Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation
Rad51 recombinase prevents Mre11 nuclease-dependent degradation and excessive PrimPol-mediated elongation of nascent DNA after UV irradiation
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DOI：
10.1073/pnas.1508543112
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发表时间：
2015-12-01
影响因子：
11.1
通讯作者：
Gottifredi, Vanesa
中科院分区：
文献类型：
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作者：
Belen Vallerga, Maria;Mansilla, Sabrina F.;Gottifredi, Vanesa
在紫外线照射后，DNA聚合酶专门用于翻译DNA合成（TLS），帮助DNA复制。然而，目前尚不清楚是否其他机制也促进了紫外线损伤DNA的延伸。我们想知道Rad51重组酶（Rad51），一个护送复制叉的因子，是否有助于跨紫外线损伤的复制。我们发现，在紫外线照射后，Rad51的缺失损害了s期的进展，增加了细胞的死亡。有趣的是，Rad51和TLS聚合酶pol eta以不同的方式调节新生DNA的延伸，这表明紫外线照射后的DNA延伸并不完全依赖于TLS事件。特别是，Rad51保护紫外线照射前立即合成的DNA免受降解，并避免紫外线照射后新生DNA的过度伸长。在缺乏rad51的样品中，DNA的降解仅限于紫外线照射后的头几分钟，并且需要双链断裂修复核酸酶（Mre11）的外切酶活性。Rad51敲低后新生DNA延伸的持续失调需要Mre11，而不需要Mre11的外切酶活性和PrimPol（一种具有引物酶活性的DNA聚合酶）。通过展示Rad51对新生DNA合成的重要贡献，我们的研究结果揭示了紫外线损伤模板中DNA延伸调节的意想不到的复杂性。
After UV irradiation, DNA polymerases specialized in translesion DNA synthesis (TLS) aid DNA replication. However, it is unclear whether other mechanisms also facilitate the elongation of UV-damaged DNA. We wondered if Rad51 recombinase (Rad51), a factor that escorts replication forks, aids replication across UV lesions. We found that depletion of Rad51 impairs S-phase progression and increases cell death after UV irradiation. Interestingly, Rad51 and the TLS polymerase pol eta modulate the elongation of nascent DNA in different ways, suggesting that DNA elongation after UV irradiation does not exclusively rely on TLS events. In particular, Rad51 protects the DNA synthesized immediately before UV irradiation from degradation and avoids excessive elongation of nascent DNA after UV irradiation. In Rad51-depleted samples, the degradation of DNA was limited to the first minutes after UV irradiation and required the exonuclease activity of the double strand break repair nuclease (Mre11). The persistent dysregulation of nascent DNA elongation after Rad51 knockdown required Mre11, but not its exonuclease activity, and PrimPol, a DNA polymerase with primase activity. By showing a crucial contribution of Rad51 to the synthesis of nascent DNA, our results reveal an unanticipated complexity in the regulation of DNA elongation across UV-damaged templates.