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Interstrand cross-links arising from strand breaks at true abasic sites in duplex DNA

Zhiyu Yang1, Nathan E Price2, Kevin M Johnson1

  • 1Department of Chemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211, USA.

Nucleic Acids Research
|May 23, 2017
PubMed

Insights

DNA damage from abasic sites can form interstrand cross-links (ICLs) adjacent to strand breaks. These ICLs block DNA replication, highlighting their potential to disrupt critical DNA transactions.

Area of Science:

  • DNA repair and replication
  • Molecular biology
  • Biochemistry

Background:

  • Interstrand cross-links (ICLs) are DNA lesions implicated in aging, neurodegeneration, and cancer.
  • Abasic (Ap) sites are common DNA lesions prone to strand cleavage, forming a 3' dideoxyribose phosphate (3'ddR5p) remnant.
  • This cleavage process generates an electrophilic α,β-unsaturated aldehyde residue within the nicked DNA duplex.

Purpose of the Study:

  • To investigate the formation of complex DNA lesions resulting from abasic site cleavage.
  • To determine if these lesions can form interstrand cross-links.
  • To assess the impact of these cross-links on DNA replication.

Main Methods:

  • Spermine-catalyzed cleavage of abasic sites in duplex DNA.
  • Liquid chromatography-tandem mass spectrometry (LC-MS/MS) for lesion identification and characterization.
  • DNA replication assays using ϕ29 DNA polymerase.

Main Results:

  • 3'ddR5p derivatives from spermine-catalyzed cleavage at Ap sites can form ICLs with opposing adenine residues.
  • These complex lesions create an interstrand cross-link adjacent to a strand break.
  • The generated ICLs effectively block DNA replication by the processive ϕ29 DNA polymerase.

Conclusions:

  • Abasic site cleavage can generate novel interstrand cross-links that impede DNA replication.
  • These findings suggest a mechanism by which endogenous DNA damage may contribute to disease.
  • Developed LC-MS/MS methods offer valuable tools for studying these DNA cross-links.

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