Human endonuclease V as a repair enzyme for DNA deamination.
The human endonuclease V gene is located in chromosome 17q25.3 and encodes a 282 amino acid protein that shares about 30% sequence identity with bacterial endonuclease V. This study reports biochemical properties of human endonuclease V with respect to repair of deaminated base lesions. Using soluble proteins fused to thioredoxin at the N-terminus, we determined repair activities of human endonuclease V on deoxyinosine (I)-, deoxyxanthosine (X)-, deoxyoxanosine (O)- and deoxyuridine (U)-containing DNA. Human endonuclease V is most active with deoxyinosine-containing DNA but with minor activity on deoxyxanthosine-containing DNA. Endonuclease activities on deoxyuridine and deoxyoxanosine were not detected. The endonuclease activity on deoxyinosine-containing DNA follows the order of single-stranded I>G/I>T/I>A/I>C/I. The preference of the catalytic activity correlates with the binding affinity of these deoxyinosine-containing DNAs. Mg(2+) and to a much less extent, Mn(2+), Ni(2+), Co(2+) can support the endonuclease activity. Introduction of human endonuclease V into Escherichia coli cells deficient in nfi, mug and ung genes caused three-fold reduction in mutation frequency. This is the first report of deaminated base repair activity for human endonuclease V. The relationship between the endonuclease activity and deaminated deoxyadenosine (deoxyinosine) repair is discussed.
Department of Genetics and Biochemistry, South Carolina Experiment Station, Clemson University, Room 219 Biosystems Research Complex, 105 Collings Street, Clemson, SC 29634, United States.
Rongjuan
R
Mi
Maria
M
Alford-Zappala
Yoke W
YW
Kow
Richard P
RP
Cunningham
Weiguo
W
Cao
D004247:DNA / Q000378:metabolism; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000378:metabolism*; D003641:Deamination; D043224:Deoxyribonuclease (Pyrimidine Dimer) / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D018014:Gene Transfer Techniques; D006801:Humans; D007288:Inosine / Q000031:analogs & derivatives / Q000378:metabolism; D009154:Mutation; D013879:Thioredoxins / Q000378:metabolism
D013879:Thioredoxins; D007288:Inosine; D004247:DNA; D043224:Deoxyribonuclease (Pyrimidine Dimer); D045643:DNA Repair Enzymes; C012271:deoxyinosine