Murphy Terence M, George Adia
Plant Biology Section, University of California, Davis, CA 95616, USA.
Biochem Biophys Res Commun. 2005 Apr 15;329(3):869-72. doi: 10.1016/j.bbrc.2005.02.054.
Plants contain the genes for both formamidopyrimidine-DNA glycosylase (FPG) and oxoguanine glycosylase (OGG). These enzymes play analogous roles in the base excision repair pathways of bacteria (FPG) and archaea, yeast, and mammals (OGG). Why have plants retained both genes? We tested one hypothesis by comparing the specificities of Arabidopsis FPG and OGG purified from Escherichia coli expression clones. Using depurinated DNA as substrate, the specific activity of Arabidopsis FPG was higher than that of Arabidopsis OGG. Using DNA oxidized by treatment with light in the presence of methylene blue, the specific activities of Arabidopsis FPG and OGG were equal. Using an oligonucleotide containing one oxoguanine (paired with C) and labeled with fluorescein, the specific activity of Arabidopsis OGG was greater than that of either FPG. The results support the hypothesis that genes for the two enzymes have been retained during evolution of plants for their specialized enzyme activities.
植物含有甲酰胺嘧啶 - DNA糖基化酶（FPG）和氧代鸟嘌呤糖基化酶（OGG）的基因。这些酶在细菌（FPG）、古细菌、酵母和哺乳动物（OGG）的碱基切除修复途径中发挥类似作用。为什么植物保留了这两种基因呢？我们通过比较从大肠杆菌表达克隆中纯化的拟南芥FPG和OGG的特异性来检验一种假设。以脱嘌呤DNA为底物时，拟南芥FPG的比活性高于拟南芥OGG。以在亚甲蓝存在下经光照处理氧化的DNA为底物时，拟南芥FPG和OGG的比活性相等。以含有一个氧代鸟嘌呤（与C配对）并标记有荧光素的寡核苷酸为底物时，拟南芥OGG的比活性大于FPG中的任何一种。结果支持了这样一种假设，即在植物进化过程中，这两种酶的基因因其特殊的酶活性而得以保留。
