DNA Sequence-Dependent Contributions of Core Histone Tails to Nucleosome Stability: Differential Effects of Acetylation and Proteolytic Tail Removal

作者：Hans R. Widlund, Joseph M. Vitolo, Christophe Thiriet, Jeffrey J. Hayes · 发表于：Biochemistry · 年份：2000 · DOI：10.1021/bi991957l · 被引用次数：62 · 研究领域：Genomics and Chromatin Dynamics、RNA Interference and Gene Delivery、Protein Degradation and Inhibitors

Modulation of nucleosome stability in chromatin plays an important role in eukaryotic gene expression. The core histone N-terminal tail domains are believed to modulate the stability of wrapping nucleosomal DNA and the stability of the chromatin filament. We analyzed the contribution of the tail domains to the stability of nucleosomes containing selected DNA sequences that are intrinsically straight, curved, flexible, or inflexible. We find that the presence of the histone tail domains stabilizes nucleosomes containing DNA sequences that are intrinsically straight or curved. However, the tails do not significantly contribute to the free energy of nucleosome formation with flexible DNA. Interestingly, hyperacetylation of the core histone tail domains does not recapitulate the effect of tail removal by limited proteolysis with regard to nucleosome stability. We find that acetylation of the tails has the same minor effect on nucleosome stability for all the selected DNA sequences. A comparison of histone partitioning between long donor chromatin, acceptor DNA, and free histones in solution shows that the core histone tails mediate internucleosomal interactions within an H1-depleted chromatin fiber amounting to an average free energy of about 1 kcal/mol. Thus, such interactions would be significant with regard to the free energies of sequence-dependent nucleosome positioning. Last, we analyzed the contribution of the H2A/H2B dimers to nucleosome stability. We find that the intact...