Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
Department of Biomedical Sciences, Chung Shan Medical University, Taichung 402, Taiwan.
Genes (Basel). 2019 Jul 30;10(8):577. doi: 10.3390/genes10080577.
O-acetyl-ADP-ribose (AAR) is a metabolic small molecule relevant in epigenetics that is generated by NAD-dependent histone deacetylases, such as Sir2. The formation of silent heterochromatin in yeast requires histone deacetylation by Sir2, structural rearrangement of SIR complexes, spreading of SIR complexes along the chromatin, and additional maturation processing. AAR affects the interactions of the SIR-nucleosome in vitro and enhances the chromatin epigenetic silencing effect in vivo. In this study, using isothermal titration calorimetry (ITC) and dot blotting methods, we showed the direct interaction of AAR with Sir3. Furthermore, through chromatin immunoprecipitation (ChIP)-on-chip and chromatin affinity purification (ChAP)-on chip assays, we discovered that AAR is capable of increasing the extended spreading of Sir3 along telomeres, but not Sir2. In addition, the findings of a quantitative real-time polymerase chain reaction (qRT-PCR) and examinations of an in vitro assembly system of SIR-nucleosome heterochromatin filament were consistent with these results. This study provides evidence indicating another important effect of AAR in vivo. AAR may play a specific modulating role in the formation of silent SIR-nucleosome heterochromatin in yeast.
O-乙酰基-ADP-核糖（AAR）是一种与表观遗传学相关的代谢性小分子，由 NAD 依赖性组蛋白去乙酰化酶（如 Sir2）产生。酵母中沉默异染色质的形成需要 Sir2 介导的组蛋白去乙酰化、SIR 复合物的结构重排、SIR 复合物沿着染色质的扩散以及额外的成熟加工。AAR 影响 SIR-核小体在体外的相互作用，并增强体内的染色质表观遗传沉默效应。在这项研究中，我们使用等温滴定量热法（ITC）和点印迹法表明 AAR 与 Sir3 的直接相互作用。此外，通过染色质免疫沉淀（ChIP）-芯片和染色质亲和纯化（ChAP）-芯片分析，我们发现 AAR 能够增加 Sir3 在端粒上的扩展扩散，但不能增加 Sir2。此外，定量实时聚合酶链反应（qRT-PCR）的结果和 SIR-核小体异染色质丝体外组装系统的检测结果与这些结果一致。这项研究提供了证据表明 AAR 在体内具有另一个重要作用。AAR 可能在酵母中沉默 SIR-核小体异染色质的形成中发挥特定的调节作用。
