Endonuclease V (ENDOV)

Deamination of DNA bases can occur spontaneously, generating highly mutagenic lesions such as uracil and hypoxanthine. The alkylbase DNA glycosylase, AlkA, initiates repair by removal of the damaged base, whereas endonuclease V, Endo V, hydrolyses the second phosphodiester bond 3' to the lesion.The 37-kDa mouse enzyme (mEndo V) incises the DNA strand at the second phosphodiester bond 3' to hypoxanthine- and uracil-containing nucleotides. The activity of mEndo V is elevated on single-stranded DNA substrate in vitro. mEndo V initiates an alternative excision repair pathway for hypoxanthine removal. It thus appears that mEndo V has properties overlapping the function of alkylbase DNA glycosylase (Aag) in repair of deaminated adenine, which to some extent could explain the absence of phenotypic abnormalities associated with Aag knockout in mice.