重复 DNA 内复制停滞和恢复的机制。
The mechanism of replication stalling and recovery within repetitive DNA.
机构信息
Genome Replication lab, Division of Cancer Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London, SW3 6JB, UK.
出版信息
Nat Commun. 2022 Jul 19;13(1):3953. doi: 10.1038/s41467-022-31657-x.
Accurate chromosomal DNA replication is essential to maintain genomic stability. Genetic evidence suggests that certain repetitive sequences impair replication, yet the underlying mechanism is poorly defined. Replication could be directly inhibited by the DNA template or indirectly, for example by DNA-bound proteins. Here, we reconstitute replication of mono-, di- and trinucleotide repeats in vitro using eukaryotic replisomes assembled from purified proteins. We find that structure-prone repeats are sufficient to impair replication. Whilst template unwinding is unaffected, leading strand synthesis is inhibited, leading to fork uncoupling. Synthesis through hairpin-forming repeats is rescued by replisome-intrinsic mechanisms, whereas synthesis of quadruplex-forming repeats requires an extrinsic accessory helicase. DNA-induced fork stalling is mechanistically similar to that induced by leading strand DNA lesions, highlighting structure-prone repeats as an important potential source of replication stress. Thus, we propose that our understanding of the cellular response to replication stress may also be applied to DNA-induced replication stalling.
准确的染色体 DNA 复制对于维持基因组稳定性至关重要。遗传证据表明,某些重复序列会损害复制,但其中的潜在机制尚未明确。复制可能会被 DNA 模板直接抑制,也可能通过 DNA 结合蛋白间接抑制。在此,我们使用从纯化蛋白组装而成的真核复制体在体外重新构建单核苷酸、二核苷酸和三核苷酸重复序列的复制。我们发现,结构倾向重复序列足以损害复制。尽管模板解旋不受影响,但领头链合成受到抑制,导致叉解偶联。发夹形成重复序列的合成可通过复制体内在机制得到挽救,而四链体形成重复序列的合成则需要外在辅助解旋酶。DNA 诱导的叉停顿在机制上与引发链 DNA 损伤诱导的叉停顿相似,突出了结构倾向重复序列作为复制压力的重要潜在来源。因此,我们提出,我们对细胞对复制压力的反应的理解也可能适用于 DNA 诱导的复制停顿。
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