UvrD Participation in Nucleotide Excision Repair Is Required for the Recovery of DNA Synthesis following UV-Induced Damage in Escherichia coli.
UvrD Participation in Nucleotide Excision Repair Is Required for the Recovery of DNA Synthesis following UV-Induced Damage in Escherichia coli.
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DOI：
10.1155/2012/271453
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发表时间：
2012
影响因子：
2.3
通讯作者：
Courcelle J
中科院分区：
文献类型：
--
作者：
Newton KN;Courcelle CT;Courcelle J
UvrD是一种DNA解旋酶，参与核苷酸切除修复和几个复制相关过程，包括甲基定向错配修复和重组。UvrD能够在体外取代合成分叉DNA结构上的寡核苷酸，并且在缺乏Rep（一种与处理复制分叉相关的解旋酶）的情况下对生存能力至关重要。这些观察结果导致其他人提出，UvrD可能会促进分叉回归，并在捕获后促进复制分叉的重置。然而，UvrD在体内复制分叉处的分子活性尚未被直接检测。在这项研究中，我们描述了UvrD在处理和恢复被紫外线诱导的DNA损伤后的复制分叉中的作用。我们发现UvrD是DNA合成恢复所必需的。然而，在缺乏UvrD的情况下，在受阻叉处的新生DNA的位移和部分降解正常发生。此外，损伤诱导的复制中间体在uvrD突变体中持续存在并积累，其方式与在其他核苷酸切除修复突变体中观察到的相似。这些数据表明，在DNA损伤阻滞后，UvrD在体内不需要催化叉回归，并表明UvrD突变体在紫外线诱导的阻滞后恢复DNA合成的失败与其在核苷酸切除修复中的作用有关。
UvrD is a DNA helicase that participates in nucleotide excision repair and several replication-associated processes, including methyl-directed mismatch repair and recombination. UvrD is capable of displacing oligonucleotides from synthetic forked DNA structures in vitro and is essential for viability in the absence of Rep, a helicase associated with processing replication forks. These observations have led others to propose that UvrD may promote fork regression and facilitate resetting of the replication fork following arrest. However, the molecular activity of UvrD at replication forks in vivo has not been directly examined. In this study, we characterized the role UvrD has in processing and restoring replication forks following arrest by UV-induced DNA damage. We show that UvrD is required for DNA synthesis to recover. However, in the absence of UvrD, the displacement and partial degradation of the nascent DNA at the arrested fork occur normally. In addition, damage-induced replication intermediates persist and accumulate in uvrD mutants in a manner that is similar to that observed in other nucleotide excision repair mutants. These data indicate that, following arrest by DNA damage, UvrD is not required to catalyze fork regression in vivo and suggest that the failure of uvrD mutants to restore DNA synthesis following UV-induced arrest relates to its role in nucleotide excision repair.