Participation of DNA Polymerase ζ in Replication of Undamaged DNA in Saccharomyces cerevisiae
Participation of DNA Polymerase ζ in Replication of Undamaged DNA in Saccharomyces cerevisiae
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DOI：
10.1534/genetics.109.107482
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发表时间：
2010-01-01
期刊：
影响因子：
3.3
通讯作者：
Shcherbakova, Polina V.
中科院分区：
文献类型：
--
作者：
Northam, Matthew R.;Robinson, Heather A.;Shcherbakova, Polina V.
转录合成DNA聚合酶通过介导受损模板的复制而有助于DNA损伤耐受。由于这些酶的低保真度，病变旁路往往是致突变的。我们以前已经表明，在酿酒酵母中，如果正常的复制体由于复制基因的突变而有缺陷，则易错DNA聚合酶zeta（Pol zeta）对复制和诱变的贡献大大增强。在这里，我们提出的证据表明，这种缺陷复制体诱导的诱变（DRIM）的结果，从参与的Polzeta在复制未受损的DNA，而不是从诱变损伤旁路。首先，DRIM在由于核苷酸切除修复或碱基切除修复途径缺陷而具有高水平内源性DNA损伤的菌株中不升高。第二，DRIM保持不变时，内源性氧化DNA损伤的水平降低，通过使用厌氧生长条件。第三，对DRIM期间发生的突变谱的分析揭示了Pol zeta在体外复制未受损DNA期间观察到的特征性错误签名。这些结果扩展了大肠杆菌中的早期发现，表明Y家族DNA聚合酶可以促进未受损DNA的复制。我们还表明，野生型酵母细胞暴露于复制抑制剂羟基脲引起的Polzeta依赖性增加诱变。这表明DRIM代表了对复制障碍本身的响应，而不是对复制体组件中的特定缺陷的响应。
Translesion synthesis DNA polymerases contribute to DNA damage tolerance by mediating replication of damaged templates. Due to the low fidelity of these enzymes, lesion bypass is often mutagenic. We have previously shown that, in Saccharomyces cerevisiae, the contribution of the error-prone DNA polymerase zeta (Pol zeta) to replication and mutagenesis is greatly enhanced if the normal replisome is defective due to mutations in replication genes. Here we present evidence that this defective-replisome-induced mutagenesis (DRIM) results from the participation of Pol zeta in the copying of undamaged DNA rather than from mutagenic lesion bypass. First, DRIM is not elevated in strains that have a high level of endogenous DNA lesions due to defects in nucleotide excision repair or base excision repair pathways. Second, DRIM remains unchanged when the level of endogenous oxidative DNA damage is decreased by using anaerobic growth conditions. Third, analysis of the spectrum of mutations occurring during DRIM reveals the characteristic error signature seen during replication of undamaged DNA by Pol zeta in vitro. These results extend earlier findings in Escherichia coli indicating that Y-family DNA polymerases can contribute to the copying of undamaged DNA. We also show that exposure of wild-type yeast cells to the replication inhibitor hydroxyurea causes a Pol zeta-dependent increase in mutagenesis. This suggests that DRIM represents a response to replication impediment per se rather than to specific defects in the replisome components.