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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Interplay between replication and recombination in Escherichia coli: Impact of the alternative DNA polymerases
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Interplay between replication and recombination in Escherichia coli: Impact of the alternative DNA polymerases

机译：大肠杆菌中复制和重组之间的相互作用：替代DNA聚合酶的影响

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摘要

Homologous recombination (HR) and translesion synthesis (TLS) are two pathways involved in the tolerance of lesions that block the replicative DNA polymerase. However, whereas TLS is frequently error-prone and, therefore, can be deleterious, HR is generally error-free. Furthermore, because the recombination enzymes and alternative DNA polymerases that perform TLS may use the same substrate, their coordination might be important to assure cell fitness and survival. This study aimed to determine whether and how these pathways are coordinated in Escherichia coli cells by using conjugational replication and recombination as a model system. The role of the three alternative DNA polymerases that are regulated by the SOS system was tested in DNA polymerase Ⅲ holoenzyme-proficient and -deficient mutants. When PolⅢ is inactive, the alternative DNA polymerases copy DNA in the following order: PolⅡ, PolⅣ, and PolⅤ. The observed hierarchy corresponds to the selective constraints imposed on the genes coding for alternative DNA polymerases observed in natural populations of E. coli, suggesting that this hierarchy depends on the frequency of specific damages encountered during the evolutionary history of E. coli. We also found that DNA replication and HR are in competition and that they can precede each other. Our results suggest that there is probably not an active choice of which pathway to use, but, rather, the nature and concentration of lesions that lead to formation of ssDNA and the level of SOS induction that they engender might determine the outcome of the competition between HR and alternative DNA polymerases.
机译：同源重组（HR）和跨病变合成（TLS）是参与阻止复制DNA聚合酶的病变耐受性的两条途径。但是，尽管TLS经常容易出错，因此可能有害，但HR通常没有错误。此外，由于执行TLS的重组酶和其他DNA聚合酶可能使用相同的底物，因此它们的协调对于确保细胞适应性和存活可能很重要。这项研究旨在通过使用共轭复制和重组作为模型系统来确定在大肠杆菌细胞中是否以及如何协调这些途径。在DNA聚合酶Ⅲ全酶高效和缺陷突变体中检验了SOS系统调控的三种替代DNA聚合酶的作用。当PolⅢ失活时，其他DNA聚合酶按以下顺序复制DNA：PolⅡ，PolⅣ和PolⅤ。观察到的等级对应于对在大肠杆菌自然种群中观察到的替代性DNA聚合酶编码的基因施加的选择性限制，这表明该等级取决于在大肠杆菌进化史中遇到的特定损伤的频率。我们还发现，DNA复制和HR竞争激烈，它们可以相互促进。我们的结果表明，可能没有主动选择使用哪种途径，而是导致ssDNA形成的病变的性质和集中程度以及它们引起的SOS诱导水平可能决定了两者之间竞争的结果。 HR和其他DNA聚合酶。

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