Cyclobutane pyrimidine dimers and (6-4) photoproducts block polymerization by DNA polymerase I

Biochemistry. 1985 Oct 8;24(21):5723-8. doi: 10.1021/bi00342a006.


Bipyrimidine cyclobutane dimers and 6-4'-(pyrimidin-2'-one)-pyrimidine photoproducts are the major adducts formed in DNA following exposure to ultraviolet light. The relationship between the type and frequency of UV-induced DNA damage and the effects of such damage on DNA replication were investigated. UV-irradiated M13 phage DNA was employed in polymerization reactions with the Kenow fragment of Escherichia coli DNA polymerase I. The locations and frequencies of polymerase termination events occurring within a defined sequence of M13 DNA were compared with measurements of the locations and frequencies of UV-induced DNA damage of the same DNA sequence by using UV-specific enzymatic and chemical methods. The results indicate that both cyclobutane dimers and (6-4) photoproducts quantitatively block polymerization by DNA polymerase I.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Coliphages / genetics
  • DNA Polymerase I / antagonists & inhibitors*
  • DNA Replication / radiation effects
  • DNA, Viral / radiation effects*
  • Dose-Response Relationship, Radiation
  • Genes, Viral
  • Kinetics
  • Pyrimidine Dimers*
  • Pyrimidinones*
  • T-Phages / enzymology
  • Templates, Genetic
  • Ultraviolet Rays*


  • DNA, Viral
  • Pyrimidine Dimers
  • Pyrimidinones
  • DNA Polymerase I