Department of Physics and Astronomy, Institute of Applied Physics, National Center of Creative Research Initiatives, Seoul National University, Seoul 08826, Republic of Korea.
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
Cell Rep. 2018 May 8;23(6):1831-1839. doi: 10.1016/j.celrep.2018.04.029.
Replication fork reversal is one of the major pathways for reactivating stalled DNA replication. Many enzymes with replication fork reversal activity have DNA-unwinding activity as well, but none of the fork reversal enzymes in the SWI/SNF family shows a separate DNA-unwinding activity, raising the question of how they initiate the remodeling process. Here, we found ATP binding to Rad5 induces the unwinding of the leading arm of the replication fork and proximally positions the leading and lagging arms. This facilitates the spontaneous remodeling of the replication fork into a four-way junction. Once the four-way junction is formed, Rad5 migrates the four-way junction at a speed of 7.1 ± 0.14 nt/s. The 3' end anchoring of the leading arm by Rad5's HIRAN domain is critical for both branch migration and the recovery of the three-way junction, but not for the structural transition to the four-way junction.
复制叉反转是重新激活停滞 DNA 复制的主要途径之一。许多具有复制叉反转活性的酶也具有 DNA 解旋活性，但 SWI/SNF 家族中的任何一种叉反转酶都没有独立的 DNA 解旋活性，这就提出了一个问题，即它们如何启动重塑过程。在这里，我们发现 ATP 结合 Rad5 诱导复制叉前导臂的解旋，并将前导链和滞后链定位在附近。这有助于复制叉自发地重塑为四叉结。一旦形成四叉结，Rad5 以 7.1±0.14nt/s 的速度迁移四叉结。Rad5 的 HIRAN 结构域对前导臂 3' 端的锚定对于分支迁移和三链结的恢复都是至关重要的，但对于结构向四叉结的转变则不是必需的。
