Shimizu Masatomi, Gruz Petr, Kamiya Hiroyuki, Masutani Chikahide, Xu Yan, Usui Yukio, Sugiyama Hiroshi, Harashima Hideyoshi, Hanaoka Fumio, Nohmi Takehiko
Division of Genetics and Mutagenesis, National Institute of Health Sciences, Tokyo, Japan.
Biochemistry. 2007 May 8;46(18):5515-22. doi: 10.1021/bi062238r. Epub 2007 Apr 18.
Altered oxidative metabolism is a property of many tumor cells. Oxidation of DNA precursors, i.e., dNTP pool, as well as DNA is a major source of mutagenesis and carcinogenesis. Here, we report the remarkable nature of human DNA polymerase eta that incorporates oxidized dNTPs into a nascent DNA strand in an efficient and erroneous manner. The polymerase almost exclusively incorporated 8-hydroxy-dGTP (8-OH-dGTP) opposite template adenine (A) at 60% efficiency of normal dTTP incorporation, and incorporated 2-hydroxy-dATP (2-OH-dATP) opposite template thymine (T), guanine (G), or cytosine (C) at substantial rates. The synthetic primers having 8-hydroxy-G paired with template A or 2-hydroxy-A paired with template T, G, or C at the termini were efficiently extended. In contrast, human DNA polymerase iota incorporated 8-OH-dGTP opposite template A with much lower efficiency and did not incorporate 2-OH-dATP opposite any of the template bases. It did not extend the primers having the oxidized bases at the termini either. We propose that human DNA polymerase eta may participate in oxidative mutagenesis through the efficient and erroneous incorporation of oxidized dNTPs during DNA synthesis.
氧化代谢改变是许多肿瘤细胞的一个特性。DNA前体（即dNTP库）以及DNA的氧化是诱变和致癌的主要来源。在此，我们报道了人类DNA聚合酶η的显著特性，它能以高效且错误的方式将氧化的dNTP掺入新生DNA链中。该聚合酶几乎只在正常dTTP掺入效率的60%时，将8-羟基-dGTP（8-OH-dGTP）掺入与模板腺嘌呤（A）相对的位置，并以相当高的速率将2-羟基-dATP（2-OH-dATP）掺入与模板胸腺嘧啶（T）、鸟嘌呤（G）或胞嘧啶（C）相对的位置。在末端具有与模板A配对的8-羟基-G或与模板T、G或C配对的2-羟基-A的合成引物能够被有效延伸。相比之下，人类DNA聚合酶ι将8-OH-dGTP掺入与模板A相对位置的效率要低得多，并且不会将2-OH-dATP掺入任何模板碱基相对的位置。它也不会延伸在末端具有氧化碱基的引物。我们提出，人类DNA聚合酶η可能通过在DNA合成过程中高效且错误地掺入氧化的dNTP而参与氧化诱变。
