Acetylation of Histone H3 at the Nucleosome Dyad Alters DNA-Histone Binding
Acetylation of Histone H3 at the Nucleosome Dyad Alters DNA-Histone Binding
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DOI：
10.1074/jbc.m109.003202
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发表时间：
2009-08-28
影响因子：
4.8
通讯作者：
Ottesen, Jennifer J.
中科院分区：
文献类型：
--
作者：
Manohar, Mridula;Mooney, Alex M.;Ottesen, Jennifer J.
组蛋白翻译后修饰对于调节和促进生物过程，如RNA转录和DNA修复是必不可少的。有15个修饰位于DNA-组蛋白二联体界面，包括H3-K115(H3-K115Ac)和H3-K122(H3-K122Ac)的乙酰化，但这些修饰的功能后果尚不清楚。我们通过表达的蛋白质连接制备了半合成的组蛋白H3，在Lys-115和/或Lys-122上乙酰化，并将它们整合到单个核小体中。竞争性重组分析表明，H3-K115和H3-K122的乙酰化降低了组蛋白八聚体结合的自由能。限制性内切酶动力学分析表明，这些组蛋白修饰不会改变修饰位点附近的DNA可及性。然而，H3-K122的乙酰化增加了热重定位的速度。值得注意的是，用于模拟赖氨酸乙酰化的Lys-&Gt；Gln替换突变并不能完全复制H3-K115Ac或H3-K122Ac修饰的效果。我们的结果与结论一致，即二联体界面上的乙酰化减少了DNA组蛋白相互作用(S)，这可能有助于核小体重新定位和/或组装/拆卸。
Histone post-translational modifications are essential for regulating and facilitating biological processes such as RNA transcription and DNA repair. Fifteen modifications are located in the DNA-histone dyad interface and include the acetylation of H3-K115 (H3-K115Ac) and H3-K122 (H3-K122Ac), but the functional consequences of these modifications are unknown. We have prepared semisynthetic histone H3 acetylated at Lys-115 and/or Lys-122 by expressed protein ligation and incorporated them into single nucleosomes. Competitive reconstitution analysis demonstrated that the acetylation of H3-K115 and H3-K122 reduces the free energy of histone octamer binding. Restriction enzyme kinetic analysis suggests that these histone modifications do not alter DNA accessibility near the sites of modification. However, acetylation of H3-K122 increases the rate of thermal repositioning. Remarkably, Lys -> Gln substitution mutations, which are used to mimic Lys acetylation, do not fully duplicate the effects of the H3-K115Ac or H3-K122Ac modifications. Our results are consistent with the conclusion that acetylation in the dyad interface reduces DNA-histone interaction(s), which may facilitate nucleosome repositioning and/or assembly/disassembly.