E.Coli中alkA基因启动子点突变对MNNG作用的表达

Point Mutation of alkA Gene promoter Induced by MNNG in Escherichia Coli

目的:研究alkA基因启动子点突变受N—methyl—N＇—nitro—N—nitrosoguanidine(MNNG)诱导,获得高β-半乳糖苷酶活性表达的突变克隆株,用于抗肿瘤的基因治疗。方法:采用人工突变方法制成alkA基因启动子区点突变,经MNNG诱导后测定点突变株β-半乳糖苷酶活性。结果:共获得点突变株46个,其中插入突变1个,置换突变26个,缺失突变8个,双突变11个。在突变株中,3株受MNNG诱导β—半乳糖苷酶活性表达高于野生型。结论:alkA基因启动子点突变克隆株受MNNG诱导β-半乳糖苷酶活性表达不同,93.5％低于野生型,有6.5％突变株高于野生型。

Objective: We studied the expression of point mutational alkA gene promoter induced by MNNG in Escherichia coli to obtain the point mutational clones which have higher β-galactosidase activity in anticarcinoma gene therapy. Methods: We obtained the point mutation at promoter region by the method of artificial mutation, and determined β-galactosidase activity induced by MNNG. Results: Forty-six of mutational clones, including 1 of insertion, 26 of substitute, 8 of deletive, and 11 of double mutation, were obtained. In 3 clones in the substitutive mutation were obtained, the enzyme activity induced by MNNG were higher than that of the wild type. Conclusion: The enzyme activity was different from the wild type when mutational alkA gene promoter was induced by MNNG. About 93. 5% was lower than the wild type, and 6.5% was higher than the wild type.