Telomeric repeats act as nucleosome-disfavouring sequences in vivo

Yuichi Ichikawa, Nobuyuki Morohashi, Yoshifumi Nishimura, Hitoshi Kurumizaka, Mitsuhiro Shimizu

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    Abstract

    Telomeric DNAs consist of tandem repeats of G-clusters such as TTAGGG and TG1-3, which are the human and yeast repeat sequences, respectively. In the yeast Saccharomyces cerevisiae, the telomeric repeats are non-nucleosomal, whereas in humans, they are organized in tightly packaged nucleosomes. However, previous in vitro studies revealed that the binding affinities of human and yeast telomeric repeat sequences to histone octamers in vitro were similar, which is apparently inconsistent with the differences in the human and yeast telomeric chromatin structures. To further investigate the relationship between telomeric sequences and chromatin structure, we examined the effect of telomeric repeats on the formation of positioned nucleosomes in vivo by indirect end-label mapping, primer extension mapping and nucleosome repeat analyses, using a defined minichromosome in yeast cells. We found that the human and yeast telomeric repeat sequences both disfavour nucleosome assembly and alter nucleosome positioning in the yeast minichromosome. We further demonstrated that the G-clusters in the telomeric repeats are required for the nucleosomedisfavouring properties. Thus, our results suggest that this inherent structural feature of the telomeric repeat sequences is involved in the functional dynamics of the telomeric chromatin structure.

    Original languageEnglish
    Pages (from-to)1541-1552
    Number of pages12
    JournalNucleic Acids Research
    Volume42
    Issue number3
    DOIs
    Publication statusPublished - 2014 Feb

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    ASJC Scopus subject areas

    • Genetics

    Cite this

    Ichikawa, Y., Morohashi, N., Nishimura, Y., Kurumizaka, H., & Shimizu, M. (2014). Telomeric repeats act as nucleosome-disfavouring sequences in vivo. Nucleic Acids Research, 42(3), 1541-1552. https://doi.org/10.1093/nar/gkt1006