Identification and characterization of a novel human DNA glycosylase for repair of cytosine-derived lesions
Identification and characterization of a novel human DNA glycosylase for repair of cytosine-derived lesions
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DOI：
10.1074/jbc.c200355200
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发表时间：
2002-08-23
影响因子：
4.8
通讯作者：
Izumi, T
中科院分区：
文献类型：
--
作者：
Hazra, TK;Kow, YW;Izumi, T
最近在人类基因组数据库中鉴定了大肠杆菌MutM/Nei的两种候选人类直向同源物，并且其中之一NEH 1较早被表征（Hazra，T. K.，Izumi，T.，博尔多岛Imhoff，B.，Kow，Y. W.，Jaruga，P.，和Dizdaroglu，M.等人（2002）Proc. Acad. Sci.联合S. A. 99，3523-3528）。在这里，我们报告的第二种蛋白质，最初命名为NEH 2，现在更名为NEIL 2（Nei样）的表征。在大肠杆菌中表达并纯化了37-kDa的野生型NEIL 2。大肠杆菌具有DNA糖基化酶/AP裂解酶活性，主要用于切除胞嘧啶的氧化产物，对5-羟基尿嘧啶具有最高的活性，5-羟基尿嘧啶是活性氧物质诱导的最丰富和致突变的损伤之一，而对5，6-二氢尿嘧啶和5-羟基胞嘧啶具有较低的活性。对8-氧代鸟嘌呤、胸腺嘧啶乙二醇、2-羟基腺嘌呤、次黄嘌呤和黄嘌呤的活性可忽略不计或检测不到。NEIL 2与NEIL 1相似，具有N-末端Pro作为活性位点。然而，与NEIL 1不同的是，其表达与成纤维细胞的细胞周期阶段无关，并且在睾丸和骨骼肌中观察到其最高表达。尽管没有推定的核定位信号，NEIL 2主要定位在细胞核中。这些结果表明，NEIL 2参与了全球基因组修复，主要是为了消除胞嘧啶的氧化产物。
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.