Identification and characterization of a novel human DNA glycosylase for repair of cytosine-derived lesions.
Two candidate human orthologs of Escherichia coli MutM/Nei were recently identified in the human genome database, and one of these, NEH1, was characterized earlier (Hazra, T. K., Izumi, T., Boldogh, I., Imhoff, B., Kow, Y. W., Jaruga, P., and Dizdaroglu, M. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 3523-3528). Here we report characterization of the second protein, originally named NEH2 and now renamed NEIL2 (Nei-like). The 37-kDa wild-type NEIL2 expressed in and purified from E. coli has DNA glycosylase/AP lyase activity, primarily for excising oxidative products of cytosine, with highest activity for 5-hydroxyuracil, one of the most abundant and mutagenic lesions induced by reactive oxygen species, and with lower activity for 5,6-dihydrouracil and 5-hydroxycytosine. It has negligible or undetectable activity with 8-oxoguanine, thymine glycol, 2-hydroxyadenine, hypoxanthine, and xanthine. NEIL2 is similar to NEIL1 in having N-terminal Pro as the active site. However, unlike NEIL1, its expression was independent of the cell cycle stage in fibroblasts, and its highest expression was observed in the testes and skeletal muscle. Despite the absence of a putative nuclear localization signal, NEIL2 was predominantly localized in the nucleus. These results suggest that NEIL2 is involved in global genome repair mainly for removing oxidative products of cytosine.
Hazra
Tapas K
TK
Department of Human Biological Chemistry and Genetics, Sealy Center for Molecular Science, University of Texas Medical Branch, 6.136 Medical Research Building, Rte 1079, Galveston, TX 77555, USA. tkhazra@utmb.edu
Kow
Yoke W
YW
Hatahet
Zafar
Z
Imhoff
Barry
B
Boldogh
Istvan
I
Mokkapati
Sanath K
SK
Mitra
Sankar
S
Izumi
Tadahide
T
D002453:Cell Cycle; D002467:Cell Nucleus / Q000201:enzymology; D003596:Cytosine / Q000378:metabolism*; D045647:DNA Glycosylases; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D006801:Humans; D009699:N-Glycosyl Hydrolases / Q000032:analysis / Q000302:isolation & purification / Q000502:physiology*; D009928:Organ Specificity; D011994:Recombinant Proteins / Q000302:isolation & purification; D014498:Uracil / Q000031:analogs & derivatives* / Q000378:metabolism
D011994:Recombinant Proteins; C045975:5-hydroxyuracil; D014498:Uracil; D003596:Cytosine; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C473634:NEIL1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; C473642:NEIL2 protein, human