Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
Genome Integrity & Structural Biology Laboratory, NIH/NIEHS, DHHS, Research Triangle Park, NC 27709, USA.
Mol Cell. 2019 Nov 7;76(3):371-381.e4. doi: 10.1016/j.molcel.2019.07.033. Epub 2019 Sep 5.
Break-induced replication (BIR) is a pathway of homology-directed repair that repairs one-ended DNA breaks, such as those formed at broken replication forks or uncapped telomeres. In contrast to conventional S phase DNA synthesis, BIR proceeds by a migrating D-loop and results in conservative synthesis of the nascent strands. DNA polymerase delta (Pol δ) initiates BIR; however, it is not known whether synthesis of the invading strand switches to a different polymerase or how the complementary strand is synthesized. By using alleles of the replicative DNA polymerases that are permissive for ribonucleotide incorporation, thus generating a signature of their action in the genome that can be identified by hydrolytic end sequencing, we show that Pol δ replicates both the invading and the complementary strand during BIR. In support of this conclusion, we show that depletion of Pol δ from cells reduces BIR, whereas depletion of Pol ε has no effect.
断裂诱导复制（BIR）是一种同源定向修复途径，可修复单端 DNA 断裂，例如在复制叉断裂或无端粒帽处形成的断裂。与传统的 S 期 DNA 合成不同，BIR 通过迁移的 D 环进行，导致新生链的保守合成。DNA 聚合酶 δ（Pol δ）启动 BIR；然而，尚不清楚入侵链的合成是否切换到另一种聚合酶，以及互补链是如何合成的。通过使用允许核苷酸掺入的复制 DNA 聚合酶的等位基因，从而在基因组中产生其作用的特征，该特征可以通过水解末端测序来识别，我们表明 Pol δ 在 BIR 过程中复制入侵链和互补链。为了支持这一结论，我们表明从细胞中耗尽 Pol δ 会减少 BIR，而耗尽 Pol ε 则没有影响。
