Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
Mol Cell. 2010 Jul 30;39(2):234-46. doi: 10.1016/j.molcel.2010.07.003.
Methylation of histone H3 by Set1 and Set2 is required for deacetylation of nucleosomes in coding regions by histone deacetylase complexes (HDACs) Set3C and Rpd3C(S), respectively. We report that Set3C and Rpd3C(S) are cotranscriptionally recruited in the absence of Set1 and Set2, but in a manner stimulated by Pol II CTD kinase Cdk7/Kin28. Consistently, Rpd3C(S) and Set3C interact with Ser5-phosphorylated Pol II and histones in extracts, but only the histone interactions require H3 methylation. Moreover, reconstituted Rpd3C(S) binds specifically to Ser5-phosphorylated CTD peptides in vitro. Hence, whereas interaction with methylated H3 residues is required for Rpd3C(S) and Set3C deacetylation activities, their cotranscriptional recruitment is stimulated by the phosphorylated CTD. We further demonstrate that Rpd3, Hos2, and Hda1 have overlapping functions in deacetylating histones and suppressing cotranscriptional histone eviction. A strong correlation between increased acetylation and lower histone occupancy in HDA mutants implies that histone acetylation is important for nucleosome eviction.
组蛋白 H3 的甲基化由 Set1 和 Set2 完成，分别负责组蛋白去乙酰化酶复合物（HDACs）Set3C 和 Rpd3C(S)对编码区核小体的去乙酰化。我们报告称，在没有 Set1 和 Set2 的情况下，Set3C 和 Rpd3C(S) 可被转录共募集，但需要 Pol II CTD 激酶 Cdk7/Kin28 的刺激。一致地，Rpd3C(S) 和 Set3C 在提取物中与 Ser5 磷酸化的 Pol II 和组蛋白相互作用，但只有组蛋白相互作用需要 H3 甲基化。此外，体外重建的 Rpd3C(S) 特异性结合 Ser5 磷酸化的 CTD 肽。因此，尽管与甲基化的 H3 残基的相互作用对于 Rpd3C(S) 和 Set3C 的去乙酰化活性是必需的，但它们的转录共募集受到磷酸化 CTD 的刺激。我们进一步证明，Rpd3、Hos2 和 Hda1 在去乙酰化组蛋白和抑制转录共逐出组蛋白方面具有重叠功能。在 HDA 突变体中，乙酰化增加和组蛋白占有率降低之间存在很强的相关性，这表明组蛋白乙酰化对于核小体逐出很重要。
