Katou Yuki, Kanoh Yutaka, Bando Masashige, Noguchi Hideki, Tanaka Hirokazu, Ashikari Toshihiko, Sugimoto Katsunori, Shirahige Katsuhiko
Genome Structure and Function Team, Human Genome Research Group, RIKEN Genomic Science Center, 1-7-22 Suehiro-cho, Japan.
Nature. 2003 Aug 28;424(6952):1078-83. doi: 10.1038/nature01900.
The checkpoint regulatory mechanism has an important role in maintaining the integrity of the genome. This is particularly important in S phase of the cell cycle, when genomic DNA is most susceptible to various environmental hazards. When chemical agents damage DNA, activation of checkpoint signalling pathways results in a temporary cessation of DNA replication. A replication-pausing complex is believed to be created at the arrested forks to activate further checkpoint cascades, leading to repair of the damaged DNA. Thus, checkpoint factors are thought to act not only to arrest replication but also to maintain a stable replication complex at replication forks. However, the molecular mechanism coupling checkpoint regulation and replication arrest is unknown. Here we demonstrate that the checkpoint regulatory proteins Tof1 and Mrc1 interact directly with the DNA replication machinery in Saccharomyces cerevisiae. When hydroxyurea blocks chromosomal replication, this assembly forms a stable pausing structure that serves to anchor subsequent DNA repair events.
检查点调控机制在维持基因组完整性方面发挥着重要作用。这在细胞周期的S期尤为重要，此时基因组DNA最易受到各种环境危害。当化学试剂损伤DNA时，检查点信号通路的激活会导致DNA复制暂时停止。据信，在停滞的复制叉处会形成一个复制暂停复合物，以激活进一步的检查点级联反应，从而修复受损的DNA。因此，检查点因子不仅被认为可阻止复制，还能在复制叉处维持稳定的复制复合物。然而，将检查点调控与复制停滞联系起来的分子机制尚不清楚。在这里，我们证明了检查点调控蛋白Tof1和Mrc1在酿酒酵母中直接与DNA复制机制相互作用。当羟基脲阻断染色体复制时，这种组装会形成一个稳定的暂停结构，用于锚定随后的DNA修复事件。
