PDF(Pubmed)
Abstract：
DNA polymerase theta (Polθ)-mediated end-joining (TMEJ) repairs DNA double-strand breaks and confers resistance to genotoxic agents. How Polθ is regulated at the molecular level to exert TMEJ remains poorly characterized. We find that Polθ interacts with and is PARylated by PARP1 in a HPF1-independent manner. PARP1 recruits Polθ to the vicinity of DNA damage via PARylation dependent liquid demixing, however, PARylated Polθ cannot perform TMEJ due to its inability to bind DNA. PARG-mediated de-PARylation of Polθ reactivates its DNA binding and end-joining activities. Consistent with this, PARG is essential for TMEJ and the temporal recruitment of PARG to DNA damage corresponds with TMEJ activation and dissipation of PARP1 and PAR. In conclusion, we show a two-step spatiotemporal mechanism of TMEJ regulation. First, PARP1 PARylates Polθ and facilitates its recruitment to DNA damage sites in an inactivated state. PARG subsequently activates TMEJ by removing repressive PAR marks on Polθ.
摘要：
DNA聚合酶theta（Polθ）介导的末端连接（TMEJ）修复DNA双链断裂并赋予对遗传毒性剂的抗性。如何在分子水平上调节Polθ以发挥TMEJ仍然缺乏表征。我们发现Polθ与PARP1以HPFl非依赖性方式相互作用并被PARP1化。PARP1通过依赖PARylation的液体分层将Polθ募集到DNA损伤附近，然而,PARylatedPolθ由于无法结合DNA而无法进行TMEJ。PARG介导的Polθ去PARG激活其DNA结合和末端连接活性。与此一致，PARG对TMEJ至关重要，PARG对DNA损伤的时间募集与TMEJ激活和PARP1和PAR的消散相对应。总之,我们展示了TMEJ调控的两步时空机制。首先,PARP1PARylatePole并促进其在失活状态下募集到DNA损伤位点。PARG随后通过去除Pole上的抑制性PAR标记来激活TMEJ。
