Idling by DNA polymerase δ maintains a ligatable nick during lagging-strand DNA replication
Idling by DNA polymerase δ maintains a ligatable nick during lagging-strand DNA replication
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DOI：
10.1101/gad.1252304
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发表时间：
2004-11-15
影响因子：
10.5
通讯作者：
Burgers, PM
中科院分区：
文献类型：
--
作者：
Garg, P;Stith, CM;Burgers, PM
在每个酵母细胞周期中，在滞后链DNA复制过程中产生了类似于100,000个划痕。在冈崎片段成熟期间的有效划痕处理需要DNA聚合酶6（POL Delta）和皮瓣核酸内切酶Fen1的协调作用。这种过程的不正调导致双链断裂和细胞杀伤力的积累。我们的研究突出了一种非常有效的机制，用于Okazaki碎片成熟，默认情况下，Pol Delta将遇到的任何下游RNA或DNA的2-3 nt置换。在存在Fen1的情况下，随之而来的是有效的镍翻译，从而释放了单寡核苷酸和小寡核苷酸的混合物。如果FEN1不存在或不发挥最佳功能，则POL 8通过其3'-5'-5'-exoniclease活性备份的能力（称为怠速的过程）将聚合酶保持在适合结扎的位置（如果是一个理想的位置） DNA-DNA Nick）或以Fen1的后续参与（如果是DNA-RNA刻痕）。与DNA聚合酶E是前链酶的假设一致，我们观察到这种酶没有闲置，也没有与Fen1的合作来创建可可鼠的痕迹。
During each yeast cell cycle, similar to100,000 nicks are generated during lagging-strand DNA replication. Efficient nick processing during Okazaki fragment maturation requires the coordinated action of DNA polymerase 6 (Pol delta) and the FLAP endonuclease FEN1. Misregulation of this process leads to the accumulation of double-stranded breaks and cell lethality. Our studies highlight a remarkably efficient mechanism for Okazaki fragment maturation in which Pol delta by default displaces 2-3 nt of any downstream RNA or DNA it encounters. In the presence of FEN1, efficient nick translation ensues, whereby a mixture of mono- and small oligonucleotides are released. If FEN1 is absent or not optimally functional, the ability of Pol 8 to back up via its 3'-5'-exonuclease activity, a process called idling, maintains the polymerase at a position that is ideal either for ligation (in case of a DNA-DNA nick) or for subsequent engagement by FEN1 (in case of a DNA-RNA nick). Consistent with the hypothesis that DNA polymerase e is the leading-strand enzyme, we observed no idling by this enzyme and no cooperation with FEN1 for creating a ligatable nick.