The Balance between Recombination Enzymes and Accessory Replicative Helicases in Facilitating Genome Duplication.
The Balance between Recombination Enzymes and Accessory Replicative Helicases in Facilitating Genome Duplication.
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DOI：
10.3390/genes7080042
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发表时间：
2016-07-29
期刊：
影响因子：
3.5
通讯作者：
McGlynn P
中科院分区：
文献类型：
--
作者：
Syeda AH;Atkinson J;Lloyd RG;McGlynn P
辅助复制解旋酶帮助初级复制解旋酶复制蛋白质结合的DNA，尤其是转录的DNA。通过链交换促进DNA损伤的修复，以及加工阻断的叉DNA以产生复制体可以重新加载到其上的结构，复制酶也有助于基因组复制。在细菌和低等真核生物中，辅助解旋酶和重组酶之间存在显著的相互作用，但这些复制修复系统如何相互作用以确保有效的基因组复制仍不清楚。在这里，我们证明了缺乏链交换蛋白RecA的大肠杆菌细胞的DNA含量缺陷主要是由复制和转录之间的冲突驱动的，因为在细胞缺乏辅助解旋酶Rep.然而，与Rep相反，无论是RecA还是RecBCD，将RecA加载到双链DNA末端的解旋酶/核酸外切酶，对于维持快速染色体复制是重要的。此外，RecA和RecBCD一起可以维持生存能力，在辅助复制解旋酶的情况下，但只有当复制的转录障碍被抑制的RNA聚合酶突变。我们的数据表明，最小化复制体暂停辅助解旋酶有一个更显着的影响，成功完成染色体复制比重组定向叉修复。
Accessory replicative helicases aid the primary replicative helicase in duplicating protein-bound DNA, especially transcribed DNA. Recombination enzymes also aid genome duplication by facilitating the repair of DNA lesions via strand exchange and also processing of blocked fork DNA to generate structures onto which the replisome can be reloaded. There is significant interplay between accessory helicases and recombination enzymes in both bacteria and lower eukaryotes but how these replication repair systems interact to ensure efficient genome duplication remains unclear. Here, we demonstrate that the DNA content defects of Escherichia coli cells lacking the strand exchange protein RecA are driven primarily by conflicts between replication and transcription, as is the case in cells lacking the accessory helicase Rep. However, in contrast to Rep, neither RecA nor RecBCD, the helicase/exonuclease that loads RecA onto dsDNA ends, is important for maintaining rapid chromosome duplication. Furthermore, RecA and RecBCD together can sustain viability in the absence of accessory replicative helicases but only when transcriptional barriers to replication are suppressed by an RNA polymerase mutation. Our data indicate that the minimisation of replisome pausing by accessory helicases has a more significant impact on successful completion of chromosome duplication than recombination-directed fork repair.