Cai J P, Kakuma T, Tsuzuki T, Sekiguchi M
Department of Biochemistry, Kyushu University 69, Fukuoka, Japan.
Carcinogenesis. 1995 Oct;16(10):2343-50. doi: 10.1093/carcin/16.10.2343.
The enzyme, 8-oxo-7,8-dihydrodeoxyguanosine triphosphatase (8-oxo-dGTPase), is present in various organisms and plays an important role in control of spontaneous mutagenesis. This enzyme degrades 8-oxoguanine-containing deoxyribonucleoside triphosphate, a potentially mutagenic substrate for DNA synthesis, to the corresponding monophosphate. To obtain appropriate probes for expression of the gene in various tissues and also to construct appropriate experimental models for carcinogenesis, we cloned cDNA for rat 8-oxo-dGTPase and elucidated its structure. The nucleotide sequence of the cDNA revealed that the rat 8-oxo-dGTPase protein is composed of 156 amino acid residues. The molecular weight of rat 8-oxo-dGTPase, calculated from the predicted amino acid sequence, was 18,006, and the 8-oxo-dGTPase protein of this size was detected when the cDNA was expressed in 8-oxo-dGTPase-deficient Escherichia coli mutT- cells. The predicted amino acid sequence of the rat 8-oxo-dGTPase has a close homology with those of human and bacterial counterparts. Using the cDNA as a probe, part of the rat gene for 8-oxo-dGTPase was isolated and was found to consist of at least three exons and spanned about 10 kb. A genomic region containing the pseudogene was also isolated.
8-氧代-7,8-二氢脱氧鸟苷三磷酸酶（8-氧代-dGTPase）这种酶存在于多种生物体中，在控制自发突变方面发挥着重要作用。该酶将含8-氧代鸟嘌呤的脱氧核糖核苷三磷酸（一种DNA合成的潜在诱变底物）降解为相应的单磷酸。为了获得用于该基因在各种组织中表达的合适探针，并构建合适的致癌实验模型，我们克隆了大鼠8-氧代-dGTPase的cDNA并阐明了其结构。cDNA的核苷酸序列显示，大鼠8-氧代-dGTPase蛋白由156个氨基酸残基组成。根据预测的氨基酸序列计算，大鼠8-氧代-dGTPase的分子量为18,006，当该cDNA在缺乏8-氧代-dGTPase的大肠杆菌mutT-细胞中表达时，检测到了这种大小的8-氧代-dGTPase蛋白。大鼠8-氧代-dGTPase的预测氨基酸序列与人类和细菌的对应序列具有密切的同源性。以该cDNA为探针，分离出了大鼠8-氧代-dGTPase基因的一部分，发现它至少由三个外显子组成，跨度约为10 kb。还分离出了一个包含假基因的基因组区域。
