Leibniz Institute For Age Research-Fritz Lipmann Institute (FLI), Beutenberger strasse 11, 07745 Jena, Germany.
1] Leibniz Institute For Age Research-Fritz Lipmann Institute (FLI), Beutenberger strasse 11, 07745 Jena, Germany [2].
Nat Commun. 2013;4:2993. doi: 10.1038/ncomms3993.
Damaged replication forks activate poly(ADP-ribose) polymerase 1 (PARP1), which catalyses poly(ADP-ribose) (PAR) formation; however, how PARP1 or poly(ADP-ribosyl)ation is involved in the S-phase checkpoint is unknown. Here we show that PAR, supplied by PARP1, interacts with Chk1 via a novel PAR-binding regulatory (PbR) motif in Chk1, independent of ATR and its activity. iPOND studies reveal that Chk1 associates readily with the unperturbed replication fork and that PAR is required for efficient retention of Chk1 and phosphorylated Chk1 at the fork. A PbR mutation, which disrupts PAR binding, but not the interaction with its partners Claspin or BRCA1, impairs Chk1 and the S-phase checkpoint activation, and mirrors Chk1 knockdown-induced hypersensitivity to fork poisoning. We find that long chains, but not short chains, of PAR stimulate Chk1 kinase activity. Collectively, we disclose a previously unrecognized mechanism of the S-phase checkpoint by PAR metabolism that modulates Chk1 activity at the replication fork.
受损的复制叉激活多聚（ADP-核糖）聚合酶 1（PARP1），其催化多聚（ADP-核糖）（PAR）的形成；然而，PARP1 或聚（ADP-核糖基）化如何参与 S 期检查点尚不清楚。在这里，我们表明 PAR，由 PARP1 提供，通过 Chk1 中的新型 PAR 结合调节（PbR）基序与 Chk1 相互作用，独立于 ATR 及其活性。iPOND 研究表明 Chk1 很容易与未受干扰的复制叉结合，并且 PAR 对于有效保留 Chk1 和磷酸化 Chk1 在叉上是必需的。破坏 PAR 结合但不破坏其伴侣 Claspin 或 BRCA1 相互作用的 PbR 突变，会损害 Chk1 和 S 期检查点的激活，并模拟 Chk1 敲低诱导的叉子中毒敏感性。我们发现长链而不是短链 PAR 刺激 Chk1 激酶活性。总的来说，我们揭示了 PAR 代谢调节复制叉处 Chk1 活性的 S 期检查点的一种先前未被认识的机制。
