Fork Cleavage-Religation Cycle and Active Transcription Mediate Replication Restart after Fork Stalling at Co-transcriptional R-Loops
Fork Cleavage-Religation Cycle and Active Transcription Mediate Replication Restart after Fork Stalling at Co-transcriptional R-Loops
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DOI：
10.1016/j.molcel.2019.10.026
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发表时间：
2020-02-06
期刊：
影响因子：
16
通讯作者：
Janscak, Pavel
中科院分区：
文献类型：
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作者：
Chappidi, Nagaraja;Nascakova, Zuzana;Janscak, Pavel
共转录R环的形成是复制叉在迎面转录-复制相遇时停滞的基础。在这里，我们证明了由R环诱导的RAD 51依赖性复制叉逆转之后是由RECQ 1和RECQ 5解旋酶，MUS 81/EME 1核酸内切酶，RAD 52链退火因子，DNA连接酶IV（LIG 4）/XRCC 4复合物和DNA聚合酶δ的非催化亚基POLD 3介导的保守性DNA复制的重新启动。在RECQ 1介导的反向分支迁移后，RECQ 5破坏组装在停滞叉上的RAD 51细丝，防止新一轮叉逆转并促进MUS 81/EME 1的叉切割。在诱导R环形成时，MUS 81依赖性DNA断裂在缺乏RAD 52或LIG 4的细胞中积累，表明RAD 52与LIG 4/XRCC 4协同作用以催化叉再连接，从而介导复制重启。R环相关叉停滞后DNA合成的恢复也需要主动转录，其恢复依赖于MUS 81、RAD 52、LIG 4和转录延伸因子ELL。这些发现提供了机制的见解转录复制冲突的解决。
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 delta, 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.