Accepted name: deoxyribonuclease IV
Reaction: Endonucleolytic cleavage of ssDNA at apurinic/apyrimidinic sites to 5′-phosphooligonucleotide end-products
Other name(s): deoxyribonuclease IV (phage-T4-induced) (misleading); endodeoxyribonuclease IV (phage T4-induced) (misleading); E. coli endonuclease IV; endodeoxyribonuclease (misleading); redoxyendonuclease; deoxriboendonuclease (misleading); endonuclease II; endonuclease IV; DNA-adenine-transferase; nfo (gene name)
Comments: The enzyme is an apurinic/apyrimidinic (AP) site endonuclease that primes DNA repair synthesis at AP sites. It specifically cleaves the DNA backbone at AP sites and also removes 3′ DNA-blocking groups such as 3′ phosphates, 3′ phosphoglycolates, and 3′ α,β-unsaturated aldehydes that arise from oxidative base damage and the activity of combined glycosylase/lyase enzymes. It is also the only known repair enzyme that is able to cleave the DNA backbone 5′ of the oxidative lesion α-deoxyadenosine. The enzyme has a strong preference for single-stranded DNA.
1.  Friedberg, E.C. and Goldthwait, D.A. Endonuclease II of E. coli. I. Isolation and purification. Proc. Natl. Acad. Sci. USA 62 (1969) 934–940. [PMID: 4895219]
2.  Friedberg, E.C., Hadi, S.-M. and Goldthwait, D.A. Endonuclease II of Escherichia coli. II. Enzyme properties and studies on the degradation of alkylated and native deoxyribonucleic acid. J. Biol. Chem. 244 (1969) 5879–5889. [PMID: 4981786]
3.  Hadi, S.M. and Goldthwait, D.A. Endonuclease II of Escherichia coli. Degradation of partially depurinated deoxyribonucleic acid. Biochemistry 10 (1971) 4986–4993. [PMID: 4944066]
4.  Cunningham, R.P., Saporito, S.M., Spitzer, S.G. and Weiss, B. Endonuclease IV (nfo) mutant of Escherichia coli. J. Bacteriol. 168 (1986) 1120–1127. [PMID: 2430946]
5.  Ide, H., Tedzuka, K., Shimzu, H., Kimura, Y., Purmal, A.A., Wallace, S.S. and Kow, Y.W. Alpha-deoxyadenosine, a major anoxic radiolysis product of adenine in DNA, is a substrate for Escherichia coli endonuclease IV. Biochemistry 33 (1994) 7842–7847. [PMID: 7516707]
6.  Hosfield, D.J., Guan, Y., Haas, B.J., Cunningham, R.P. and Tainer, J.A. Structure of the DNA repair enzyme endonuclease IV and its DNA complex: double-nucleotide flipping at abasic sites and three-metal-ion catalysis. Cell 98 (1999) 397–408. [PMID: 10458614]
[EC created 1972 as EC, transferred 1978 to EC, modified 2014]

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