H3K79me3 ChIP-Seq at FRB-Pyk1 and WT strains under addition of DMSO treatment

The glycolytic enzyme, pyruvate kinase Pyk1 maintains telomere heterochromatin by phosphorylating histone H3T11 (H3pT11), which promotes SIR (silent information regulator) complex binding at telomeres and prevents autophagy-mediated Sir2 degradation. However, the exact action mechanism of H3pT11 is poorly understood. Here, we identify Dot1-catalyzed H3K79 tri-methylation (H3K79me3) as the downstream effector of H3pT11 and uncover how this histone crosstalk regulates autophagy and telomere silencing. Mechanistically, Pyk1-catalyzed H3pT11 directly reduces the binding of Dot1 to chromatin and inhibits Dot1-catalyzed H3K79me3, which leads to transcriptional repression of autophagy genes and reduced autophagy. Despite the antagonism between H3pT11 and H3K79me3, they synergically promote the binding of SIR complex at telomeres to maintain telomere silencing. Furthermore, we identify Reb1 as a telomere-associated factor that recruits Pyk1-containing SESAME (Serine-responsive SAM-containing Metabolic Enzyme) complex to telomere regions to phosphorylate H3T11 and prevent the invasion of H3K79me3 from euchromatin into heterochromatin to maintain telomere silencing. Together, these results uncover a novel histone crosstalk and provide insights into dynamic regulation of silent heterochromatin and autophagy in response to cell metabolism.糖酵解酶丙酮酸激酶Pyk1通过催化组蛋白H3T11磷酸化（H3pT11）维持端粒异染色质：该修饰可促进沉默信息调节因子（silent information regulator, SIR）复合物在端粒区域的结合，并阻断自噬介导的Sir2降解。然而，目前学界对H3pT11的确切作用机制仍不甚明晰。本研究鉴定出Dot1催化的组蛋白H3K79三甲基化（H3K79me3）为H3pT11的下游效应因子，并揭示了这一组蛋白串扰如何调控自噬与端粒沉默过程。机制层面，Pyk1催化产生的H3pT11可直接降低Dot1与染色质的结合亲和力，抑制Dot1介导的H3K79me3修饰，进而引发自噬相关基因的转录抑制，并最终降低细胞自噬水平。尽管H3pT11与H3K79me3之间存在拮抗关系，但二者可协同促进SIR复合物在端粒区域的招募与结合，以维持端粒沉默状态。此外，本研究鉴定出端粒相关因子Reb1可招募携带丝氨酸响应型含SAM代谢酶（Serine-responsive SAM-containing Metabolic Enzyme, SESAME）复合物的Pyk1至端粒区域，通过催化H3T11磷酸化，阻止H3K79me3修饰从常染色质入侵异染色质区域，从而维系端粒异染色质的沉默状态。综上，本研究揭示了一种全新的组蛋白串扰调控机制，并为响应细胞代谢状态的沉默异染色质与自噬动态调控提供了全新的理论视角。