Characterization of a novel 8-oxoguanine-DNA glycosylase activity in Escherichia coli and identification of the enzyme as endonuclease VIII.
Characterization of a novel 8-oxoguanine-DNA glycosylase activity in Escherichia coli and identification of the enzyme as endonuclease VIII.
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DOI：
10.1074/jbc.m004052200
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发表时间：
2000-09
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影响因子：
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通讯作者：
T. Hazra;T. Izumi;Radhika Venkataraman;Y. Kow;M. Dizdaroglu;S. Mitra
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文献类型：
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作者：
T. Hazra;T. Izumi;Radhika Venkataraman;Y. Kow;M. Dizdaroglu;S. Mitra
8-氧代鸟嘌呤（G*）是活性氧诱导的，由于它与A错配而具有致突变性。主要的G*-DNA糖基化酶（OGG），即真核生物中的OGG 1或大肠杆菌中的MutM，当在DNA中与C、G和T配对时切除G*，但不切除A，可能是因为从G* 中去除G*。然而，G* 的修复将防止突变，当它被纳入新生链对面的A。这可以通过在酵母和人类细胞中鉴定的第二个OGG OGG 2来进行。我们在E.大肠杆菌中，然后确定它是核酸内切酶VIII（Nei），发现作为一个受损的嘧啶特异性DNA糖基化酶。Nei与MutM具有序列同源性和反应机制，并且在与A（或G）配对时能够切除G* 方面与人OGG 2相似。野生型Nei的动力学分析表明，相对于二氢尿嘧啶，它具有显著的切除G* 的活性。OGG 2型酶在大肠杆菌和大肠杆菌中均存在。大肠杆菌和真核生物中，从G*.A（或G）对中切除G* 至少与从G*.C对中切除G* 一样有效，这支持了新生DNA链中G* 修复的可能性。
8-Oxoguanine (G*), induced by reactive oxygen species, is mutagenic because it mispairs with A. The major G*-DNA glycosylase (OGG), namely, OGG1 in eukaryotes, or MutM in Escherichia coli, excises G* when paired in DNA with C, G, and T, but not A, presumably because removal of G* from a G*.A pair would be mutagenic. However, repair of G* will prevent mutation when it is incorporated in the nascent strand opposite A. This could be carried out by a second OGG, OGG2, identified in yeast and human cells. We have characterized a new OGG activity in E. coli and then identified it to be endonuclease VIII (Nei), discovered as a damaged pyrimidine-specific DNA glycosylase. Nei shares sequence homology and reaction mechanism with MutM and is similar to human OGG2 in being able to excise G* when paired with A (or G). Kinetic analysis of wild type Nei showed that it has significant activity for excising G* relative to dihydrouracil. The presence of OGG2 type enzyme in both E. coli and eukaryotes, which is at least as efficient in excising G* from a G*.A (or G) pair as from a G*.C pair, supports the possibility of G* repair in the nascent DNA strand.