Division of Biochemistry, Department of Chemistry, University of Cincinnati, 301 Clifton Ct, Cincinnati, OH, 45221, USA.
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO, 63110, USA.
Biochem Biophys Res Commun. 2024 Aug 6;720:150101. doi: 10.1016/j.bbrc.2024.150101. Epub 2024 May 11.
Poly(ADP-ribose) polymerases (PARPs) are critical to regulating cellular activities, such as the response to DNA damage and cell death. PARPs catalyze a reversible post-translational modification (PTM) in the form of mono- or poly(ADP-ribosyl)ation. This type of modification is known to form a ubiquitin-ADP-ribose (Ub-ADPR) conjugate that depends on the actions of Deltex family of E3 ubiquitin ligases (DTXs). In particular, DTXs add ubiquitin to the 3'-OH of adenosine ribose' in ADP-ribose, which effectively sequesters ubiquitin and impedes ubiquitin-dependent signaling. Previous work demonstrates DTX function for ubiquitination of protein-free ADPR, mono-ADP-ribosylated peptides, and ADP-ribosylated nucleic acids. However, the dynamics of DTX-mediated ubiquitination of poly(ADP-ribosyl)ation remains to be defined. Here we show that the ADPR ubiquitination function is not found in other PAR-binding E3 ligases and is conserved across DTX family members. Importantly, DTXs specifically target poly(ADP-ribose) chains for ubiquitination that can be cleaved by PARG, the primary eraser of poly(ADP-ribose), leaving the adenosine-terminal ADPR unit conjugated to ubiquitin. Our collective results demonstrate the DTXs' specific ubiquitination of the adenosine terminus of poly(ADP-ribosyl)ation and suggest the unique Ub-ADPR conjugation process as a basis for PARP-DTX control of cellular activities.
聚（ADP-核糖）聚合酶（PARPs）对于调节细胞活动至关重要，例如对 DNA 损伤和细胞死亡的反应。PARPs 催化单聚或多聚（ADP-核糖基）化的可逆翻译后修饰（PTM）。这种类型的修饰已知形成依赖于 Deltex 家族 E3 泛素连接酶（DTXs）的泛素-ADP-核糖（Ub-ADPR）缀合物。特别是，DTXs 将泛素添加到 ADP-核糖的腺苷核糖'的 3'-OH 上，这有效地隔离了泛素并阻碍了泛素依赖性信号传导。以前的工作表明 DTX 可对无蛋白 ADPR、单聚 ADP-核糖基化肽和 ADP-核糖基化核酸进行泛素化。然而，DTX 介导的多聚（ADP-核糖基）化泛素化的动力学仍有待确定。在这里，我们表明 ADPR 泛素化功能不存在于其他 PAR 结合 E3 连接酶中，并且在 DTX 家族成员中是保守的。重要的是，DTXs 专门针对可被 PARG（多聚（ADP-核糖）的主要清除剂）切割的多聚（ADP-核糖）链进行泛素化，从而将腺苷末端的 ADPR 单元连接到泛素上。我们的综合结果表明 DTXs 对多聚（ADP-核糖基）化的腺苷末端具有特异性泛素化作用，并提出了独特的 Ub-ADPR 缀合过程作为 PARP-DTX 控制细胞活动的基础。
