Department of Medical Genetics, Haematology, and Pathology, School of Medicine, Cardiff University, Cardiff, UK.
PLoS Genet. 2011 Jun;7(6):e1002124. doi: 10.1371/journal.pgen.1002124. Epub 2011 Jun 16.
Global genome nucleotide excision repair removes DNA damage from transcriptionally silent regions of the genome. Relatively little is known about the molecular events that initiate and regulate this process in the context of chromatin. We've shown that, in response to UV radiation-induced DNA damage, increased histone H3 acetylation at lysine 9 and 14 correlates with changes in chromatin structure, and these alterations are associated with efficient global genome nucleotide excision repair in yeast. These changes depend on the presence of the Rad16 protein. Remarkably, constitutive hyperacetylation of histone H3 can suppress the requirement for Rad7 and Rad16, two components of a global genome repair complex, during repair. This reveals the connection between histone H3 acetylation and DNA repair. Here, we investigate how chromatin structure is modified following UV irradiation to facilitate DNA repair in yeast. Using a combination of chromatin immunoprecipitation to measure histone acetylation levels, histone acetylase occupancy in chromatin, MNase digestion, or restriction enzyme endonuclease accessibility assays to analyse chromatin structure, and finally nucleotide excision repair assays to examine DNA repair, we demonstrate that global genome nucleotide excision repair drives UV-induced chromatin remodelling by controlling histone H3 acetylation levels in chromatin. The concerted action of the ATPase and C3HC4 RING domains of Rad16 combine to regulate the occupancy of the histone acetyl transferase Gcn5 on chromatin in response to UV damage. We conclude that the global genome repair complex in yeast regulates UV-induced histone H3 acetylation by controlling the accessibility of the histone acetyl transferase Gcn5 in chromatin. The resultant changes in histone H3 acetylation promote chromatin remodelling necessary for efficient repair of DNA damage. Recent evidence suggests that GCN5 plays a role in NER in human cells. Our work provides important insight into how GG-NER operates in chromatin.
全球基因组核苷酸切除修复可从基因组转录沉默区域去除 DNA 损伤。然而，对于在染色质背景下启动和调节这一过程的分子事件，我们知之甚少。我们已经表明，在响应 UV 辐射诱导的 DNA 损伤时，组蛋白 H3 在赖氨酸 9 和 14 上的乙酰化增加与染色质结构的变化相关，这些变化与酵母中有效的全球基因组核苷酸切除修复相关。这些变化依赖于 Rad16 蛋白的存在。值得注意的是，组蛋白 H3 的组成型过度乙酰化可以抑制 Rad7 和 Rad16（全球基因组修复复合物的两个组成部分）在修复过程中的需求。这揭示了组蛋白 H3 乙酰化与 DNA 修复之间的联系。在这里，我们研究了染色质结构在 UV 照射后如何被修饰以促进酵母中的 DNA 修复。我们使用组合染色质免疫沉淀来测量组蛋白乙酰化水平、组蛋白乙酰转移酶在染色质中的占据、MNase 消化或限制酶内切酶可及性分析来分析染色质结构，最后进行核苷酸切除修复分析来检查 DNA 修复，我们证明全球基因组核苷酸切除修复通过控制染色质中组蛋白 H3 乙酰化水平来驱动 UV 诱导的染色质重塑。Rad16 的 ATP 酶和 C3HC4 RING 结构域的协同作用结合起来，调节组蛋白乙酰转移酶 Gcn5 在染色质上的占据，以响应 UV 损伤。我们得出结论，酵母中的全球基因组修复复合物通过控制染色质中组蛋白乙酰转移酶 Gcn5 的可及性来调节 UV 诱导的组蛋白 H3 乙酰化。组蛋白 H3 乙酰化的这种变化促进了有效的 DNA 损伤修复所必需的染色质重塑。最近的证据表明，GCN5 在人类细胞的 NER 中发挥作用。我们的工作为 GG-NER 在染色质中如何运作提供了重要的见解。
