N-terminal domain of the plant and fungal Nei and related proteins
This family contains the N-terminal domain of plant and Fungi Nei and related proteins. 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. The plant and fungal FpgNei glycosylases prefer the oxidized pyrimidines spiroiminodihydantoin (Sp), guanidinohydantoin (Gh) over 8-oxoguanine in double stranded oligonucleotides and also show weak activity on single stranded DNA. In addition to this domain, enzymes belonging to this family contain a helix-two turn-helix (H2TH) domain and a characteristic zincless finger motif. They share a common ancestor not shared with other eukaryotic members of the FpgNei family.