Institute of Chemical Biology and Fundamental Medicine, Novosibirsk, Russia.
Biochimie. 2013 Jun;95(6):1208-15. doi: 10.1016/j.biochi.2013.01.007. Epub 2013 Jan 26.
Poly(ADP-ribosyl)ation is a posttranslational protein modification significant for genomic stability and cell survival in response to DNA damage. Poly(ADP-ribosyl)ation is catalyzed by poly(ADP-ribose)polymerases (PARPs). Among the 17 members of the PARP family, PARP-1 and PARP-2 are described as enzymes whose catalytic activity is stimulated by some types of DNA damages. Whereas the role of PARP-1 in response to DNA damage has been widely illustrated, the contribution of another DNA-dependent PARP, PARP-2, is less documented. To find out specific DNA targets of PARP-2 we evaluated by EMSA Kd values of PARP-2-DNA complexes for several DNA structures mimicking intermediates of different DNA metabolizing processes. In addition, we tested these DNA as activators of PARP-1 and PARP-2 in poly(ADP-ribose) synthesis. Like PARP-1, PARP-2 doesn't show correlation between activation efficiency and Kd values for DNA. PARP-2 displayed the highest affinity for flap-containing DNA, but was more efficiently activated by 5'-overhang DNA. Evaluating the influence of PARP-1 and PARP-2 on DNA repair synthesis catalyzed by DNA polymerase β revealed that both PARPs inhibit DNA polymerase β activity. However, unlike PARP-1, poly(ADP-ribosyl)ation of PARP-2 does not result in restoration of DNA synthesis efficiency. Similarly, both PARPs proteins inhibited FEN1 activity, but only activation of PARP-1, not PARP-2, could restore FEN1 activity, and only when PARP-2 was not present. Taken together, our data show that PARP-2 can directly regulate BER proteins but also can modulate the influence of PARP-1 on these BER proteins, by decreasing its poly(ADP-ribosyl)ation activity.
聚（ADP-核糖）化是一种翻译后蛋白质修饰，对于基因组稳定性和细胞存活响应 DNA 损伤至关重要。聚（ADP-核糖）化由聚（ADP-核糖）聚合酶（PARP）催化。在 PARP 家族的 17 个成员中，PARP-1 和 PARP-2 被描述为其催化活性受某些类型 DNA 损伤刺激的酶。虽然 PARP-1 在 DNA 损伤反应中的作用已被广泛阐明，但另一种 DNA 依赖性 PARP，PARP-2 的作用却记录较少。为了确定 PARP-2 的特定 DNA 靶标，我们通过 EMSA 评估了 PARP-2-DNA 复合物与几种 DNA 结构的 Kd 值，这些 DNA 结构模拟了不同 DNA 代谢过程的中间产物。此外，我们还测试了这些 DNA 作为 PARP-1 和 PARP-2 在聚（ADP-核糖）合成中的激活剂。与 PARP-1 一样，PARP-2 显示出与 DNA 的激活效率和 Kd 值之间没有相关性。PARP-2 对含 flap 的 DNA 显示出最高的亲和力，但对 5'-overhang DNA 的激活效率更高。评估 PARP-1 和 PARP-2 对 DNA 聚合酶 β 催化的 DNA 修复合成的影响表明，两种 PARP 都抑制 DNA 聚合酶 β 的活性。然而，与 PARP-1 不同，PARP-2 的聚（ADP-核糖）化不会导致 DNA 合成效率的恢复。同样，两种 PARP 蛋白都抑制了 FEN1 的活性，但只有 PARP-1 的激活，而不是 PARP-2 的激活，可以恢复 FEN1 的活性，并且只有当 PARP-2 不存在时才可以。总之，我们的数据表明，PARP-2 可以直接调节 BER 蛋白，也可以通过降低其聚（ADP-核糖）化活性来调节 PARP-1 对这些 BER 蛋白的影响。
