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Interplay among replicative and specialized DNA polymerases determines failure or success of translesion synthesis

Shingo Fujii1, Robert P Fuchs1

  • 1Genome Instability and Carcinogenesis, CNRS FRE2931, Campus J. Aiguier, Marseille, France.

Journal of Molecular Biology
|August 21, 2007
PubMed

Insights

Specialized DNA polymerases (Pol II and Pol V) bypass DNA lesions through distinct pathways. The beta-clamp is crucial for Pol II processivity, ensuring replication fork progression and preventing degradation.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Living cells utilize specialized DNA polymerases to repair diverse genomic DNA lesions.
  • The mechanism by which these polymerases access replication intermediates near DNA lesions remains unclear.

Purpose of the Study:

  • To investigate the interplay between replicative and specialized DNA polymerases in bypassing DNA lesions.
  • To elucidate the roles of specific DNA polymerases (Pol II and Pol V) and accessory factors in translesion synthesis (TLS).

Main Methods:

  • Development of a model system with a single N-2-acetylaminofluorene guanine adduct to study lesion bypass.
  • Reconstitution of TLS pathways using purified DNA polymerases (Pol III, Pol II, Pol V) and accessory factors.
  • Analysis of replication intermediates and molecular signatures produced by different bypass pathways.

Main Results:

  • Identified distinct replication intermediates preferentially utilized by Pol II and Pol V.
  • Demonstrated the critical role of the beta-clamp in enhancing Pol II processivity for a -2 frameshift intermediate.
  • Showed that replicative polymerase proofreading prevents Pol II-mediated -1 frameshift products.

Conclusions:

  • Translesion synthesis pathway success is determined by the complex interactions among DNA polymerases and accessory factors.
  • The beta-clamp's role in Pol II processivity is essential for efficient replication fork progression past lesions.
  • Replicative polymerase proofreading acts as a safeguard against error-prone TLS events.

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