Kumura K, Sekiguchi M
J Biol Chem. 1984 Feb 10;259(3):1560-5.
Taking advantage of overproduction of the uvrD protein in cells that harbor multicopy plasmids carrying the uvrD gene, we have purified protein to physical homogeneity. The purified protein possesses single-stranded DNA-dependent ATPase and ATP-dependent DNA unwinding activities, and both activities are equally inactivated by antibodies raised against DNA helicase II. Molecular weight (75,000) and chromatographic properties of the uvrD protein are also similar to those of DNA helicase II and DNA-dependent ATPase I (Richet, E., and Kohiyama, M. (1976) J. Biol. Chem. 251, 808-812; Abdel-Monem, M., Dürwald, H., and Hoffmann-Berling, H. (1977) Eur. J. Biochem. 79, 39-45). Thus, it is concluded that the uvrD protein is identical with DNA helicase II and DNA-dependent ATPase I. Expression of the uvrD gene, as assayed by DNA-dependent ATPase activity, was stimulated by exposure of bacteria to nalidixic acid or mitomycin C. No increase in ATPase activity was observed with recA mutant cells, although basic levels of DNA-dependent ATPase activity in recA+ and recA- strains were almost the same. Thus, the uvrD gene is constitutively expressed but also regulated in a recA-dependent fashion.
利用携带uvrD基因的多拷贝质粒在细胞中过量产生uvrD蛋白，我们已将该蛋白纯化至物理纯。纯化后的蛋白具有单链DNA依赖性ATP酶和ATP依赖性DNA解旋活性，并且这两种活性均被抗DNA解旋酶II的抗体同等程度地灭活。uvrD蛋白的分子量（75,000）和色谱性质也与DNA解旋酶II和DNA依赖性ATP酶I相似（里歇特，E.，和小山市，M.（1976年）《生物化学杂志》251，808 - 812；阿卜杜勒 - 莫奈姆，M.，迪尔瓦尔德，H.，和霍夫曼 - 贝林，H.（1977年）《欧洲生物化学杂志》79，39 - 45）。因此，可以得出结论，uvrD蛋白与DNA解旋酶II和DNA依赖性ATP酶I相同。通过DNA依赖性ATP酶活性测定，uvrD基因的表达受到细菌暴露于萘啶酸或丝裂霉素C的刺激。recA突变细胞未观察到ATP酶活性增加，尽管recA +和recA -菌株中DNA依赖性ATP酶活性的基础水平几乎相同。因此，uvrD基因是组成型表达的，但也以recA依赖性方式受到调控。
