DNA-(Apurinic or Apyrimidinic Site) Lyase

Human N-Glycosylase DNA Lyase(OOG1) is a DNA repair enzyme, which belongs to the type-1 OGG1 family. OOG1 incises DNA at 8-oxoG residues, and excises 7,8-dihydro-8-oxoguanine and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine (FAPY) from damage DNA. It has a β-lyase activity that nicks DNA 3' to the lesion. OOG1 together with APEX1 is recruited to nuclear speckles in UVA-irradiated cells. The OGG1 gene mutations may be caused Renal cell carcinoma.

Apurinic-Apyrimidinic Endonuclease 1 (APE1) is required for efficient DNA base excision repair. When the DNA glycosylase remove the damaged bases, APE1 cleaves the AP site to allow resynthesis and ligation to complete repair. APE1 stimulates the DNA binding activity of many transcription factors, which participate in cancer promotion and progression. APE1 regulates the redox state of multiple transcription factors, such as c-Jun, c-Fos, NF-kB, p53. APEN is also involved in calcium-dependent down-regulation of PTH expression.

NEIL1 is a member of DNA glycosylases. DNA glycosylases are a family homologous to the bacterial Fpg Nei family. They play a role in base excision repair which is the mechanism by which damaged bases in DNA are removed and replaced. The first step of this process is catalyzed by DNA glycosylases. They remove the damaged nitrogenous base while leaving the sugar-phosphate backbone intact, creating an apurinic apyrimidinic site, commonly referred to as an AP site. NEIL1 functions in base excision repair of DNA damaged by oxidation or by mutagenic agents. It acts as a DNA glycosylase that recognizes and removes damaged bases. NEIL1 prefers to oxidized pyrimidines, such as thymine glycol, Formamidopyrimidine (Fapy), and 5-hydroxyuracil. Has marginal activity towards 8-oxoguanine. It has AP (apurinic apyrimidinic) lyase activity and introduces nicks in the DNA strand and cleaves the DNA backbone by beta-delta elimination to generate a single-strand break at the site of the removed base with both 3'- and 5'-phosphates.