Department of Molecular Biology, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.
Mol Cell. 2013 Oct 24;52(2):255-63. doi: 10.1016/j.molcel.2013.08.024. Epub 2013 Sep 19.
Chromatin remodelers have been implicated in the regulation of histone-modifying complexes. However, the underlying mechanism remains poorly understood. The Rpd3S histone deacetylase complex is recruited by elongating RNA polymerase II to remove histone acetylation at coding regions in a manner that is dependent on methylation of lysine 36 on histone 3 (H3K36me), and Rpd3S prefers dinucleosomes. Here, we show that the binding of Rpd3S to dinucleosomes and its catalytic activity are sensitive to the length of nucleosomal linker in a nonlinear fashion. Intriguingly, we found that H3K36me on one nucleosome stimulates Rpd3S to deacetylate the neighboring nucleosomes when those two nucleosomes are within an optimal distance. Finally, we demonstrate that chromatin remodelers enhance Rpd3S activity by altering nucleosomal spacing, suggesting that chromatin remodelers prime chromatin configuration to fine-tune subsequent histone modification reactions. This mechanism is important for accurate temporal control of chromatin dynamics during the transcription elongation cycle.
染色质重塑因子参与组蛋白修饰复合物的调节。然而,其潜在的机制仍知之甚少。Rpd3S 组蛋白去乙酰化酶复合物通过延伸的 RNA 聚合酶 II 募集,以依赖于组蛋白 3 上赖氨酸 36 的甲基化(H3K36me)的方式去除编码区域的组蛋白乙酰化,并且 Rpd3S 更喜欢二核小体。在这里,我们表明 Rpd3S 与二核小体的结合及其催化活性对核小体连接子的长度敏感,呈非线性方式。有趣的是,我们发现当两个核小体处于最佳距离时,一个核小体上的 H3K36me 刺激 Rpd3S 去乙酰化相邻的核小体。最后,我们证明染色质重塑因子通过改变核小体间距来增强 Rpd3S 的活性,这表明染色质重塑因子使染色质构象初始化为精细调节随后的组蛋白修饰反应。该机制对于转录延伸循环期间染色质动力学的精确时间控制很重要。