Department of Biology, Emory University, Atlanta, Georgia, United States of America.
PLoS Genet. 2010 Jun 3;6(6):e1000975. doi: 10.1371/journal.pgen.1000975.
Post-translational modifications of histone proteins modulate the binding of transcription regulators to chromatin. Studies in Drosophila have shown that the phosphorylation of histone H3 at Ser10 (H3S10ph) by JIL-1 is required specifically during early transcription elongation. 14-3-3 proteins bind H3 only when phosphorylated, providing mechanistic insights into the role of H3S10ph in transcription. Findings presented here show that 14-3-3 functions downstream of H3S10ph during transcription elongation. 14-3-3 proteins localize to active genes in a JIL-1-dependent manner. In the absence of 14-3-3, levels of actively elongating RNA polymerase II are severely diminished. 14-3-3 proteins interact with Elongator protein 3 (Elp3), an acetyltransferase that functions during transcription elongation. JIL-1 and 14-3-3 are required for Elp3 binding to chromatin, and in the absence of either protein, levels of H3K9 acetylation are significantly reduced. These results suggest that 14-3-3 proteins mediate cross-talk between histone phosphorylation and acetylation at a critical step in transcription elongation.
组蛋白蛋白的翻译后修饰调节转录调节剂与染色质的结合。果蝇的研究表明，JIL-1 对组蛋白 H3 的丝氨酸 10 位（H3S10ph）的磷酸化在早期转录延伸过程中是特异性所必需的。只有在磷酸化时，14-3-3 蛋白才能与 H3 结合，为 H3S10ph 在转录中的作用提供了机制上的见解。这里提出的发现表明，14-3-3 蛋白在转录延伸过程中在 H3S10ph 的下游起作用。14-3-3 蛋白以 JIL-1 依赖的方式定位于活跃的基因。在缺乏 14-3-3 的情况下，活跃延伸的 RNA 聚合酶 II 的水平严重降低。14-3-3 蛋白与延伸因子 3（Elp3）相互作用，Elp3 是一种在转录延伸过程中起作用的乙酰转移酶。JIL-1 和 14-3-3 蛋白是 Elp3 与染色质结合所必需的，在没有这两种蛋白的情况下，H3K9 乙酰化水平显著降低。这些结果表明，14-3-3 蛋白在转录延伸的关键步骤中介导组蛋白磷酸化和乙酰化之间的串扰。
