Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Mol Cell. 2018 Nov 1;72(3):594-600.e2. doi: 10.1016/j.molcel.2018.09.030. Epub 2018 Oct 25.
The +1 nucleosome of yeast genes, within which reside transcription start sites, is characterized by histone acetylation, by the displacement of an H2A-H2B dimer, and by a persistent association with the RSC chromatin-remodeling complex. Here we demonstrate the interrelationship of these characteristics and the conversion of a nucleosome to the +1 state in vitro. Contrary to expectation, acetylation performs an inhibitory role, preventing the removal of a nucleosome by RSC. Inhibition is due to both enhanced RSC-histone interaction and diminished histone-chaperone interaction. Acetylation does not prevent all RSC activity, because stably bound RSC removes an H2A-H2B dimer on a timescale of seconds in an irreversible manner.
酵母基因的+1 核小体（其中包含转录起始位点）的特征是组蛋白乙酰化、H2A-H2B 二聚体的置换以及与 RSC 染色质重塑复合物的持续关联。在这里，我们证明了这些特征的相互关系以及核小体在体外向+1 状态的转化。与预期相反，乙酰化起到抑制作用，阻止 RSC 去除核小体。抑制作用既源于增强的 RSC-组蛋白相互作用，也源于减弱的组蛋白伴侣相互作用。乙酰化并不能阻止所有的 RSC 活性，因为稳定结合的 RSC 会以不可逆的方式在数秒内去除 H2A-H2B 二聚体。
