Base-pairing preferences, physicochemical properties and mutational behaviour of the DNA lesion 8-nitroguanine

Nucleic Acids Res. 2012 Nov;40(21):11126-38. doi: 10.1093/nar/gks799. Epub 2012 Sep 10.

Abstract

8-Nitro-2'-deoxyguanosine (8-nitrodG) is a relatively unstable, mutagenic lesion of DNA that is increasingly believed to be associated with tissue inflammation. Due to the lability of the glycosidic bond, 8-nitrodG cannot be incorporated into oligodeoxynucleotides (ODNs) by chemical DNA synthesis and thus very little is known about its physicochemical properties and base-pairing preferences. Here we describe the synthesis of 8-nitro-2'-O-methylguanosine, a ribonucleoside analogue of this lesion, which is sufficiently stable to be incorporated into ODNs. Physicochemical studies demonstrated that 8-nitro-2'-O-methylguanosine adopts a syn conformation about the glycosidic bond; thermal melting studies and molecular modelling suggest a relatively stable syn-8-nitroG·anti-G base pair. Interestingly, when this lesion analogue was placed in a primer-template system, extension of the primer by either avian myeloblastosis virus reverse transcriptase (AMV-RT) or human DNA polymerase β (pol β), was significantly impaired, but where incorporation opposite 8-nitroguanine did occur, pol β showed a 2:1 preference to insert dA over dC, while AMV-RT incorporated predominantly dC. The fact that no 8-nitroG·G base pairing is seen in the primer extension products suggests that the polymerases may discriminate against this pairing system on the basis of its poor geometric match to a Watson-Crick pair.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Pairing
  • DNA / biosynthesis
  • DNA Damage*
  • Guanine / analogs & derivatives*
  • Guanine / chemistry
  • Guanosine / analogs & derivatives*
  • Guanosine / chemical synthesis
  • Guanosine / chemistry
  • Hydrolysis
  • Mutagenesis*
  • Mutation
  • Oligodeoxyribonucleotides / chemical synthesis
  • Oligodeoxyribonucleotides / chemistry
  • Templates, Genetic

Substances

  • 8-nitro-2'-O-methylguanosine
  • 8-nitroguanine
  • Oligodeoxyribonucleotides
  • Guanosine
  • Guanine
  • DNA