Neisseria meningitides Nape-like subfamily of the ExoIII family purinic/apyrimidinic (AP) endonucleases
This subfamily includes Neisseria meningitides Nape and related proteins. These are Escherichia coli exonuclease III (ExoIII)-like AP endonucleases and belong to the large EEP (exonuclease/endonuclease/phosphatase) superfamily that contains functionally diverse enzymes that share a common catalytic mechanism of cleaving phosphodiester bonds. AP endonucleases participate in the DNA base excision repair (BER) pathway. AP sites are one of the most common lesions in cellular DNA. During BER the damaged DNA is first recognized by DNA glycosylase. AP endonucleases then catalyze the hydrolytic cleavage of the phosphodiester bond 5' to the AP site, and this is followed by the coordinated actions of DNA polymerase, deoxyribose phosphatase, and DNA ligase. If left unrepaired, AP sites block DNA replication, and have both mutagenic and cytotoxic effects. AP endonucleases can carry out a variety of excision and incision reactions on DNA, including 3'-5' exonuclease, 3'-deoxyribose phosphodiesterase, 3'-phosphatase, and occasionally, nonspecific DNase activities. Different AP endonuclease enzymes catalyze the different reactions with different efficiences. Many organisms have two AP endonucleases, usually one is the dominant AP endonuclease, the other has weak AP endonuclease activity; for example, Neisseria meningitides Nape and NExo. Nape, found in this subfamily, is the dominant AP endonuclease. It exhibits strong AP endonuclease activity, and also exhibits 3'-5'exonuclease and 3'-deoxyribose phosphodiesterase activities.
Comment:based on similarity to ExoIII-like AP endonuclease and other EEP superfamily members; compared with other EEP superfamily members, members of this family have a conserved Tyr residue is in place of a conserved His
Jiyao W et al.(2023). "The conserved domain database in 2023.",