Institut Jacques Monod, CNRS UMR7592 Université Paris Diderot Equipe Labellisée Ligue contre le cancer, Paris, France.
EMBO J. 2014 Apr 1;33(7):732-46. doi: 10.1002/embj.201387506. Epub 2014 Feb 12.
DNA replication ensures the accurate duplication of the genome at each cell cycle. It begins at specific sites called replication origins. Genome-wide studies in vertebrates have recently identified a consensus G-rich motif potentially able to form G-quadruplexes (G4) in most replication origins. However, there is no experimental evidence to demonstrate that G4 are actually required for replication initiation. We show here, with two model origins, that G4 motifs are required for replication initiation. Two G4 motifs cooperate in one of our model origins. The other contains only one critical G4, and its orientation determines the precise position of the replication start site. Point mutations affecting the stability of this G4 in vitro also impair origin function. Finally, this G4 is not sufficient for origin activity and must cooperate with a 200-bp cis-regulatory element. In conclusion, our study strongly supports the predicted essential role of G4 in replication initiation.
DNA 复制确保了基因组在每个细胞周期中的准确复制。它从称为复制起点的特定位置开始。最近在脊椎动物中的全基因组研究鉴定了一种潜在的共识 G 丰富基序，该基序能够在大多数复制起点形成 G-四链体 (G4)。然而，目前还没有实验证据表明 G4 实际上是复制起始所必需的。我们在这里使用两个模型起点表明，G4 基序是复制起始所必需的。两个 G4 基序在我们的一个模型起点中合作。另一个只包含一个关键的 G4，其方向决定了复制起始位点的精确位置。影响体外该 G4 稳定性的点突变也会损害起始功能。最后，这个 G4 不足以使起点发挥活性，必须与 200bp 的顺式调控元件合作。总之，我们的研究强烈支持 G4 在复制起始中的预测的重要作用。
