Formation of co-transcriptional R-loops underlies replication fork stalling upon head-on transcription-replication encounters. Here, we demonstrate that RAD51-dependent replication fork reversal induced by R-loops is followed by the restart of semiconservative DNA replication mediated by RECQ1 and RECQ5 helicases, MUS81/EME1 endonuclease, RAD52 strand-annealing factor, the DNA ligase IV (LIG4)/XRCC4 complex, and the non-catalytic subunit of DNA polymerase δ, POLD3. RECQ5 disrupts RAD51 filaments assembled on stalled forks after RECQ1-mediated reverse branch migration, preventing a new round of fork reversal and facilitating fork cleavage by MUS81/EME1. MUS81-dependent DNA breaks accumulate in cells lacking RAD52 or LIG4 upon induction of R-loop formation, suggesting that RAD52 acts in concert with LIG4/XRCC4 to catalyze fork religation, thereby mediating replication restart. The resumption of DNA synthesis after R-loop-associated fork stalling also requires active transcription, the restoration of which depends on MUS81, RAD52, LIG4, and the transcription elongation factor ELL. These findings provide mechanistic insights into transcription-replication conflict resolution.

中文翻译：

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在共转录R循环处停滞后，叉的分裂-宗教-循环和主动转录介导的复制重新开始。

共转录R环的形成是在正面转录-复制相遇时复制叉停滞的基础。在这里，我们证明了由R环引起的RAD51依赖的复制叉逆转由RECQ1和RECQ5解旋酶，MUS81 / EME1内切酶，RAD52链退火因子，DNA连接酶IV（LIG4）介导的半保守DNA复制的重启/ XRCC4复合物，以及DNA聚合酶δ的非催化亚基POLD3。在RECQ1介导的反向分支迁移后，RECQ5破坏了组装在停滞的货叉上的RAD51细丝，从而防止了新一轮的货叉反转，并促进了MUS81 / EME1对货叉的切割。诱导R环形成后，缺少RAD52或LIG4的细胞中积累了MUS81依赖的DNA断裂，这表明RAD52与LIG4 / XRCC4协同作用以催化叉子的连接，从而介导复制重启。R环相关叉停转后DNA合成的恢复也需要主动转录，其恢复取决于MUS81，RAD52，LIG4和转录延伸因子ELL。这些发现为转录复制冲突解决提供了机械的见解。