Enzymatic repair of an expanded genetic information system

Nucleic Acids Res. 2003 Sep 1;31(17):5048-53. doi: 10.1093/nar/gkg709.


The excision repair machinery of a thermophilic bacterium has been shown to recognize and repair an expanded genetic base pair. Native Thermus aquaticus DNA polymerase will remove a mispaired natural base and replace it with a non-natural base to form an expanded base pair. In addition, DNA ligase will recognize a nick formed by polymerase between two non-natural base pairs and covalently attach the two strands, thus demonstrating complete repair of a bifurcated base-paired model duplex. These results add evidence to the idea that the cellular replication and repair machinery of an organism containing an expanded genetic alphabet could recognize and properly repair a site containing consecutive unnatural bases.

MeSH terms

  • Base Pair Mismatch / genetics
  • DNA / genetics
  • DNA / metabolism
  • DNA Ligases / metabolism
  • DNA Repair*
  • DNA-Directed DNA Polymerase / metabolism
  • Deoxyribonucleases / metabolism
  • Enzymes / metabolism*
  • Models, Genetic


  • Enzymes
  • DNA
  • DNA-Directed DNA Polymerase
  • Deoxyribonucleases
  • DNA Ligases