N-terminal domain of metazoan Nei-like glycosylase 1 (NEIL1)This family contains the N-terminal domain of metazoan NEIL1. It belongs to the FpgNei_N, [N-terminal domain of Fpg (formamidopyrimidine-DNA glycosylase, MutM)_Nei (endonuclease VIII)] domain superfamily. DNA glycosylases maintain genome integrity by recognizing base lesions created by ionizing radiation, alkylating or oxidizing agents, and endogenous reactive oxygen species. They initiate the base-excision repair process, which is completed with the help of enzymes such as phosphodiesterases, AP endonucleases, DNA polymerases and DNA ligases. DNA glycosylases cleave the N-glycosyl bond between the sugar and the damaged base, creating an AP (apurinic/apyrimidinic) site. Most FpgNei DNA glycosylases use their N-terminal proline residue as the key catalytic nucleophile, and the reaction proceeds via a Schiff base intermediate. NEIL1 recognizes the oxidized pyrimidines 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG) and 4,6-diamino- 5-formamidopyrimidine (FapyA), thymine glycol (Tg) and 5-hydroxyuracil (5-OHU). However, even though it has weak activity on 8-oxo-7,8-dihydroguanine (8-oxoG), it does show strong preference for the products of its further oxidation: spiroiminodihydantoin and guanidinohydantoin. In addition to this MeNeil1_N domain, enzymes belonging to this family contain a helix-two turn-helix (H2TH) domain and a zincless finger motif. This characteristic "zincless finger" motif, is a structural equivalent of the zinc finger common to other members of the Fpg/Nei family. Neil1 is one of three homologs found in eukaryotes and its lineage extends back as far as early metazoans.