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Updated: Dec 13, 2025

Single-Molecule Fluorescence Visualization of DNA Polymerase Dynamics at G-Quadruplexes
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Timeless couples G-quadruplex detection with processing by DDX11 helicase during DNA replication.

Leticia K Lerner1, Sandro Holzer2, Mairi L Kilkenny2

  • 1MRC Laboratory of Molecular Biology, Cambridge, UK.

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|July 25, 2020
PubMed
Summary

Timeless protein helps DNA replication forks navigate G-quadruplex (G4) structures. This interaction with DDX11 helicase prevents DNA damage and maintains genetic stability.

Keywords:
DNA replicationG-quadruplexfork protection complexreplisometimeless

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Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • DNA secondary structures impede replication, threatening genetic integrity.
  • The replisome's response to these structures remains unclear.

Purpose of the Study:

  • Investigate how the replisome detects and resolves G-quadruplex (G4) DNA structures.
  • Elucidate the role of the Timeless protein in maintaining replication processivity through G4 sequences.

Main Methods:

  • Identified a novel G4 DNA-binding domain in the C-terminal region of Timeless.
  • Assessed Timeless function in G4 sequence replication, including its interaction with DDX11 helicase.
  • Analyzed epigenetic instability and DNA damage in Timeless and DDX11 deficient cells.

Main Results:

  • Timeless possesses a specific G4 DNA-binding domain crucial for processive replication.
  • This function is partially redundant with Timeless's PARP-binding domain and requires DDX11 activity.
  • Loss of both Timeless and DDX11 leads to epigenetic instability and DNA damage at G4 sites.

Conclusions:

  • Timeless acts as a sensor for replication-hindering G4 structures.
  • Timeless and DDX11 collaborate to ensure prompt G4 resolution, maintaining DNA synthesis and genome stability.