosomes, that major changes in chromatin structure occur when genes are activated by 3-aminotriazole (3AT), an inducer of the transcriptional activator Gcn4. Here, we provide a global analysis of these data. At the genomic level, nucleosomes are regularly phased relative to the transcription start site. However, for a subset of 234 strongly induced genes, this phasing is much more irregular after induction, consistent with the loss of some nucleosomes and the re-positioning of the remaining nucleosomes. To address the nature of this rearrangement, we developed the inter-nucleosome distance auto-correlation (DAC) function. At long range, DAC analysis indicates that nucleosomes have an average spacing of 162 bp, consistent with the reported repeat length. At short range, DAC reveals a 10.25-bp periodicity, implying that nucleosomes in overlapping positions are rotationally related. DAC analysis of the 3AT-induced genes suggests that transcription activation coincides with rearrangement of nucleosomes into irregular arrays with longer spacing. Sequence analysis of the +1 nucleosomes belonging to the 45 most strongly activated genes reveals a distinctive periodic oscillation in the A/T-dinucleotide occurrence that is present throughout the nucleosome and extends into the linker. This unusual pattern suggests that the +1 nucleosomes might be prone to sliding, thereby facilitating transcription.

PMID:
23012262
[PubMed - indexed for MEDLINE]
PMCID:
PMC3510488
Free PMC Article
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