8-oxoguanine or oxoG is a major oxidation product generated in cells. The modification is removed from the nucleotide pool by the enzymatic hydrolysis of 8-oxo-2′-deoxyguanosine triphosphate and from genomic DNA by 8-oxoguanine-DNA glycosylase. Oxidation of DNA caused by reactive oxygen species (ROS) generated during aerobic respiration is a major cause of genetic damage. It has been reported in the scientific literature that this damage, if not repaired, can lead to mutations and potentially an increase in the incidence of cancer and aging.
Cells have protein based repair mechanisms that find and repair oxoG within a large excess of unmodified DNA. The process requires a combination of rapid scanning of the DNA for the lesion followed by specific excision of the damaged base. The repair of oxoG involves flipping the lesion out of the DNA stack and into the active site of the 8-oxoguanine-DNA glycosylase, as was revealed by biochemical studies.
Reference
Sreelekha K. Singh, Marta W. Szulik, Manjori Ganguly, Irine Khutsishvili, Michael P. Stone, Luis A. Marky, and Barry Gold; Characterization of DNA with an 8-oxoguanine modification. Nucleic Acids Res. Aug 2011; 39(15): 6789–6801.