Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
Nucleic Acids Res. 2018 Dec 14;46(22):12154-12165. doi: 10.1093/nar/gky927.
Human ARTD2 (or PARP2) is an ADP-ribosyltransferase, which is catalytically activated by binding to damaged DNA. ARTD2 subsequently ADP-ribosylates itself and other proteins, initiating a cascade of events leading to DNA repair. In contrast to ARTD1, the founding member of the enzyme family, ARTD2 does not have specialized zinc-fingers for detecting DNA damage. The domain organization of ARTD2 includes disordered N-terminus, WGR and catalytic domains. However, the N-terminus of ARTD2 is not strictly required for the DNA dependent activity. While it is known that ARTD2 requires the WGR domain for efficient DNA binding and subsequent catalytic activation, the mechanism of DNA damage detection and subsequent catalytic activation are not completely understood. Here, we report crystal structures of ARTD2 WGR domain bound to double-strand break mimicking DNA oligonucleotides. Notably, the crystal structures revealed DNA binding mode of ARTD2 involving DNA end to end interaction. Structures demonstrate how ARTD2 recognizes nicked DNA, how it interacts with the 5'-phosphate group, and how it can mediate joining of DNA ends in vitro. Extensive mutagenesis of the ARTD2-DNA interface combined with activity, binding, and stoichiometry measurements demonstrate that the WGR domain is the key for DNA break detection.
人类 ARTD2（或 PARP2）是一种 ADP-ribosyltransferase，它通过与受损 DNA 结合而被催化激活。ARTD2 随后会自身 ADP-ribosylates 和其他蛋白质，引发一系列事件，导致 DNA 修复。与酶家族的创始成员 ARTD1 不同，ARTD2 没有专门的锌指来检测 DNA 损伤。ARTD2 的结构域组织包括无序的 N 端、WGR 和催化结构域。然而，ARTD2 的 N 端对于 DNA 依赖性活性并非严格必需。虽然已知 ARTD2 需要 WGR 结构域来有效结合 DNA 和随后的催化激活，但 DNA 损伤检测和随后的催化激活的机制尚不完全清楚。在这里，我们报告了 ARTD2 WGR 结构域与双链断裂模拟 DNA 寡核苷酸结合的晶体结构。值得注意的是，晶体结构揭示了 ARTD2 的 DNA 结合模式，涉及 DNA 端到端相互作用。这些结构展示了 ARTD2 如何识别带有缺口的 DNA，如何与 5'-磷酸基团相互作用，以及如何在体外介导 DNA 末端的连接。对 ARTD2-DNA 界面的广泛突变结合活性、结合和计量学测量表明，WGR 结构域是 DNA 断裂检测的关键。
