Excision of products of oxidative DNA base damage by human NTH1 protein.
A functional human homologue of Escherichia coli endonuclease III (Nth-Eco protein) has recently been cloned and characterized [Aspinwall, R., Rothwell, D. G., Roldan-Arjona, T., Anselmino, C., Ward, C. J., Cheadle, J. P., Sampson, J. R., Lindahl, T., Harris, P. C., and Hickson, I. D. (1997) Proc. Natl. Acad. Sci. U.S.A., 94, 109-114]. This enzyme, designated hNTH1 protein, shares an extensive sequence similarity with Nth-Eco protein and a related enzyme from Schizosaccharomyces pombe (Nth-Spo protein). We investigated the substrate specificity of this human enzyme for oxidative DNA base damage, using the technique of gas chromatography/isotope-dilution mass spectrometry. Four different DNA substrates damaged by various free radical-generating systems were used. 5-Hydroxycytosine, thymine glycol, 5-hydroxy-6-hydrothymine, 5,6-dihydroxycytosine, and 5-hydroxyuracil were substrates of hNTH1 protein among 17 lesions found in DNA substrates. The substrate specificity and excision kinetics of the human enzyme were found to be significantly different from those of Nth-Spo and Nth-Eco proteins.
Dizdaroglu
M
M
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Karahalil
B
B
Sentürker
S
S
Buckley
T J
TJ
Roldán-Arjona
T
T
D001463:Barbiturates / Q000378:metabolism; D003596:Cytosine / Q000031:analogs & derivatives / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D004260:DNA Repair; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D006801:Humans; D007700:Kinetics; D010084:Oxidation-Reduction; D013379:Substrate Specificity; D013941:Thymine / Q000031:analogs & derivatives / Q000378:metabolism; D014498:Uracil / Q000031:analogs & derivatives / Q000378:metabolism
D001463:Barbiturates; D029968:Escherichia coli Proteins; C029389:thymine glycol; C032211:isouramil; C045975:5-hydroxyuracil; D014498:Uracil; C017400:5-hydroxycytosine; D003596:Cytosine; D004247:DNA; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; C468347:NTHL1 protein, human; D013941:Thymine