Involvement of G-quadruplex regions in mammalian replication origin activity

authors

  • Prorok Paulina
  • Artufel Marie
  • Aze Antoine
  • Coulombe Philippe
  • Peiffer Isabelle
  • Lacroix Laurent
  • Guédin Aurore
  • Mergny Jean-Louis
  • Damaschke Julia
  • Schepers Aloys
  • Ballester Benoit
  • Méchali Marcel

keywords

  • Molecular biology
  • Chromatin
  • Origin selection

document type

ART

abstract

Genome-wide studies of DNA replication origins revealed that origins preferentially associate with an Origin G-rich Repeated Element (OGRE), potentially forming G-quadruplexes (G4). Here, we functionally address their requirements for DNA replication initiation in a series of independent approaches. Deletion of the OGRE/G4 sequence strongly decreased the corresponding origin activity. Conversely, the insertion of an OGRE/G4 element created a new replication origin. This element also promoted replication of episomal EBV vectors lacking the viral origin, but not if the OGRE/G4 sequence was deleted. A potent G4 ligand, PhenDC3, stabilized G4s but did not alter the global origin activity. However, a set of new, G4-associated origins was created, whereas suppressed origins were largely G4-free. In vitro Xenopus laevis replication systems showed that OGRE/G4 sequences are involved in the activation of DNA replication, but not in the pre-replication complex formation. Altogether, these results converge to the functional importance of OGRE/G4 elements in DNA replication initiation.

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