Ribosome biogenesis is an essential cellular process that requires integration of extracellular cues, such as metabolic state, with intracellular signalling, transcriptional regulation and chromatin accessibility at the ribosomal DNA. Here, we demonstrate that the recently identified histone modification, methylation of H2AQ105 (H2AQ105me), is an integral part of a dynamic chromatin network at the rDNA locus. Its deposition depends on a functional mTor signalling pathway and acetylation of histone H3 at position K56, thus integrating metabolic and proliferative signals. Furthermore, we identify a first epigenetic reader of this modification, the ribonucleoprotein Nhp2, which specifically recognizes H2AQ105me. Based on functional and proteomic data, we suggest that Nhp2 functions as an adapter to bridge rDNA chromatin with components of the small subunit processome to efficiently coordinate transcription of rRNA with its post-transcriptional processing. We support this by showing that an H2AQ105A mutant has a mild defect in early processing of rRNA.

中文翻译：

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Nhp2 是 H2AQ105me 的阅读器，也是将新陈代谢与 rRNA 合成结合起来的网络的一部分

核糖体生物合成是一个重要的细胞过程，需要将细胞外信号（如代谢状态）与细胞内信号、转录调控和核糖体 DNA 染色质可及性整合起来。在这里，我们证明了最近发现的组蛋白修饰，即 H2AQ105 (H2AQ105me) 的甲基化，是 rDNA 基因座处动态染色质网络的组成部分。它的沉积取决于功能性 mTor 信号通路和 K56 位组蛋白 H3 的乙酰化，从而整合代谢和增殖信号。此外，我们确定了这种修饰的第一个表观遗传阅读器，即核糖核蛋白 Nhp2，它专门识别 H2AQ105me。基于功能和蛋白质组学数据，我们建议 Nhp2 作为接头将 rDNA 染色质与小亚基加工组的组分连接起来，以有效地协调 rRNA 的转录与其转录后加工。我们通过证明 H2AQ105A 突变体在 rRNA 的早期加工中存在轻微缺陷来支持这一点。