The Rockefeller University, Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10021, USA.
Science. 2010 Jan 29;327(5965):590-2. doi: 10.1126/science.1179595.
In vivo studies suggest that replication forks are arrested by encounters with head-on transcription complexes. Yet, the fate of the replisome and RNA polymerase (RNAP) after a head-on collision is unknown. We found that the Escherichia coli replisome stalls upon collision with a head-on transcription complex, but instead of collapsing, the replication fork remains highly stable and eventually resumes elongation after displacing the RNAP from DNA. We also found that the transcription-repair coupling factor Mfd promotes direct restart of the fork after the collision by facilitating displacement of the RNAP. These findings demonstrate the intrinsic stability of the replication apparatus and a previously unknown role for the transcription-coupled repair pathway in promoting replication past a RNAP block.
体内研究表明，复制叉会因与迎面而来的转录复合物相遇而停滞。然而，迎面碰撞后复制体和 RNA 聚合酶 (RNAP) 的命运尚不清楚。我们发现，大肠杆菌复制体在与迎面而来的转录复合物碰撞时会停滞，但复制叉不会崩溃，而是保持高度稳定，并在将 RNAP 从 DNA 上置换后最终恢复延伸。我们还发现，转录修复偶联因子 Mfd 通过促进 RNAP 的置换，促进碰撞后叉的直接重新启动。这些发现表明复制装置具有内在的稳定性，以及转录偶联修复途径在促进 RNA 聚合酶阻断后的复制方面的未知作用。
