The interplay of RNA:DNA hybrid structure and G-quadruplexes determines the outcome of R-loop-replisome collisions.
The interplay of RNA:DNA hybrid structure and G-quadruplexes determines the outcome of R-loop-replisome collisions.
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DOI：
10.7554/elife.72286
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发表时间：
2021-09-08
期刊：
影响因子：
7.7
通讯作者：
Remus D
中科院分区：
文献类型：
--
作者：
Kumar C;Batra S;Griffith JD;Remus D
R环是与转录诱导的复制应激相关的基因组不稳定性的主要来源。然而，R环如何固有地影响复制叉进展尚不清楚。在这里，我们的特点R-环复制体碰撞使用一个完全重建的真核DNA复制系统。我们发现，RNA：DNA杂交和G-四链体在同向和头上的R-环可以影响叉的进展，诱导叉失速，解偶联的前导链合成从复制体的进展，和新生的链间隙。RNase H1和Pif 1分别通过分解RNA：DNA杂合体和G-四链体来抑制复制缺陷。我们还确定了复制体的内在能力，以保持叉进展在某些R-环解旋RNA：DNA杂交，重引发的G-四链体的下游的前导链合成，或利用R-环转录物，以引发前导链重新启动在同向R-环复制体碰撞。总的来说，数据表明，R-环-复制体碰撞的结果是由R-环结构调节的，为区分有害R-环和无害R-环提供了机制基础。
R-loops are a major source of genome instability associated with transcription-induced replication stress. However, how R-loops inherently impact replication fork progression is not understood. Here, we characterize R-loop-replisome collisions using a fully reconstituted eukaryotic DNA replication system. We find that RNA:DNA hybrids and G-quadruplexes at both co-directional and head-on R-loops can impact fork progression by inducing fork stalling, uncoupling of leading strand synthesis from replisome progression, and nascent strand gaps. RNase H1 and Pif1 suppress replication defects by resolving RNA:DNA hybrids and G-quadruplexes, respectively. We also identify an intrinsic capacity of replisomes to maintain fork progression at certain R-loops by unwinding RNA:DNA hybrids, repriming leading strand synthesis downstream of G-quadruplexes, or utilizing R-loop transcripts to prime leading strand restart during co-directional R-loop-replisome collisions. Collectively, the data demonstrates that the outcome of R-loop-replisome collisions is modulated by R-loop structure, providing a mechanistic basis for the distinction of deleterious from non-deleterious R-loops.